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Home , Acrylate polymer

Synthesis and Characterization of

By

Misbah Sultan M.Sc. Chemistry (UAF) 2003-ag-254

A thesis submitted in partial fulfillment of the requirements for the degree of

DOCTOR OF PHILOSPHY IN CHEMISTRY DEPARTMENT OF CHEMISTRY & BIOCHEMISTRY FACULTY OF SCIENCES, UNIVERSITY OF AGRICULTURE, FAISALABAD, PAKISTAN.

2011

Certificate

To

The Controller of Examination,

The members of the Supervisory Committee find the thesis submitted by Miss. Misbah Sultan 2003-ag-254 satisfactory and recommend that it be processed for evaluation by the External Examiner(s) for the award of degree.

CHAIRMAN: …………………………………….

Co-SUPERVISOR: …......

MEMBER: …………………………………….

MEMBER: …………………………………….

ii

Declaration

I hereby declare that contents of the thesis, “Synthesis and Characterization of Polyurethane Acrylate Copolymers” are product of my own research and no part has been copied from any published source (except the references, standard methods or protocols etc.). I further declare that this work has not been submitted for award of any other diploma/degree. The university may take action if the information provided is found inaccurate at any stage. (In case of any default, the scholar will be proceeded against as per HEC plagiarism policy).

Misbah Sultan 2003-ag- 254

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Acknowledgements

I would like to thank my supervisors, Prof. Dr. Haq Nawaz Bhatti, Department of Chemistry and Biochemistry, University of Agriculture, Fasislabad and Prof. Dr. Muhammad Zuber, Department of Industrial Chemistry, Govt. College University of Fasislabad for providing me with the opportunity to work on such an exciting project, for their advice, encouragement, critical inputs and continuous guidance throughout this project. I am also grateful to them for providing me excellent working environment and unlimited easy access to discuss everything. I am also grateful to Prof. Dr. Ijaz Ahmad Bhatti and Prof. Dr. Munir Ahmad Sheikh, Department of Chemistry and Biochemistry, University of Agriculture, Faisalabad for their moral support and encouraging attitude. I am thankful to Prof. Dr. Mehdi Barikani for his continuous generous help, invaluable guidance and practical support in my Ph.D research work at Department of Polyurethane, Iran and Institute, Tehran. I am also highly indebted to Higher Education Commission (HEC), Government of Pakistan for granting me Indigenous fellowship throughout my doctoral study. Last, but certainly not least, I am grateful to my parents, caring husband, sisters and brothers for their advice and support throughout my life.

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List of Contents

Certificate ...... ii Declaration ...... iii Acknowledgements ...... iv List of Contents ...... v List of Figures ...... viii List of Tables ...... xii List of Abbreviations ...... xv List of Appendices ...... xix Abstract ...... 1 Chapter 1 ...... 2 1 Introduction ...... 3 Chapter 2 ...... 8 2 Review of Literature ...... 9 Chapter 3 ...... 26 3 Materials and Methods ...... 27 3.1 Chemicals ...... 27 3.1.1 ...... 27 3.1.1.1 Isocyanates ...... 27 3.1.1.2 Polyols...... 28 3.1.1.3 Acylates...... 29 3.1.2 Emulsifiers ...... 30 3.1.2.1 Neutral emulsifier ...... 30 3.1.2.2 Anionic emulsifier ...... 31 3.1.3 Non-surfactant stabilizer ...... 31 3.1.4 Initiator ...... 31 3.1.5 Solvents ...... 31 3.2 Methodology ...... 32 v

3.2.1 Synthesis of PU prepolymers: ...... 32 3.2.2 Introduction of unsaturation at the ends of PU prepolymers: ...... 33 3.2.3 Copolymerization of PU resin with butyl acrylate (BA) ...... 34 3.3 Characterization ...... 36 3.3.1 Fourier transform infra red spectroscopy (FT-IR) ...... 36 3.3.2 Differential scanning calorimetry (DSC) ...... 36 3.3.3 Thermogravimetric analysis (TGA) ...... 36 3.3.4 Dynamic light scattering (DLS) ...... 36 3.3.5 Viscosity of PUA emulsions ...... 37 3.3.6 Dry weight contents (%) ...... 37 3.3.7 Chemical and water resistance ...... 37 3.3.8 Pre-treatment of fabric substrate ...... 38 3.3.9 Textile Performance ...... 38 Chapter 4 ...... 39 4 Results and Discussion ...... 40 Part I ...... 40 4.1 Chemical characterization of PUA emulsions ...... 40 4.1.1 Chemical characterization of AL-1-PEG copolymer series ...... 40 4.1.2 Chemical characterization of AL-1-PCL copolymer series ...... 46 4.1.3 Chemical characterization of AL-2-PEG copolymer series ...... 50 4.1.4 Chemical characterization of AL-2-PCL copolymer series ...... 53 4.1.5 Chemical characterization of AR-3-PEG copolymer series ...... 56 4.1.6 Chemical characterization of AR-3-PCL copolymer series ...... 60 4.2 Physical properties of PUA copolymer emulsions ...... 63 4.2.1 Micelle size, PDI, stability and appearance of PUA emulsions of AL-1-PCL copolymer series ...... 64 4.2.2 Micelle size, PDI, stability and appearance of PUA emulsions of AL-2-PCL copolymer series ...... 65 4.2.3 Micelle size, PDI, stability and appearance of PUA emulsions of AR-3-PCL copolymer series ...... 67

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4.2.4 Micelle size, PDI, stability and appearance of PUA emulsions of AL-1-PEG copolymer series ...... 69 4.2.5 Micelle size, PDI, stability and appearance of PUA emulsions of AL-2-PEG copolymer series ...... 71 4.2.6 Micelle size, PDI, stability and appearance of PUA emulsions of AR-3-PEG copolymer series ...... 72 4.3 Viscosity and solid contents of PUA emulsions ...... 73 4.3.1 Viscosity and solid contents of PUA emulsions of AL-1-PCL copolymer series .... 74 4.3.2 Viscosity and solid contents of PUA emulsions of AL-2-PCL copolymer series .... 76 4.3.3 Viscosity and solid contents of PUA emulsions of AR-3-PCL copolymer series .... 78 4.3.4 Viscosity and solid contents of PUA emulsions of AL-1-PEG copolymer series .... 79 4.3.5 Viscosity and solid contents of PUA emulsions of AL-2-PEG copolymer series .... 81 4.3.6 Viscosity and solid contents of PUA emulsions of AR-3-PEG copolymer series .... 83 4.4 Chemical and water resistance of PUA copolymer emulsions ...... 84 4.5 Thermal analysis ...... 87 4.5.1 Thermogravimetric analysis (TGA) ...... 87 4.5.2 Differential scanning calorimetry (DSC) ...... 95 4.6 Textile performance of PUA copolymer series ...... 101 4.6.1 Tear strength ...... 101 4.6.2 Fastness properties of textile fabrics coated with PUA emulsions ...... 105 Part II ...... 110 4.7 Chemical characterization of AR-0-PMPGlu copolymer series ...... 110 4.8 Emulsion stability of the PUA emulsions of AR-0-PMPGlu copolymer series ...... 113 4.9 Textile performance of AR-0-PMPGlu copolymer series ...... 113 4.10 Chemical characterization of AL-0-PMPGlu copolymer series ...... 116 4.11 Physical characterization of AR-0-PMPGlu and AL-0-PMPGlu copolymer series .. 120 4.12 Chemical resistance of AR-0-PMPGlu and AL-0-PMPGlu copolymer series ...... 121 4.13 Textile performance of AR-0-PMPGlu and AL-0-PMPGlu copolymer series ...... 121 Summary ...... 123 5 References ...... 125 Appendices ...... 133 vii

List of Figures

Figure 3.1 Chemical structure of isophorone diisocyanate (IPDI) ...... 27 Figure 3.2 Chemical structure of Toluene diisocyanate (TDI) ...... 28

Figure 3.3 Chemical structure of Methylene bis (4-cyclohexylisocyanate) (H12MDI) ...... 28 Figure 3.4 Chemical structure of Poly (2-methyl-1,3-propylene glutarate) (PMPGlu), diol terminated ...... 28 Figure 3.5 Chemical structure of Polycaprolactone, CAPA2100 ...... 29 Figure 3.6 Chemical structure of Poly (oxyethylene) (PEG) ...... 29 Figure 3.7 Chemical structure of 2-Hydroxyethyl acrylate (2-HEA) ...... 30 Figure 3.8 Chemical structure of 2-Hydroxyethyl methacrylate (2-HEMA) ...... 30 Figure 3.9 Chemical structure of n-Butyl acrylate (BA) ...... 30 Figure 3.10 Synthesis of PU prepolymer by the reaction of OH groups of polyol with NCO groups of isocyanate ...... 32 Figure 3.11 Introduction of unsaturation at the ends of PU prepolymer by the reaction of NCO terminated PU prepolymer with OH groups of hydroxy acrylate ...... 33 Figure 3.12 Copolymerization of vinyl terminated PU prepolymer with butyl acrylate (BA) ..... 35

Figure 4.1 FT-IR spectra of AL-1-PEG copolymer series, a. H12MDI, b. PEG, c. PU prepolymer with free NCO groups, d. 2-HEMA, e. vinyl terminated PU prepolymer, f. BA, g. PUA copolymer ...... 43

Figure 4.2 FT-IR spectra of AL-1-PCL copolymer series, a. H12MDI, b. PCL, c. PU prepolymer with free NCO groups, d. 2-HEMA, e. vinyl terminated PU prepolymer, f. BA, g. PUA copolymer...... 49 Figure 4.3 FT-IR spectra of AL-2-PEG copolymer series, a. IPDI, b. PEG, c. PU prepolymer with free NCO groups, d. 2-HEMA, e. vinyl terminated PU prepolymer, f. BA, g. PUA copolymer ...... 52 Figure 4.4 FT-IR spectra of AL-2-PCL copolymer series, a. IPDI, b. PCL, c. PU prepolymer with free NCO groups, d. 2-HEMA, e. vinyl terminated PU prepolymer, f. BA, g. PUA copolymer . 55

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Figure 4.5 FT-IR spectra of AR-3-PEG copolymer series, a. TDI, b. PEG, c. PU prepolymer with free NCO groups, d. 2-HEMA, e. vinyl terminated PU prepolymer, f. BA, g. PUA copolymer . 59 Figure 4.6 FT-IR spectra of AR-3-PCL copolymer series, a. TDI, b. PCL, c. PU prepolymer with free NCO groups, d. 2-HEMA, e. vinyl terminated PU prepolymer, f. BA, g. PUA copolymer . 62 Figure 4.7 Particle size distribution of PUA emulsions of AL-1-PCL copolymer series ...... 65 Figure 4.8 Particle size distribution of PUA emulsions of AL-2-PCL copolymer series...... 67 Figure 4.9 Particle size distribution of PUA emulsions of AR-3-PCL copolymer series (The micelle size of AR-3.5-PCL was divided by 10 for graphical adjustment) ...... 68 Figure 4.10 Particle size distribution of PUA emulsions of AL-1-PEG copolymer series ...... 70 Figure 4.11 Particle size distribution of PUA emulsions of AL-2-PEG copolymer series ...... 72 Figure 4.12 Particle size distribution of PUA emulsions of AR-3-PEG copolymer series ...... 73 Figure 4.13 Variation in viscosity (cps) of PUA emulsions of AL-1-PCL copolymer series with variation in PU/BA % ...... 75 Figure 4.14 Variation in solid contents (%) of PUA emulsions of AL-1-PCL copolymer series with variation in PU/BA % ...... 76 Figure 4.15 Variation in viscosity (cps) of PUA emulsions of AL-2-PCL copolymer series with variation in PU/BA % ...... 77 Figure 4.16 Variation in solid contents (%) of PUA emulsions of AL-2-PCL copolymer series with variation in PU/BA % ...... 77 Figure 4.17 Variation in viscosity (cps) of PUA emulsions of AR-3-PCL copolymer series with variation in PU/BA % ...... 78 Figure 4.18 Variation in solid contents (%) of PUA emulsions of AR-3-PCL copolymer series with variation in PU/BA % ...... 79 Figure 4.19 Variation in viscosity (cps) of PUA emulsions of AL-1-PEG copolymer series with variation in PU/BA % ...... 80 Figure 4.20 Variation in solid contents (%) of PUA emulsions of AL-1-PEG copolymer series with variation in PU/BA % ...... 81 Figure 4.21 Variation in viscosity (cps) of PUA emulsions of AL-2-PEG copolymer series with variation in PU/BA % ...... 82 Figure 4.22 Variation in solid contents (%) of PUA emulsions of AL-2-PEG copolymer series with variation in PU/BA % ...... 82 ix

Figure 4.23 Variation in viscosity (cps) of PUA emulsions of AR-3-PEG copolymer series with variation in PU/BA % ...... 83 Figure 4.24 Variation in solid contents (%) of PUA emulsions of AR-3-PEG copolymer series with variation in PU/BA % ...... 84 Figure 4.25 TGA curve (10oC/min) of a representative PUA copolymer of AL-1-PCL copolymer series based on H12MDI, PCL, 2-HEMA and BA ...... 90 Figure 4.26 DTG curve (10oC/min) of a representative PUA copolymer of AL-1-PCL copolymer series based on H12MDI, PCL, 2-HEMA and BA ...... 90 Figure 4.27 TGA curve (10oC/min) of a representative PUA copolymer of AL-1-PEG copolymer series based on H12MDI, PEG, 2-HEMA and BA ...... 91 Figure 4.28 DTG curve (10oC/min) of a representative PUA copolymer of AL-1-PEG copolymer series based on H12MDI, PEG, 2-HEMA and BA ...... 91 Figure 4.29 TGA curve (10oC/min) of a representative PUA copolymer of AL-2-PCL copolymer series based on IPDI, PCL, 2-HEMA and BA ...... 92 Figure 4.30 DTG curve (10oC/min) of a representative PUA copolymer of AL-2-PCL copolymer series based on IPDI, PCL, 2-HEMA and BA ...... 92 Figure 4.31 TGA curve (10oC/min) of a representative PUA copolymer of AL-2-PEG copolymer series based on IPDI, PEG, 2-HEMA and BA...... 93 Figure 4.32 DTG curve (10oC/min) of a representative PUA copolymer of AL-2-PEG copolymer series based on IPDI, PEG, 2-HEMA and BA...... 93 Figure 4.33 TGA curve (10oC/min) of a representative PUA copolymer of AR-3-PCL copolymer series based on TDI, PCL, 2-HEMA and BA ...... 94 Figure 4.34 DTG curve (10oC/min) of a representative PUA copolymer of AR-3-PCL copolymer series based on TDI, PCL, 2-HEMA and BA ...... 94 Figure 4.35 TGA curve (10oC/min) of a representative PUA copolymer of AR-3-PEG copolymer series based on TDI, PEG, 2-HEMA and BA ...... 95 Figure 4.36 DTG curve (10oC/min) of a representative PUA copolymer of AR-3-PEG copolymer series based on TDI, PEG, 2-HEMA and BA ...... 95 Figure 4.37 DSC thermogram (10oC/min) of a representative PUA copolymer of AL-1-PCL copolymer series based on H12MDI, PCL, 2-HEMA and BA ...... 97

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Figure 4.38 DSC thermogram (10oC/min) of a representative PUA copolymer of AL-1-PEG copolymer series based on H12MDI, PEG, 2-HEMA and BA ...... 97 Figure 4.39 DSC thermogram (10oC/min) of a representative PUA copolymer of AL-2-PCL copolymer series based on IPDI, PCL, 2-HEMA and BA ...... 98 Figure 4.40 DSC thermogram (10oC/min) of a representative PUA copolymer of AL-2-PEG copolymer series based on IPDI, PEG, 2-HEMA and BA ...... 99 Figure 4.41 DSC thermogram (10oC/min) of a representative PUA copolymer of AR-3-PCL copolymer series based on TDI, PCL, 2-HEMA and BA ...... 100 Figure 4.42 DSC thermogram (10oC/min) of a representative PUA copolymer of AR-3-PEG copolymer series based on TDI, PEG, 2-HEMA and BA...... 100 Figure 4.43 FT-IR spectrum of AR-0-PMPGlu copolymer series, a. TDI, b. PMPGlu polyol, c. PU prepolymer with free NCO groups, d. 2-HEA, e. vinyl terminated PU prepolymer, f. BA, g. PUA copolymer ...... 112 Figure 4.44 FT-IR spectra of AR-0-PMPGlu copolymer series, a. TDI, b. PMPGlu polyol, c. 2- HEA, d. BA, e. TDI based polyurethane acrylate copolymers (PUAC-1) ...... 118 Figure 4.45 FT-IR spectra of AL-0-PMPGlu copolymer series, a. IPDI, b. PMPGlu polyol, c. 2- HEA, d. BA, e. IPDI based polyurethane acrylate copolymers (PUAC-2)...... 119

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List of Tables

Table 3.1 Basic ingredients for synthesis of PUA copolymer emulsions ...... 34 Table 3.2 Formulation for synthesis of PUA copolymer emulsions ...... 35 Table 3.3 Specifications of fabric substrate ...... 38 Table 4.1 Labeling, composition and PU/BA ratio for the different PUA emulsions in AL- 1- PEG copolymer series ...... 41 Table 4.2 Labeling, composition and PU/BA ratio for the different PUA emulsions in AL-1-PCL copolymer series ...... 46 Table 4.3 Labeling, composition and PU/BA ratio for the different PUA emulsions in AL-2-PEG series ...... 50 Table 4.4 Labeling, composition and PU/BA ratio for the different PUA emulsions in AL-2-PCL series ...... 53 Table 4.5 Labeling, composition and PU/BA ratio for the different PUA emulsions in AR-3-PEG series ...... 56 Table 4.6 Labeling, composition and PU/BA ratio for the different PUA emulsions in AR-3-PCL series ...... 60 Table 4.7 Sample code, composition, micelle size, PDI, stability and appearance of PUA emulsions of AL-1-PCL copolymer series...... 64 Table 4.8 Sample code, composition, micelle size, PDI, stability and appearance of PUA emulsions of AL-2-PCL copolymer series ...... 66 Table 4.9 Sample code, composition, micelle size, PDI, stability and appearance of PUA emulsions of AR-3-PCL copolymer series ...... 67 Table 4.10 Sample code, composition, micelle size, PDI, stability and appearance of PUA emulsions of AL-1-PEG copolymer series ...... 70 Table 4.11 Sample code, composition, micelle size, PDI, stability and appearance of PUA emulsions of AL-2-PEG copolymer series ...... 71 Table 4.12 Sample code, composition, micelle size, PDI, stability and appearance of PUA emulsions of AR-3-PEG copolymer series ...... 73

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Table 4.13 Sample code, composition, solid contents and viscosity of PUA emulsions of AL-1- PCL copolymer series...... 75 Table 4.14 Sample code, composition, solid contents and viscosity of PUA emulsions of AL-2- PCL copolymer series...... 76 Table 4.15 Sample code, composition, solid contents and viscosity of PUA emulsions of AR-3- PCL copolymer series...... 78 Table 4.16 Sample code, composition, solid contents and viscosity of PUA emulsions AL-1-PEG copolymer series...... 80 Table 4.17 Sample code, composition, solid contents and viscosity of PUA emulsions of AL-2- PEG copolymer series...... 81 Table 4.18 Sample code, composition, solid contents and viscosity of PUA emulsions of AR-3- PEG copolymer series...... 83 Table 4.19 Chemical and water resistance of PUA copolymer emulsions based on Methylene bis

(4-cyclohexylisocyanate) (H12MDI) ...... 85 Table 4.20 Chemical and water resistance of PUA copolymer emulsions based on 1-Isocyanato- 3-Isocyanatomethyl-3,5,5-Trimethylcyclohexane (IPDI) ...... 86 Table 4.21 Chemical and water resistance of PUA copolymer emulsions based on 2,4/2,6- diisocyanato-1-methyl-benzene (TDI) ...... 86

Table 4.22 Labeling, composition, TIDT, T50%, Tmax, and residue at Tend of representative PUA copolymers ...... 87 Table 4.23 Labelling, emulsion concentration, warp and weft wise (%) improvement in tear strength of textile fabric coated with H12MDI, PCL/PEG, 2-HEMA and BA based PUA emulsions...... 102 Table 4.24 Labeling, emulsion concentration, warp and weft wise (%) improvement in tear strength of textile fabric coated with IPDI, PCL/PEG, 2-HEMA and BA based PUA emulsions...... 103 Table 4.25 Labeling, emulsion concentration, warp and weft wise (%) improvement in tear strength of textile fabric coated with TDI, PCL/PEG, 2-HEMA and BA based PUA emulsions...... 104

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Table 4.26 Labeling, emulsion concentration, rubbing fastness, washing fastness and light fastness of textile fabric coated with H12MDI, PCL/PEG, 2-HEMA and BA based PUA emulsions...... 106 Table 4.27 Labeling, emulsion concentration, rubbing fastness, washing fastness and light fastness of textile fabric coated with IPDI, PCL/PEG, 2-HEMA and BA based PUA emulsions...... 108 Table 4.28 Labeling, emulsion concentration, rubbing fastness, washing fastness and light fastness of textile fabric coated with TDI, PCL/PEG, 2-HEMA and BA based PUA emulsions ...... 109 Table 4.29 Formulations of polyurethane acrylate emulsions, pilling evaluation and emulsion stability ratings of coated textile fabrics ...... 115 Table 4.30 Physical characteristics of representative PUA samples of AR-0-PMPGlu and AL-0- PMPGlu copolymer series ...... 120 Table 4.31 Chemical resistance of cured films of representative PUA samples of AR-0-PMPGlu and AL-0-PMPGlu copolymer series...... 121 Table 4.32 Abrasion test results of representative PUA samples of AR-0-PMPGlu and AL-0- PMPGlu copolymer series (vacuum and dry heating oven cured) ...... 122

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List of Abbreviations

% Percent 0C Celsius centigrade 2-EHA 2-Ethylhexylacrylate 2-HEA 2-Hydroxy ethyl acrylate 2-HEMA 2-Hydroxyethyl methacrylate AAL Allyl alcohol AATCC American association of textile chemists and colorists AC-PU Acrylic polyurethane AEAPTMS N-(2-aminoethyl)-3-aminopropyltrimethoxysilane AFM Atomic force microscopy APS Ammonium persulphate ASTM American standard testing methods ATESPC Allyl 3-(triethoxysilyl) propyl carbamate ATO Antimony doped tin oxide BA Butyl acrylate BD Butanediol cm-1 Per centi meter Cps Centipoises CRL Candida rugosa lipase

DBTDL Dibutyltin dilaurate (C32H64O4Sn) DGEBA Bisphenol-A diglycidyl ether DMBA Dimethylol butanoic acid DMF N,N- Dimethylformamide DMPA Dimethylol propionic acid DMTA Dynamic mechanical thermal analysis DSC Differential scanning calorimetry DTG Differential thermogravimetric EB Electron beam xv

FT-IR Fourier transforms infrared spectroscopy FT-IR-ATR Fourier transforms infrared-attenuated reflectance Fw Formula weight g/L Gram per liter GMA Glycidyl methacrylate

H12MDI Methylene bis (4-cyclohexylisocyanate) HBP Hyper-branched HBPE-3G Third generation hyper branched HBPE-OH Hyper-branched polyester end capped with hydroxyl groups HB-UA Hyper-branched polyurethane acrylate HDDA 1, 6-hexanediol diacrylate HDI Hexamethylene diisocyanate HMDA 1,6-hexamethylenediamine hrs. Hours HUA-HC Hybrid urethane acrylate hydrolytic condensate ICPTES (3-isocyanatopropyl) triethoxysilane IPDI Isophorone diisocyante, IPN Interpenetrating polymer networks ISO International organization for standardization kg-1 Per kilogram KHz Kilo hertz kJ Kilo joule KPS Potassium persulfate LC Liquid crystal LIPN Latex interpenetrating polymer networks MEK Methylethyl ketone Mg Milligram Mm Millimetre MMA Mol Mole MW Molecular weight xvi

Nm Nano meter NMR Nuclear magnetic resonance Pa Pascal PCD Polycaprolactone diol PDI Polydispersity index PDSC Photo differential scanning calorimetry PEG Poly (oxyethylene) PETA Pentaerythritol triacrylate

Pf Final unsaturation conversion PMMA Poly (methyl methacrylate) PMPGlu Poly (2-methyl-1,3-propylene glutarate) PP Prolypropylene PPO oxides PSD Particle size distribution Pt-BA Polytert-butylacrylate PTMG Polytetramethyleneetherglycol PU Polyurethane PU/AC Polyurethane/polyacrylate PUA Polyurethane PU-PTFEMA Polyurethane-poly (2,2,2-trifluoroethyl methacrylate) PVA Polyvinyl alcohol PVC Pigments to volume concentrations

RP max Maximum photo polymerization rates Rpm Rotations per minute S Siemens s-1 Per second SAXS Small angle X-ray scattering SEC Size exclusion chromatography SEM Scanning electron microscope

T50% Temperature at 50 % weight loss TDI Toluene diisocyanate xvii

TEA Triethylamine TEM Transmission electron microscopy

Tend Temperature at the end of degradation Tg Glass transition temperature TGA Thermo gravimetric analysis THEIC 3-(2-hydroxyethyl) isocyanurate

TIDT Initial decomposition temperature

Tm Melting temperature

Tmax Temperature at maximum rate of weight loss TMPTA Trihydroxy methyl propane triacrylates UAMA Urethane acrylic macro-anionomer UDMA Urethane dimethyl acrylate UV Ultra violet UV-PUD UV curable polyurethane dispersions UV–VIS–NIR Ultra violet–visible–near infrared VAc Vinyl acetate VOC Volatile organic contents VTPU Vinyl terminated polyurethane prepolymer w/w Weight/Weight WAXD Wide angle X-ray differaction WHPUD Water-borne hyper-branched polyurethane acrylate WPU Water-borne wt. Weight XPS X-ray photoelectron spectroscopy XRD X-ray diffraction

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List of Appendices

Appendix 1 ...... 134 Appendix 2 ...... 142

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Abstract

In this modern era, a world without synthetic is incredible. In spectacle of rapidly depleting natural resources, synthetic polymers have become an elegant alternative. Polyurethanes are one of these, that have been developed as an exclusive class of polymers with wide variety of applications in foams, , coatings, , textile finishing, automotive, insulation and footwear industries. Polyurethane based coating systems have a proven record in the coatings industry dominating the market in some applications because they exhibit a high level of quality. These coatings allow high variability of the property profile and can be fitted for a specific application by changing, the chemical structure of the constituents or the molecular weight and degree of branching of the chains. Polyurethane coatings are in general more expensive. Polyurethane chemistry permits the amalgamation of functional groups which can be used to modify properties. To take advantage of polyurethane film-forming properties, a combination with cheaper materials is now a common practice in the coating market, leading to new different products. Of the most popular second components, one is the acrylic dispersion and the new product combines the excellent mechanical and chemical properties of the polyurethane resin with the low price of the acrylic component. In current project polyurethane coatings were prepared by the copolymerization of polyurethane with the butyl acrylate. Different series of polyurethane acrylate copolymers containing different monomeric constituents i.e. diisocyanates and polyols, in different proportions with butyl acrylate were synthesized by emulsion polymerization and characterized successfully. The synthesis of these copolymers was completed in three steps i.e. synthesis of polyurethane prepolymers, introduction of unsaturated sites at the free reactive ends of polyurethane prepolymers and copolymerization of vinyl terminated polyurethane prepolymers with n-butyl acrylate. Also, these copolymers were applied on textile fabric as finishing agent and their effect was assessed by different standard textile tests.

Chapter 1

2

1 Introduction

Polymers as a gift of nature are with us since the emergence of life on this universe, but man realized it much later. Prior to the early 20th century, chemists doubted the existence of molecules having molecular weights greater than a few thousand. This restrictive view was challenged by Hermann Staudinger, a German chemist with experience in studying natural compounds. Natural polymers devised the basics of life. Human beings are enjoying life with these natural polymers like wood, rubber, cotton, wool, leather, silk etc. Polymers are large molecules composed of repeated chemical units. The term polymer was derived from the Greek roots poly (many) and meros (part). However the history of polymer science and synthetic polymers is not so aged, its roots just grow to the mid of 19th century, with accidental innovation of . However, it was growing with a very slow rate till the start of 20th century. The World War II helped to outline the future of polymers. The Wartime demands and shortfalls encouraged scientists to search for substitutes and materials that exceeded currently available materials. So, during and after the war a lot of new materials were urbanized, spurred by needs in the electronics, medical, defense, transportation, communications, food, aerospace, and other industries. Until now this is an ever growing field of science and in this modern epoch, a world without synthetic polymers is incredible. Moreover, in view of rapidly depleting natural assets, synthetic polymers have become a smart alternative. Synthetic polymers can be made to resemble and substitute diversified range of materials as metals, wood, glass, stone, cloth, rubber, cardboard and leather etc. A wide range of synthetic polymers with variety of specialties is available in the market; few of these are , polyolefins, polydienes, , vinyl polymers, polyurethanes, , and acrylic polymers etc. During the growing age of polymers, before the mid of 20th century, polyurethanes (PU) were discovered by Otto Bayer and co-workers as an exclusive class of synthetic polymers with wide variety of applications (Herrington and Hock, 1998; Woods, 1990). Applications of polyurethane are so wide spread because their properties can be readily tailored by the variation of their components. The urethane linkage is formed by the reaction of an isocyanate group (NCO) of one reactant with the alcoholic group (OH) of another component. The microstructure of a PU block itself is generally known to be composed of two different phases. One phase has been built of 3 hard or rigid urethane-type segments. These are mainly composed of urethane groups originating from diisocyanates and may also contain urea groups if, a low-molecular weight diamine chain extender is used. These are in a glassy or semi-crystalline state; provide dimensional stability by acting as thermally reversible and multifunctional cross-links and also as reinforcing fillers. The other one are soft domains which have built of flexible segments derived from polyol components, these are in a viscous or rubbery state which provide the elastomeric characteristics to the polyurethane chain (Oprea, 2002). The hard segments are correlated to the hardness, strength, durability and toughness of polymer and the soft segments establish the flexibility and the glass transition temperature (Tg). By controlling variables such as the functionality, chemical composition and the molecular weight of the different reactants in PU, an extensive class of materials with significantly varying properties can be obtained. This flexibility enables PU to find use as synthetic polymers in foams, elastomers, coatings, sealants, and based products. Some of the applications of polyurethanes lie in the textile finishing, automotive, furniture, construction, thermal insulation and footwear industries. Polyurethane based coatings have established evidence in the coatings industry dominating the market in some applications because these coatings can exhibit a high level of excellence. Also these coatings present good weather stability and resistant to different chemicals and common solvents. The films of PU demonstrate very good mechanical properties and offer the ideal blend of hardness, flexibility and scratch resistance. These striking characteristics of PU coatings results from the primary and secondary structures of the PU chains. The polymer chains are resistant to solvents, and chemicals due to urethane linkages. Hydrogen bonds are responsible to form a stable physical network inside polymeric chains. These hydrogen bonds and the two phase microstructure of the PU chains, ensure the excellent mechanical properties of these films. Solvent-borne PU coatings have been used for many years in a wide variety of applications where excellent presentation is required in terms of film appearance and resistance properties (Aznar et al., 2006). However volatile solvents in these coatings are tiresome for the consumers. That’s why, at this moment the requirement is of the products with reduced volatile emission and a great concern is observed to develop the without or with low volatile emission products and technologies. There are a number of options for producing low volatile emission coatings counting water-borne polyurethanes (WPU). These new water-borne coatings must compete with the property sketch of similar other solvent-borne coatings. 4

The water-borne polyurethanes are introduced as environment-friendly materials with good adhesion, elasticity, and chemical and solvent resistance. These are non-toxic and non-flammable materials (Rahman et al., 2007). Based on water, they are VOC-free (volatile organic contents) or of low VOC emission. These WPU materials have been extensively applied in , coatings, surface finishing, paper and textile industries (Kim and Shin, 2002; Zhu et al., 2008). The WPU technology is now growing at a prompt rate and is a very common practice in the industry (Aznar et al., 2006). The scientific writings and other professional text have been reporting potential applications of WPU binders or vehicles not only for the production of environmentally friendly lacquers and also for impregnation of materials with considerably high surface areas like fibrous mineral fillers, and adhesive for powdered ceramic materials as well (Król et al., 2005). However PU coatings are in general more expensive and in some applications there are cost limitations. The combination of PU with a low cost material is now a common routine in the coating market, leading to variety of new products. One of the most popular second components is the acrylic moiety. Acrylic polymers are known to have superior water resistance, wearing resistance, adjustable mechanical properties and low cost, though they have low solvent and abrasion resistances. Combination of polyurethanes with acrylics is expected to be valuable to increase the performances of the resulting materials (Zhu et al., 2008). Acrylic polymer emulsions have been extensively used in leather industry as coatings, also as paper and textile finishes (Chai et al., 2008). These products combine the excellent properties of the PU and acrylic components with adjustable prices (Dzunuzovic et al., 2005). Polyurethane acrylates (PUA) are comb-like materials which can potentially merge the high abrasion resistance, toughness, tear strength, chemical and solvent resistance, and good low temperature properties of polyurethanes with the good optical properties, water resistance, wearing resistance and weather ability of the acrylates. A wide variety of properties, depending on the frequency of the arrangement of acrylic structural units on the macromolecular chain, is obtained; such as anticorrosive protective films and finish materials for leather industry, bending matter for magnetic media, mounts for printing ink coating for optical fibers, carbon fibers, adhesives, gas and liquid separating membranes, materials for medical usages, etc. (Oprea et al., 2000). The PUA hybrids have become one of the major types of binders used in the formulation of coatings for many substrates due to their high performance properties and environmental advantages. Recently the incorporation of acrylic component into PU dispersions has been widely 5 studied by numerous researchers (Sebenik and Krajnc, 2004; Šebenik et al., 2003; Kim et al., 2002; Kukanja et al., 2002; Wu et al., 2002; Wu et al., 2001). Different researchers account excellent statements about the characteristics of polyurethane acrylates. Also among the UV- curable coatings, PUA have gained more and more attention and rapid development due to a wide range of excellent application properties (Xu et al., 2006). Therefore, studies on polyurethane modifications by acrylic monomers have seen a significant progress in recent years (Zhu et al., 2008). There are some research groups dealing with combinations of polyurethane with acrylic dispersions, which incorporate polyurethane as a co-binder of acrylic emulsions, dispersants (Huang et al., 1997), physical mixtures and composites (Jan et al., 1995). Physical blends of the two different polymeric systems are an accepted approach to combine the favorable attributes of each of polymer. However, in many cases these blends present the expected characteristics and compromise the superior performance properties because of the incompatibility of the two systems in which the different polymers are present as separate particles. A more elegant way to obtain this balance is to synthesize the polyurethane acrylate copolymer (Wu et al., 2002). In these systems, both components are present in a single polymers molecule exhibiting combine advanced properties (Athawale and Kulkarni, 2009). According to the research writings a chemical coupling between the urethane and the acrylic components have established, and these systems are known as polyurethane acrylates or acrylic polyurethane hybrids (Kim and Lee, 1995, Kim and Suh, 1996). Unsaturated polyurethane resins are reacted with acrylic monomers in the presence of water as a solvent in a special copolymerization process to produce organic solvent free polyurethane acrylates. This type of chemical combination was also used to prepare UV-curable polyurethane acrylates composites and emulsions (Kim and Kim, 1998; Kim et al., 1996a; Kim et al., 1996b; Song et al., 1996). These hybrid systems have generated binders with better technological properties in coatings than those obtainable from physical mixtures of the two polymers or composites, and several studies were performed in connection with this. It was reported that they have improved resistance properties (Aznar et al., 2006). Keeping in view all of these metaphors, this dissertation was designed in which polyurethanes were copolymerized with acrylates. Polyurethane acrylate copolymers were synthesized with varying compositions by three step synthesis process with water as solvent. To establish the chemistry and to evaluate the efficacy range, synthesized copolymers were subjected to special tests and characterized by different

6 sophisticated techniques e.g FT-IR, DSC, TGA etc. Foremost aims and objectives of this project were following: • To study the structural influence of different acrylates on thermo chemical behavior of polyurethanes. • To investigate the role of chemistry of isocyanates (aliphatic and aromatic) in the morphology and thermo chemical behavior of polyurethanes. • To examine the contribution of different polyols (polyester & polyether) in the morphology and thermo chemical behavior of polyurethanes. • To contribute the economy of Pakistan by establishing a source of local technology in the textiles. • Characterization of copolymer by different spectroscopic and thermal techniques.

7

Chapter 2

8

2 Review of Literature

The polyurethanes have been developed as an exclusive class of synthetic polymers with wide range of applications in foams, elastomers, coatings, sealants, textile finishing, automotive, insulation and footwear industries. The urethane linkage is formed by the reaction of an isocyanate group of one reactant with the alcoholic group of another component. The microstructure of a polyurethane block itself is usually known to be composed of different phases, i.e. hard urethane-type phase and soft phase. The PU chemistry also allows the amalgamation of functional groups which can be used to adjust the properties. The Polyurethane- based coating systems exhibit a high level of quality offering good weather stability. The PU films have very good mechanical properties and provide the ideal balance of hardness and flexibility, even at low temperatures. Since few decades water-borne polyurethanes are introduced as environment-friendly materials with good adhesion, elasticity, and chemical and solvent resistance. These are non-toxic and non-flammable materials. Based on water, they are VOC-free or of low VOC emission. But PU coatings are in general more expensive. To take advantage of polyurethane film-forming properties, a combination with cheaper materials is now a common practice in the coating market, leading to novel different products. Of the most popular second components, one is the acrylic moiety and the new product combines the excellent mechanical and chemical properties of the PU with the low price of the acrylic component. Here is a brief review discussing the progress of polyurethane acrylates during the last decade. Wu et al. (2001) synthesized polyurethane acrylic composite lattices with polyurethane dispersions as the seed. According to the results shown by Fourier transform infrared coupled with attenuated reflectance (FT-IR-ATR) films of composite lattices were rich in polyurethane content at air facing and substrate facing surfaces, in comparison with their average composition. Furthermore, the substrate facing surface had even more polyurethane than the air facing surface. It was also confirmed by the X-ray photoelectron spectroscopy (XPS) that the polyurethane component preferentially migrated to the surface layer of the films from the bulk, and it was more pronounced phenomenon since the films of blend lattices. Following these results it was

9 suggested that some orientation had occurred in synthesizing the composite lattices and/or after film formation. This structure and composition endow with both surface properties, such as mar- resistance, adhesion, wet ability from pure polyurethane, and film hardness from acrylic moieties. Decker et al. (2003) synthesized a water based dual-cure urethane-acrylate oligomers by polycondensation of monomers bearing hydroxyl, isocyanate and acrylate groups. To obtain a stable aqueous dispersion, isocyanate groups were protected by a blocking agent and carboxylate groups were grafted on the oligomer chain. Dry films were obtained after water release by a brief heating. Then these films were cured either by a short UV exposure in the presence of a photoinitiator to provoke the polymerization of the acrylate double bonds, or by heating up to 150 0 C to release the isocyanates and promote the polycondensation by reaction with the hydroxyl groups, and also by a combination of UV and thermal cure. Both processes were examined quantitatively by infrared spectroscopy (FT-IR) to evaluate the influence of the temperature on the reaction rate and on the cure extent. It was found that the newly developed water based dual- cure coatings were quite resistant to accelerated weathering due to their aliphatic structure and high crosslink density. Their light stability was significantly improved by the introducing a hydroxyphenyltriazine UV absorber and a hindered amine radical scavenger. Huang et al. (2003) prepared a novel polyurethane acrylate porous polymer by emulsion polymerization. It was claimed in this study that compared with the traditional phase inversion method; this new method could eliminate the pollution produced in process of extraction and also decrease the cost of production. The porous polymers were immersed in 1 -1 molkg solution of LiClO4/PC (propylene carbonate) to form polymer electrolytes. The structural analysis of porous polymers and porous polymer electrolytes was carried out by using scanning electron microscope (SEM). The conductivity of the polymer electrolytes was as high as 10-3 S cm-1 which could be constructive in many practical electrochemical appliances. Park et al. (2003) prepared holographic polymer dispersed liquid crystals from photo-curable polyurethane acrylate of various structures and a nematic liquid crystal mixture upon curing the reactive diluents and hydroxy ethyl acrylate terminated (HEA) polyurethane prepolymers. Emphases had been made to improve the shrinkage and reflection efficiency of holographic grating during fabrications by altering soft segment length and hard segment structures of the prepolymer. It was observed that polyurethanes with short soft segment and flexible hard segment gave high volume shrinkage and reflection efficiency as well. It was interpreted in terms of 10 improved cross linking density and elasticity of polymer networks. Among three types of diisocyanates, isophorone diisocyante (IPDI), hexamethylene diisocyanate (HDI), and toluene diisocyanate (TDI) being used as hard segments of polyurethane, HDI gave the highest and TDI gave the lowest reflection efficiency. Chain flexibility, high immiscibility and low viscosity of HDI with the aromatic liquid crystal (LC) molecules should provide clean phase separation from physical and chemical points of view. When the above two molecular parameters were considered together, it was found that the effect of diisocyanate structure was more pronounced when the soft segment length was short. This could be justified in this way, since with short soft segment, composition of soft segment became small, and the hard segments governed the properties of the composite films. Šebenik et al. (2003) reported that the choice of technique for introducing into the reaction stream containing PU dispersion could be a significant effect upon the hybrid particle structure, particle size and size distribution. To study this effect, aqueous acrylic–polyurethane hybrid emulsions were prepared by batch and semi-batch polymerization of acrylic monomer mixtures (butyl acrylate, methyl methacrylate and ) in the presence of polyurethane dispersion. The acrylic component was added in the monomer emulsion feed by batch and semibatch processes. The weight ratio between acrylic and polyurethane components was assorted to acquire different emulsion properties, microphase structure and mechanical film properties. It was found that the average particle size increased with increasing the acrylic/polyurethane ratio. By batch process particles of larger than average size and even higher than average molecular weights were produced. On the other side Koenig hardnesses decreased with increasing acrylic/polyurethane ratio. It was concluded that acrylate polyurethane hybrid emulsions prepared by the semibatch process exhibit higher latex stability and improved application performances as compared to the emulsions obtained by common batch process. Asif and Shi (2004) investigated a novel water-borne hyper branched polyurethane acrylate for aqueous dispersions (WHPUDs) based on hydroxy-functionalized hyper branched aliphatic polyester BoltornTM H20. The effects of structural composition and cross linking density were evaluated in terms of thermal degradation, swell ability by water, viscosity changes as well as morphology by transmission electron microscopy (TEM). It was found that the swell ratio increased with the higher content of ionic group, which was because of the increased total surface area of particles. The data of thermo gravimetric analysis (TGA) for cured WHPUD films 11 displayed good thermal stability with no significant weight loss until 200 0C. The evaluation of activation energies presented the range 154–186 kJ mol-1. It was experienced that an increase in hard segment content aggravated the increases in activation energy and thermal degradation temperature of water-borne dispersions. The average particle sizes of aqueous dispersions as exposed by the transmission electron photographs were in the range of 30–125 nm. Due to the amplification of the stabilization site, the particle size was decreased as the carboxyl group content and degree of neutralization was increased. It was found that the viscosity of WHPUDs increased quickly with increasing the degree of neutralization. Furthermore, water contributed a favorable viscosity reduction effect. Decker et al. (2004) studied the light stability of water based UV-cured polyurethane-acrylate (PUA) coatings in an accelerated QUV-A weatherometer. Ultrafast polymerization of the acrylate double bond by intense illumination, and the chemical changes occurring by the photo ageing of 30 mm thick clear coats were monitored by infrared (IR) spectroscopy. It was found that the UV- curing reaction was barely affected by the addition of the Tinuvin radical scavengers and UV absorbers were required to improve the light stability of water based UV-cured PUA coatings. The α-hydroxy phenyl ketone, photo initiator was revealed to disappear quickly upon UV curing and early QUV exposure, consequently having no detrimental effect on the weathering resistance. It was considered that the most sensitive to photo degradation is urethane linkage (C-NH). These water based PUA coatings were established to be as resistant to weathering as typical UV cured PUA coatings. In the existence of light stabilizers, these undergo only minor chemical changes after almost 4800 h QUV-A ageing, the surface erosion was being restricted to a just few micron thick layer. The practical consistency of the UV-absorber after such heavy exposure ensured a prolonged UV-screen effect of the protective coating. Water based UV-cured PUA coatings were found to be more challenging to hydrolysis than melamine-acrylate thermosets. Tasic et al. (2004) presented findings about synthesis and investigation of UV-curing of multifunctional hyper branched polyurethane acrylate (HB-UA) based on aliphatic hyper branched polyesters (HBP) and glycol acrylate. Their physical and thermal properties were evaluated and used to establish the relationships between structure and properties of cured coatings. It was observed that introduction of a flexible ethoxylated spacer between HBP core and acrylate end groups reduced the steric hindrance by moving the cross linkable acrylate groups away from HBP core and in this way its reactivity was increased. These ethoxylated HB- 12

UA’s been very reactive and did not show oxygen inhibition owing to the presence of abstract able H-atoms in the α-position of the ether links. The formulated coatings combined a high crosslink density with elastic segments between cross links, so that resulting in good compromise between hardness and flexibility. It was suggested that these coatings have the potential to be applied in different UV-curing applications. Xu et al. (2004) synthesized a novel UV-curable hyperbranched polyurethane acrylate (HUA) and found to polymerize rapidly in the presence of 5 wt. % benzophenone under UV exposure. The photo polymerization kinetics of HUA, toughening effect for polypropylene (PP) and morphological structures and thermal behavior were investigated by different relevant techniques. The obtained results revealed that the maximum photo polymerization rate increased with increasing temperature up to 140 0C, while decreased at above 150 0C. The activation energy of 19 kJ mol-1 was found for the photo polymerization at below 140 0C from the Arrhenius plot, while it was negative at above 150 0C. The inclusion of 5 wt. % HUA greatly enhanced the notched impact strength of PP matrix with a slight progress in the tensile strength, without obvious turn down in breaking elongation. These results correlate well with scanning electron microscopy (SEM) examination. UV irradiation of PP/HUA blends resulted in the increase of the impact strength of PP matrix. A reduction of perfection of PP crystals and decrease of spherulite size in the PP/HUA blends was due to the nucleation role of HUA particles. Zhang and Zhang (2004) successfully prepared the water-borne polyurethane (WPU)/poly (methyl methacrylate) (PMMA) through 60Co-γ ray radiation-induced seeded emulsion polymerization. The kinetic curves of the synthesis of water-borne polyurethane were obtained in methyl methacrylate (MMA) medium and in acetone medium, correspondingly. The Fourier transform infra red (FT-IR) spectra were collected to scrutinize the grafting efficiency of the PMMA on WPU backbone. It was found that the grafting efficiency of WPU/PMMA composite polymer initiated by γ-ray was larger as compared to that initiated by K2S2O8. Dzunuzovic et al. (2005) synthesized urethane acrylate resins based on partially modified aliphatic hyperbranched polyesters (HBP). Hyper branched polyesters (HBP) of the second and the third generation were formulated from 2,2-bis(hydroxymethyl) propionic acid and di- trimethylol propane. Soybean fatty acids were used for the alteration of certain amount of OH end-groups. The urethane acrylates with diverse degrees of acrylation was prepared by reaction of partially modified HBP and different amounts of NCO adduct which had been previously 13 obtained by the reaction of isophorone diisocyanate and 2-hydroxyethyl acrylate. The synthesized samples were characterized by different spectroscopic techniques, and rheological properties of uncured samples and thermal and mechanical properties of UV cured urethane acrylates were also evaluated. It was observed that the modification of OH end-groups with soybean fatty acids resulted in a rapid decrease in viscosity of HBP. Also results presented that the examined properties of urethane acrylates were dependent on the degree of acrylation. After irradiating, the properties of the cured samples were affected by the additional cross-linking, caused by reaction of double bonds from unsaturated fatty acids. Król et al. (2005) presented findings from the study on supermolecular structures which produced spontaneously on the surface of a solid urethane acrylic copolymer. The polyurethane prepolymer was synthesized in the polyaddition process of 2,4- and 2,6-tolylene diisocyanate (TDI), polycaprolactone diol (PCD) and 2,2-bis(hydroxymethyl) propionic acid, and then it was reacted with 2-hydroxyethyl acrylate (HEA) and 1,6-hexamethylenediamine (HMDA). At the final pace, thus, obtained urethane acrylic macro-anionomer (UAMA) was subjected to free radical copolymerization with methyl acrylate and butyl acrylate to produce the aqueous emulsion of graft polyurethane polyacrylic copolymer. The size exclusion chromatography (SEC) was used to assess distribution of molecular weights in the obtained copolymer before its cross-linking in air. Complexity of supermolecular structures was analyzed by the differential scanning calorimetry (DSC) and small angle X-ray scattering (SAXS) techniques. Also, dispersion in the continuous phase of the domains was evaluated with the help of the atomic force microscopy (AFM) method. After this study it was suggested that the use of ionomers, and exclusively urethane acrylic anionomers, in the production of binders for green ceramics is expected to be valuable since polar ionic bonds can be formed between the polymer and the surface of Al2O3 grains which are alkaline. Ren et al. (2005) prepared a novel polyurethane acrylate porous gel electrolyte by a new method, emulsion polymerization. As compared to the traditional phase inversion method, this new method eliminated the pollution from solvent and also decreased the cost of production. The emulsion concentrations had an important effect on defining the morphology of porous membranes, predominantly maintaining the size of the cavities. The morphology and swelling properties of the porous polymer membranes were examined. It was observed that the porous membranes, prepared by the emulsion polymerization method, could absorb large quantities of 14 electrolyte solution to form porous gel electrolytes. These gel electrolytes had good solvent withholding capacity and high ionic conductivity. The amount of liquid electrolyte designed the conduction pathways of porous gel electrolytes. When conduction pathways were established in the liquid phase, the ionic conductivity increased swiftly. Šebenik and Krajnc (2005) prepared aqueous acrylic polyurethane (AC–PU) hybrid emulsions by semibatch emulsion polymerization of methyl methacrylate (MMA) in the presence of four different polyurethane (PU) dispersions. The polyurethane dispersions were synthesized with isophorone diisocyanate (IPDI), poly(neopentyl) , polytetramethyleneetherglycol (PTMG), butanediol (BD), and dimethylol propionic acid (DMPA). Methyl methacrylate was added in to the monomer emulsion feed. The effect of different PU seed particles was studied on the rate of polymerization, the particle size and distribution, the number of particles, and the average number of radicals per particle. The polyurethane inflexibility was controlled by varying the polyol chemical structure, the polyol molecular weight (MW), and by adding BD. Also, the monomer feed rate was varied to investigate its influence on the process. It was observed that the polyurethane particles that had been prepared with a higher MW polyol swelled more with MMA before the monomer starved conditions occurred. There were no significant discrepancies between the series with different polyurethane seeds in the monomer starved conditions. The average particle size was increased, but the total particle number in the reactor was constant and similar to the number of polyurethane particles in the initial charge. The average number of radicals per particle was also increased. The semibatch emulsion polymerization of MMA in the presence of polyurethane particles was better as compared to the system with a fixed radical concentration. Xu and Shi (2005) synthesized a series of UV curable hyper branched polyurethane acrylates (HUAs) by modifying the hyper branched polyester end capped with hydroxyl groups (HBPE- OH) using urethane acrylate prepared from toluene diisocyanate and 2-hydroxyethyl acrylate. These products, which were in the form of white powder at room temperature, had high melting viscosity. However, this high viscosity could be decreased rapidly by adding co-monomer or increasing the temperature. Final unsaturation conversion (Pf) and maximum photo polymerization rates (RP max) were investigated in the presence of a photoinitiator. The results presented that addition of an excess of 1, 6-hexanediol diacrylate (HDDA) as a co-monomer resulted in the decreases in RP max and Pf. The higher RP max and Pf were obtained with the HUA 15 prepared from the modification of HBPE-OH by succinic anhydride as compared with that by phthalic anhydride. From the results of dynamic mechanical thermal analysis (DMTA), these hyper branched prepolymers had good miscibility with HDDA. Additionally, the HUA based resin with 20 wt. % HDDA had the highest softening point and glass transition temperature owing to its high cross-linking density. Aznar et al. (2006) prepared glossy topcoat one-pot exterior formulations using water-based polyurethane acrylates hybrid binders as well as its properties were assessed through different conventional tests. In this study polyurethane (PU) anionomer having 2-ethoxy methacrylate terminal groups was prepared following a prepolymer mixing route. In aqueous solution this prepolymer was chain extended and after introducing acrylic monomers radical polymerized. were formulated by using titanium dioxide as exclusive pigment. Panels layered with air- dried paints with three different pigments to volume concentrations (PVC) were subjected to standardized tests such as flexibility, gloss, adhesion and color determination. Accelerated weathering tests were performed to assess changes in properties, especially gloss and color of coated panels. It was observed that air-dried formulations based on hybrid polyurethane/acrylic with 50 wt. % of acrylic constituent, showed a high gloss as 70 and the relative gloss change was lower than the pure solvent based acrylic and polyurethane paints after accelerated weathering test. The results found in this study indicated that depending on the end use of the paint it is possible to substitute pure polyurethane water-based binders with hybrid polyurethane/acrylic binders; consequently a more economical product with good finishing and durability is available. El-Molla and Schneider (2006) prepared some novel aqueous binder of polyurethane acrylate based on either polyethylene glycol or glycerol ethoxylateco-propoxylate having zero volatile organic compounds. These were used for preparing printing paste for screen printing of all types of textile fabrics with pigment dyes. It was observed that the highest color strength was achieved for samples printed using polyurethane acrylate based on glycerol ethoxylate-co-propoxylate as a binder; this is factual irrespective of the type of fabric used. However lower value of color strength was obtained for samples printed using Ebecryl 2002 as a commercial binder. Also, polyurethane acrylate based on PEG2000 was better than polyurethane acrylate based on

PEG1000+2000, unless in case of screen printed wool, the inverse was true. It was concluded that novel prepared aqueous oligomers (binder) of polyurethane acrylate based on either polyethylene glycol or glycerol ethoxylateco-propoxylate can be applied safely for preparing printing paste for 16 screen printing of all types of textile fabrics using pigment dyes. Goods printed with this system showed satisfactory fastness properties and the hand of printed goods was soft. Kim et al. (2006) designed and synthesized UV curable polyurethane dispersions (UV-PUDs) with different prepolymer chain length, different types of capping agent (2, 3-epoxy-1- propanol (glycidol) and 2-hydroxyethylacrylate (HEA) and ionic center dimethylol butanoic acid (DMBA) and dimethylol propanoic acid (DMPA). Much finer dispersion was obtained with DMBA as compared to DMPA owing to the greater steric hindrance of large pendant group in opposition to the attack of isocyanate groups to the carboxylic groups. Hard and soft segments of UV-PUDs were in general phase mixed. However, a tendency of phase separation was noticed when the molecular weight increased. UV-PUDs appropriately combined the advantages of PU dispersion and UV cure resulting in high hardness, high modulus, tack free prior to cure, high solvent resistance and low water swell particularly with high glycidol content despite the fact that the elongation at break was high over 200 %. Pujari et al. (2006) hydrophilized polypropylene (PP) by coating followed by UV curing of a blend of 2-hydroxyethyl methacrylate (HEMA) terminated polyurethane prepolymer and glycidyl methacrylate (GMA). This process led to construction of a hydrophobic membrane with increased biocompatibility, surface hydrophilicity and stability. On this membrane Candida rugosa lipase (CRL) was covalently immobilized using 5 % glutradehyde as a cross linking agent for post immobilization stabilization of enzyme. This membrane was placed in a batch membrane reactor where a model esterification of oleic acid with octanol was investigated. The bio catalytic membrane gave a specific activity of 796.27 units/mg and 90.26 % activity yield at optimum conditions. Furthermore, retention of specific activity was 85.10 %. It was observed that the bio catalytic membrane retained about 84.23 % of its synthetic activity after six cycles. Sugimoto et al. (2006) prepared interpenetrating polymer networks (IPNs) and IPN composite materials by in situ polymerization of urethane dimeth acrylate (UDMA) and bisphenol-A diglycidyl ether epoxy resin (DGEBA) with or without silica nano particles. The physical properties of the resulting IPN composites and IPNs materials were evaluated by different respective tests. The IPNs presented high transparency and higher elastic modulus and strength as compared to each homopolymer at the ratio of UDMA/DGEBA, 70/30. The IPN composites retained high transparency even after the addition of silica nanoparticles. Furthermore, elastic modulus and surface hardness of the IPN composites was increased with increasing silica content. 17

Therefore it was expected that these hybrid materials are structural materials or engineering materials. Xu et al. (2006) prepared an organic–inorganic hybrid urethane acrylate hydrolytic condensate (HUA-HC) through sol–gel method with an acid catalyst of low concentration from a hybrid urethane acrylate prepolymer (HUA), which was a difunctional silane containing hydrolysable ethoxy silane groups (Si–OEt). The photo polymerization kinetics was studied by photo differential scanning calorimetry (PDSC) results showed that HUA-HC had a faster apparent photo polymerizaton rate and a higher conversion of double bonds than HUA under 72 °C due to the environs of double bonds in the former. Though, HUA-HC showed a slower apparent photo polymerizaton rate and a poorer conversion of double bonds than HUA at higher temperatures above 72 °C, which ultimately indicated more extensive condensation between ethoxysilane (Si– OEt) and silanol (Si–OH) groups in HUA-HC as compared to HUA. Films of both HUA-HC and hybrid prepolymer cured by ultraviolet (UV) light showed high pencil hardness and outstanding abrasion resistance. Thick films (2-mm) HUA-HC and HUA cured by UV light showed high tensile strength. It was found that the cured HUA-HC film showed better performance than the cured HUA film in the evaluated aspects because of more inorganic Si–O–Si linkages in HUA- HC, which was also the rationale that HUA-HC film had higher decomposition temperatures and more residue as compared to HUA in thermal gravity analysis (TGA). El-Molla (2007) prepared polyurethane acrylate oligomers from isophorone diisocyanate (IPDI), mixture of polyethylene glycol (PEG) 1000 and 2000 and hydroxy ethyl acrylate (HEA) using dibutyl tin dilaurate as a catalyst. The and its application as a UV-curable binder for inks of ink jet printing and pigment dyeing of viscose, wool, polyester, cotton, and nylon 66 fabrics using pigment dyes were comprehensively investigated. It was observed that the prepared binder was of low viscosity (0.0042 PaS = 4.2 cP) at a shear rate of 10.0007 s-1. Moreover, the results presented that the aqueous UV-curable binder of polyurethane acrylate oligomer based on the combination of PEG1000 and PEG2000 can be applied safely for inks of ink jet printing. Also it can be used in pigment dyeing to give colored goods with soft handling and from good to excellent color fastness properties. Infra-red spectra of the mixture of PEG1000 and PEG2000 indicated some physicochemical changes in the structure, before and after the preparation of polyurethane acrylate oligomer.

18

Liu and Zhu (2007) synthesized polyurethane-poly (2,2,2-trifluoroethyl methacrylate) (PU- PTFEMA) triblock copolymer aqueous dispersions by three-step polymerization. At the first step, polyurethane prepolymers (PU) based on 2,4-toluene diisocyanate (TDI), polyether binary alcohol (N220), α,α-dimethylol propionic acid (DMPA) and hydroxypropyl acrylic acid (HPA), were prepared with butanediol (BD) as the chain extender. Subsequently neutralization and dispersion was carried out in water, where prepolymers were neutralized by the addition of triethylamine (TEA). The last pace was the seeded emulsion polymerization, where PU emulsion played role as seed, 2,2,2-trifluoroethyl methacrylate (TFEMA) as co monomer and potassium persulfate (KPS) as initiator. For the synthesis process of PU prepolymer, experimental results displayed that when reaction time (t1) was between 1 and 1.5 h, reaction temperature was between 60 and 80 0C. For the synthesis of copolymer aqueous dispersion, experimental results showed that when reaction time (t2) was between 8 and 10 h, reaction temperature was comparatively 0 high between 70 and 80 C, optimum K2S2O8 concentration was between 0.5 and 1.0 wt %, and TFEMA content was 10-15 wt %, for successful emulsion polymerization. Copolymer aqueous dispersion was homogeneous and stable even after 6 months. Subramani et al. (2007) synthesized organo functional silane-modified clay using an ion exchange technique. The progressions of the ion exchanged and of the yield were monitored as a function of the initial silane concentration by thermo gravimetric analysis (TGA). Qualitative evidence for the presence of chemically attached silanes on clay was provided by Fourier transform infrared spectroscopy (FT-IR). The grafted amount examined by thermo gravimetric analysis was in good harmony with the cation exchange capacity of pristine clay. Novel aqueous silylated (polyurethane-acrylic/clay) nano composite dispersions (SPUA-silylated polyurethane- acrylic) were prepared by using this silane-modified clay. It was revealed by the examinations that the clay platelets were generally intercalated or partially exfoliated in the SPUA matrix with a d-spacing of approximately 2-2.50 nm. With higher clay content SPUA/clay dispersion exhibited a marginal increase in the average particle size; though, silane-modified clay had a prominent effect. Moreover, the amalgamation of clay could also augment the thermal resistance and mechanical properties of SPUAs spectacularly through the reinforcing effect of organo philic clay. Clay did not affect the position and peak broadness of the glass transition temperature (Tg) of the soft or hard segment domains in the SPUA/clay films. However, the Tg of hard segment of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEAPTMS) clay nano composites were 19 elevated than those of commercial clay-based nano composites. Better water and xylene resistance results of the silane-modified clay nano composites showed that tri functional organo silane could be used as an effective modifier for clays. Bénard et al. (2008) presented photo ageing reactions and kinetics on long wavelength irradiation of an electron beam (EB) cured resin. The material studied was an aliphatic polyurethane acrylate resin. Infrared spectroscopy and UV–visible spectrophotometry were used to monitor the chemical photo reactivity of the polymer. Two stages of photo-oxidation were observed. In the first stage after EB polymerization the reaction of remaining acrylate functions led to additional cross linking and oxidized products. In the second step, oxidation rate was decreased and photo degradation products were produced at a constant rate. Across the coating thickness a heterogeneous distribution of residual acrylates was evidenced. In the depth of the film after photo ageing an oxidation profile was also observed. Chai et al. (2008) prepared anionic aqueous polyurethane dispersion by using carboxyl acid group. Then by soap-free emulsion polymerization method nanograde core–shell and cross linked inter penetrating network (IPN) structure polyurethane/polyacrylate composite latex (PUA) were synthesized with polyurethane dispersion as seed. Final products of core–shell composite PUA emulsion and the cross linked IPN composite PUA emulsion were characterized by different sophisticated techniques, and in the meanwhile their properties were compared. The results displayed that the particle morphology of PUA composite emulsion was inverted core–shell structure with polyurethane as the shell and with polyacrylate as the core. And the morphology of the cross linked IPN PUA emulsion was multi-core structure. The surface in core–shell PUA was rich in PU content. It was observed that the phase structure of the cross linked PUA was more uniform. Three glass transition temperatures were observed for the core–shell composite PUA, and there were two transitions for the film from the cross linked PUA. The TGA (thermo gravimetric analysis) curves of core–shell PUA and cross linked PUA exhibited two stages, the first stage owing to the thermal decomposition of hard segments in seed polyurethane; the second stage correspond to the decomposition of polyacrylate and soft segments in PUA. Tensile strength of the PUA films as well as the average diameter of the PUA composite emulsion particles was increased, with the increase of glycidyl methacrylate (GMA) content in PUA composite emulsions, but the elongation at break of the PUA films was decreased.

20

Wang et al. (2008) prepared UV-curable polyurethane acrylates (UVPUA). Effects of isocyanate type, soft segment length, reactive diluent type and level, annealing, quenching and different UV- cured degrees on the microstructure of UVPUA films were also been studied. It was observed that with increasing soft segment length, the degree of hydrogen bonding between soft segment and hard segments decreased, and microphase division of UVPUA became better. Crystallization due to soft segment appeared with its molecular weight exceeding 2000, when it was 4000; an even more evident melting peak in differential scanning calorimetry (DSC) curve was there. Assemble of hard segment domains and the perfection of phase separation were owing to the symmetry and regularity of isocyanate, whereas inflexible benzene ring was helpful to crystallize and to increase the glass transition temperature (Tg). Increasing the functional degree of diluent resulted in better phase separation, while on the converse, increase in the reactive diluent content led to the opposite due to a phase reversion. Microphase separation was poorer during quenching and annealing because of post-curing of 1, 6-hexanediol diacrylate (HDDA) at high temperature, however with the increase in UV-cured degree, the phase separation was better at start and then became worse. Zhu et al. (2008) prepared polyurethane–acrylic (PU–AC) hybrid latexes. Basic monomers for PU preparation were isophorone diisocyanate (IPDI), dimethylol propanic acid (DMPA) and polypropylene oxides (PPO) of different molecular weights. Acrylic monomers included butyl acrylate (BA), methyl methacrylate (MMA) and a cross linker, trihydroxy methyl propane triacrylates (TMPTA). Different important components in PU–AC latex preparation, such as initiator, DMPA, surfactants and PU/AC ratio, etc., were assorted, and their effects on latex properties were studied. There was a sharp increase in particle size in latexes done with 0.1 % of surfactant regardless of the nature of the surfactants used as compared to the surfactant free latexes. More increase in surfactant concentration, conversely, led to latexes with smaller particle size and narrower particle size distribution using an identical surfactant. It was observed that when quantity of the oil soluble initiator, azobis isobutyronitrile, was increased, acrylic monomers conversion was increased. It was attention-grabbing that PPO with long propylene oxides brought about larger particle size united with broader size distribution and less charge on particle surface; while lower DMPA content led to latexes also of larger size with broader size distribution but with more charges on particle surface. Acrylic monomer cross linker, TMPTA, contributed to narrower size distribution, diminish particle size, and poorer particle surface 21 charges. By increasing acrylic content in PU–AC latex, latex particle size was considerably increased accompanied by a remarkable increase in particle surface charges. Athawale and Kulkarni (2009) prepared aqueous polyurethane acrylic hybrid emulsions by semibatch emulsion polymerization of a mixture of acrylic monomers (styrene, butyl acrylate and acrylic acid) in the presence of polyurethane dispersion. Also, equivalent physical blends were arranged by mixing acrylic emulsion and polyurethane dispersion. The weight ratio between polyurethane and acrylic components was assorted to obtain improved performance properties and microphase structure of hybrid latexes. The physical blends and synthesized emulsion hybrids were characterized by Fourier transform infrared (FT-IR) spectroscopy, and thermo gravimetric analysis (TGA). The experimental results indicated better acrylic polyurethane compatibility in hybrid emulsions as compared to physical blends, resulting in improved mechanical and chemical properties. However the blend ratio 50:50 % (w/w) exhibited synergistic effects between the two polymers and demonstrated remarkable enhancement in various coating properties over other blend ratios and the individual resin components. Mishra et al. (2009) prepared the third generation hyper branched polyester (HBPE-3G) based polyurethane acrylate (HBPUA-32)/ZnO hybrid coatings, by modifying 16 hydroxyl groups of HBPE-3G with acrylic. The HBPE-32 was prepared from di-trimethylol propane (DTMP) and 2,2-bis (hydroxymethyl) propionic acid, converted into hybrid coatings by incorporating different amounts of nano ZnO powder into the polymer matrix. The percentage of condensation reaction and degree of branching was calculated from the results of 1H and 13C NMR spectra of the polyester HBPE-3G. These results suggested that there was nearly 71.6 % of condensation reaction and 46.6 % of branching had taken place. The deconvulated results indicated that the ZnO nano particles were inserted into the HBPUA-32 matrix and thus limit the chain mobility, and it was consistent with the dynamic mechanical thermal analyzer (DMTA) measurements of higher Tg. The TGA result showed that the onset degradation temperature, maximum weight loss and end set decomposition temperature were increased with increasing the ZnO content in the polymer. Correspondingly, the DMTA result suggested that the room temperature storage modulus, crosslink density, Tg and heterogeneity of the hybrid films increased with increasing ZnO content. X-ray diffraction (XRD) result suggested that assimilation of ZnO nanoparticles did not amend the regularity of the mother polymer and the scanning electron microscope (SEM) figures showed that nano sized ZnO powder were homogeneously dispersed in the polymer 22 matrix without agglomeration and form uniform clusters of ZnO particles. The coating property investigation suggested that the adhesion strength, abrasion resistance, and pencil hardness were increased with increasing the ZnO content. Athawale and Kulkarni (2010) synthesized polyurethane polyacrylate (PU/AC) core-shell hybrid latex by emulsion polymerization and interpenetrating hybrid latex by soap-free emulsion polymerization techniques, and compared their physico-chemical and thermo-mechanical properties. Infrared spectroscopy was used to examine the interactions between the PU and AC components in hybrid coatings. Mechanical properties were studied by measuring pencil hardness; shore A hardness and flexibility of dried films. Scanning electron microscopy (SEM) and particle size analyzer were used to explore the morphology of hybrid resins. Thermal profile of polymeric films was established by differential scanning calorimetry (DSC) and thermo gravimetric analysis (TGA). It was found that the core-shell hybrids had better physico-chemical and thermo-mechanical properties than latex interpenetrating polymer networks (LIPN) hybrids, attributing better interpenetration and entanglement between PU/AC in emulsion polymerization. Bao and Shi (2010) synthesized the hyper branched polyurethane acrylate (HPUA) through the addition of hyper branched polyurethane end capped by hydroxyl groups (HPU-OH), with the semi adduct urethane monoacrylate (IPDI-HEA). The HPU-OH was prepared by the reaction of isophorone diisocyanate with diethanolamine. The polydispersity index and number average molecular weight of the polymer were 1.24 and 7714 g mol−1, respectively. The HPUA was mixed with difunctional monomer TPGDA and epoxy acrylate EB600 in different ratios, and exposed to a UV lamp for photo polymerization in the presence of as a photo initiator at ambient temperature. It was observed that the photo polymerization rate and final unsaturation conversion reached to the highest values with just 5 wt % HPUA, while decreased with further addition. In case of mechanical properties tensile strength of UV-cured films was improved by addition of less than 10 wt % HPUA without harnessing the modulus. Moreover, the elongation at break was increased continuously with the content of HPUA. Also, the impact strength was greatly improved with the addition of HPUA. On the other hand, the Tg was decreased with the addition of HPUA. He et al. (2010) synthesized novel UV curable multi-functional polyurethane acrylate (PUA) containing 3-(2-hydroxyethyl) isocyanurate (THEIC) segment through three step reactions; the ring-opened reaction of ε-caprolactone with THEIC with the catalysis of tetrabutyl titanate 23

(TBT), the poly addition reaction between formed hydroxyl compounds and isophorone diisocyanate (IPDI) and at last condensation reaction between the product of the second step and pentaerythritol triacrylate (PETA). Different triols, with molecular weight ranged from 400 to 1000, were prepared by controlling reactant molar ratio, reaction temperature and initiator concentration. The probable structures of the final products were analyzed and it was observed that one product preceded the ring-opening reaction just at on one side of THEIC, while others proceeded on all sides of THEIC. In the cured film properties tests it was examined that the multi-functional polyurethane acrylates exhibited very fast-curing and high hardness as compared with the commercial six functional PUA. Jian et al. (2009) synthesized dual-cure polyurethane acrylates (PUA) with different double bonds content by using aliphatic polyisocyanate and 2-hydroxyethyl acrylate (HEA). From the results of infra red (IR) and nuclear magnetic resonance (NMR) spectra, it could be concluded that the C=C content of the polyurethane was controlled by adding different amounts of HEA. Three different formulations were achieved by mixing synthesized oligomer and epoxy acrylate. It was found that by only UV exposure, the pendulum hardness, methylethyl ketone (MEK) resistance and glass transition temperature (Tg) were increased, however the flexibility was reduced with the increase of double bond content. The pendulum hardness and MEK resistance were improved, after heat treatment; also, flexibility and Tg were even better. The results presented that in the partially UV cured system, the presence of NCO groups had effects on the mechanical and thermal properties of the film after heating treatment; more crosslinking network could be produced in dual-cure system through heat curing. Naghash and Abili (2010) synthesized a new silicone containing allylic monomer, allyl 3- (triethoxysilyl) propyl carbamate (ATESPC), based on (3-isocyanatopropyl) triethoxysilane (ICPTES) and allyl alcohol (AAL). Then water-borne polyurethane (WPU) was formulated by it. After that a series of new siliconized WPU, vinyl acetate (VAc)/2-ethylhexylacrylate (2-EHA) and ATESPC hybrid latexes P(VAc-2-EHA)/PU/Si was synthesized successfully by the emulsion copolymerization in the presence of a WPU dispersion. The WPU dispersion was synthesized by a poly addition reaction of hexamethylene diisocyanate (HMDI) with polypropylene glycol (PPG-1000) and dimethylol propionic acid (DMPA) as chain extender. The NCO chain ends of polyurethane prepolymer were reacted with water, which act as a further chain extender. Films were prepared and characterized for different hybrid latexes of diverse compositions. It was 24 found that ATESPC had prepared successfully as a new monomer with double bond of allylic, two functional groups, and carbamate linkage. Results showed that ATESPC segments were present in the structures of monomer and copolymer. P(VAc-2-EHA)/PU/Si improved the water resistance of PU latex. The presence of ATESPC in the P(VAc-2-EHA)/PU copolymer resulted an increase in the heat stability. The rate of reaction was decreased by increasing ATESPC. Wang et al. (2010) prepared a multi-functional water-borne polyurethane acrylate (WPUA) nanocomposite coating by introducing the acrylate groups at the end of the polyurethane main chains and then modified by antimony doped tin oxide (ATO) nanoparticles by ultrasonic dispersion. Morphological and structural features of coatings were evaluated by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and a 3D measuring laser microscope. Performance of the coatings was assessed by water resistance studies, thermo gravimetric analysis (TGA), dynamic mechanical thermal analysis (DMTA) and mechanical tests such as tensile strength and elongation at break. The results showed that the WPUA/ATO coatings obsessed good thermal and mechanical properties. The UV–visible–near infrared (UV–VIS–NIR) spectra suggested that the PUA/ATO coatings could absorb near infrared (NIR) radiation that’s why it would prevent heat transmission and heat diffusion effectively. Zhang et al. (2010) synthesized a series of ultraviolet (UV) curable water-borne polyurethane- acrylate (WPUA) with different average functionalities in new methods. The chemical route of this synthesis was traced by Fourier-transform infrared spectroscopy (FT-IR) and the effect of average functionality on properties of WPUA was also systemically examined. It was observed that the average functionality had a positive effect on the water resistance and tensile strength of WPUA, while the increase of average functionality decreased the extension and viscosity of WPUA samples. Moreover, through the investigation on the UV curing kinetics, it was established that the too low or too high average functionality was unfavorable for the increase of unsaturation conversion. It was possible to observe by WAXD pattern that the orderly phase was present in WPUAs and it was hardly affected by the average functionality. By this study it was suggested that WPUA can be utilized to improve the mechanical features and increase the solid contents of the products in the industrial applications.

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Chapter 3

26

3 Materials and Methods

The PUA copolymers were synthesized by using different monomers in various combinations and proportions. Also, different intermediates and final products in this research work were characterized by appropriate sophisticated techniques.

3.1 Chemicals

3.1.1 Monomers

3.1.1.1 Isocyanates

 1-Isocyanato-3-Isocyanatomethyl-3,5,5-Trimethylcyclohexane (IPDI)

This cyclic aliphatic isocyanate, IPDI is also named as isophorone diisocyanate. It was purchased from Sigma Aldrich Chemical supplier. This transparent liquid has molecular formula,

C12H18N2O2 and molecular weight, 222.29 g/mol. Its chemical structure is given below in Figure 3.1.

Figure 3.1 Chemical structure of isophorone diisocyanate (IPDI)  2,4/2,6-diisocyanato-1-methyl-benzene (TDI)

An aromatic isocyanate, TDI is also called as toluene diisocyanate or methyl phenyl diisocyanate. The TDI was purchased as 80/20 mixture of the 2,4 and 2,6 isomers, respectively from Fluka Chemical suppliers. It was like a transparent liquid. Its molecular formula and molar mass are C9H6N2O2 and 174.2 g/mol, respectively. The chemical presentation of its structure is as shown in Figure 3.2. 27

Figure 3.2 Chemical structure of Toluene diisocyanate (TDI)  Methylene bis (4-cyclohexylisocyanate) (H12MDI)

The cyclic aliphatic isocyanate, H12MDI with molecular weight 262.35 g/mol and molecular formula C15H22N2O2 was purchased from Sigma Aldrich Chemical suppliers. It was transparent liquid, as 90 % mixture of isomers. Its chemical structure is shown in Figure 3.3.

Figure 3.3 Chemical structure of Methylene bis (4-cyclohexylisocyanate) (H12MDI)

3.1.1.2 Polyols

 Poly (2-methyl-1,3-propylene glutarate) (PMPGlu), diol terminated

A polyester polyol, Poly (2-methyl-1,3-propylene glutarate), diol terminated (Mw 1020 g/mol ) was purchased from Sigma Aldrich Chemicals suppliers. It was transparent viscous liquid. It chemical structure is given in Figure 3.4.

Figure 3.4 Chemical structure of Poly (2-methyl-1,3-propylene glutarate) (PMPGlu), diol terminated 28

 Polycaprolactone polyol (CAPA2100)

Another polyester polyol, Polycaprolactone, CAPA2100, with molecular weight 1000 g/mol was received from perstorp UK limited. It was recieved in the form of white waxy solid. The Figure 3.5 illustrates the chemical structure of CAPA2100.

Figure 3.5 Chemical structure of Polycaprolactone, CAPA2100  Poly (oxyethylene) (PEG)

A polyether polyol, PEG with common name polyethylene glycol polyol was also used in synthesis of PUA copolymers. It was received from Sigma Aldrich Chemical supplier as a white solid. To remove expected water vapours PEG was dried in vacuum oven for approx. 12 hrs. Its chemical structure can be seen in Figure 3.6.

Figure 3.6 Chemical structure of Poly (oxyethylene) (PEG)

3.1.1.3 Acylates

 2-Hydroxyethyl acrylate (2-HEA)

Monoester with ethylene glycol, 2-HEA was purchased from Sigma Aldrich Chemical suppliers as a transparent liquid. Its chemical formula and molecular weight are C5H8O3 and 116.12 g/mol, respectively. The chemical structure of 2-HEA is given in Figure 3.7.

29

Figure 3.7 Chemical structure of 2-Hydroxyethyl acrylate (2-HEA)  2-Hydroxyethyl methacrylate (2-HEMA)

The 2-HEMA was received as a clear liquid from Sigma Aldrich Chemical suppliers. Its molecular weight is 130.14 g/mol. The simple chemical formula is C6H10O3 and structural formula is given in Figure 3.8.

Figure 3.8 Chemical structure of 2-Hydroxyethyl methacrylate (2-HEMA)  n-Butyl acrylate (BA)

The n-Butyl acrylate 99 % pure was purchased from Sigma Aldrich Chemical suppliers. It was a clear liquid with strong esteric smell. Its molecular weight and chemical formula are 128.17 g/mol and C7H12O2, respectively, while structural formula is shown in Figure 3.9.

Figure 3.9 Chemical structure of n-Butyl acrylate (BA)

3.1.2 Emulsifiers

3.1.2.1 Neutral emulsifier

30

Polyethylene glycol sorbitan monostearate (Tween 60) having molecular formula

C24H46O6(C2H4O)n was purchased from local market traders. It is a neutral saturated emulsifier; it is important to mention here that it cannot interfere chemically during vinyl polymerization as it can be expected from an unsaturated one. Also, sorbiton monolaureate (sorbiton monododecanate; C18H34O6, Fw = 346.47) supplied by Sigma Aldrich was used to wash the substrate fabric.

3.1.2.2 Anionic emulsifier

The sodium salt of alkyl aryl polyglycol ether sulphate with 100 % active content was purchased from local market.

3.1.3 Non-surfactant stabilizer

Some non-surfactant stabilizers like water soluble polymers can promote emulsion polymerization even though they do not typically form micelles and do not act as surfactants. It is believed that these polymers graft onto growing polymer particles and stabilize them. In this study polyvinyl alcohol (PVA, 87-89 % hydrolyzed with molecular weight 13000-23000, from Sigma Aldrich Chemical Co.) was used as stabilizer.

3.1.4 Initiator

For the generation of free radicals during polymerization ammonium persulphate (APS,

(NH4)2S2O8) was used as water soluble initiator along with few crystals of sodium thiosulphate

(Na2S2O3.5H2O).

3.1.5 Solvents

Different aqueous and non aqueous solvents were used during the course of synthesis. Main solvent during copolymerization was deionized and distilled water. However, Toluene (dried with sodium metal), dry N,N-dimethylformamide (DMF), acetone and chloroform were also used during characterization steps.

31

3.2 Methodology

Polyurethane acrylate copolymers were synthesized by following three step synthesis processes. Active PUs with free NCO terminals were synthesized by prepolymer method. These active PUs were reacted with some hydroxy acrylate and converted into resins with vinyl terminals. At the final pace these vinyl terminated resins were copolymerized by free radical process with butyl acrylate.

3.2.1 Synthesis of PU prepolymers:

The synthesis of PU prepolymers was carried out according a recommended procedure (Barikani and Hepburn, 1986). The chemistry of this reaction is given in Figure 3.10. For this purpose diisocyanate and polyol were basic monomers.

Figure 3.10 Synthesis of PU prepolymer by the reaction of OH groups of polyol with NCO groups of isocyanate The catalyst (DBTDL) was used some time when isocyanates were aliphatic in nature, but there was no need to use it in presence of aromatic ones. The stichiometric amounts of polyol (2 moles) and isocyanate (3 moles) were charged into a 500 mL four-necked round bottom glass reactor equipped with a mechanical stirrer, a thermometer, a reflux condenser, heating oil bath and a nitrogen gas inlet system. The temperature of the oil bath was increased upto 60 oC. This

32 mixture of Polyol and isocyanate was stirred continuously under the blanket of nitrogen gas and temperature was increased steadily from 60 oC to 90 oC. It took approx. 2.0 hrs to obtain NCO terminated PU prepolymer. After that temperature of the reaction vessel was decreased back to 60 oC.

3.2.2 Introduction of unsaturation at the ends of PU prepolymers:

In second step of synthesis unsaturations were introduced at the ends of PU prepolymers. It was possible by the reaction of PU prepolymers having free NCO groups with different hydroxy acrylates. In this reaction, active groups were free isocyanate groups of PU prepolymers and hydroxyl groups of hydroxy acrylates. These functional groups reacted to generate urethane linkages as shown in Figure 3.11.

Figure 3.11 Introduction of unsaturation at the ends of PU prepolymer by the reaction of NCO terminated PU prepolymer with OH groups of hydroxy acrylate

33

Hence, because of acrylates unsaturated prepolymers or vinyl terminated PU resins were produced (Wang et al. 2008). The stochiometric amount of hydroxy acrylate monomer (2 moles) was added to PU prepolymer at lower temperature approx. 50 oC to 60 oC, to avoid any possibility of thermal cross linking of unsaturated sites in the system. After addition of hydroxyl acrylate, reaction was carried out without any further change in temperature with constant stirring for approx. 1.0 hr. There was a noticeable change in viscosity of the reaction mixture during this course of reaction. The PU prepolymer was viscous transparent, with just addition of hydroxyl acrylate its viscosity decreased sharply. But again viscosity of reaction mixture started to increase after few minutes of this addition. So, at the end of reaction a thick, viscous and transparent material was saved in sample bottles for further use. Sometime black bottles were used for saving of this vinyl terminated PU resins to avoid any possible photoreaction.

3.2.3 Copolymerization of PU resin with butyl acrylate (BA) At the last pace, copolymerization of vinyl terminated PU resin with butyl acrylate (BA) was carried out through emulsion polymerization process as given in Figure 3.12. This process was performed in the presence of polyvinyl alcohol (PVA), anionic or neutral emulsifier and ammonium persulphate (APS) with Na2S2O3 (as redox initiator). Deionized water was used as solvent throughout the emulsion process. Aqueous solutions of PVA 3 % w/v and emulsifier 6 % v/v were prepared separately, and then they were introduced into the reaction flask with 10 mL of 0.2 % w/v initiator solution slowly. This addition was completed in almost 3.5 hrs. with continuous stirring at 55 oC to 60 oC. Basic formulations to prepare PUA copolymers are given in Table 3.1 and 3.2, respectively. Table 3.1 Basic ingredients for synthesis of PUA copolymer emulsions Sr. no. Ingredients Amount (%)

1 Deionized H2O 66-75 2 APS 0.02

3 Na2S2O3.5H2O 0.01 4 Emulsifier 12 5 PVA 3 6 BA 18-10 7 PU rersin 10-50 of BA 34

O O O O

R R R O N N O n O N N O H H H H O O R' C CH2 H2C C R' O Vinyl terminated PU prepolymer O

H2C R CH2 O

H2C C4H9 O Butyl acrylate (BA)

BA BA

R

BA BA

PUA copolymer

Figure 3.12 Copolymerization of vinyl terminated PU prepolymer with butyl acrylate (BA) In each set of the emulsions, amount of BA and vinyl terminated PU resin was assorted progressively. White milky emulsions were obtained at the end of reaction, which were saved for further investigations.

Table 3.2 Formulation for synthesis of PUA copolymer emulsions Emulsion no. PU resin composition PU/BA (% ) 1.1 10/90 1.2 20/80 1.3 diisocyanate/polyol/hydroxy acrylate 30/70 1.4 40/60 1.5 50/50

35

3.3 Characterization

3.3.1 Fourier transform infra red spectroscopy (FT-IR)

For chemical characterization FT-IR was used as a key technique to verify the path of synthesis. The related spectra were collected for all of the monomers and at every stage of synthesis process by Bruker Equinox 55 (Germany) and Shimadzu IR Prestige-21 spectrophotometers. The scanning region was 4000 cm-1 to 500 cm-1. Samples were analyzed by applying on KBr/NaCl discs or with the help of KBr powder.

3.3.2 Differential scanning calorimetry (DSC)

Thermal behavior of PUA copolymers was studied by using differential scanning calorimeter (DSC) Q-200, TA instruments, England and NETSCH DSC 200 F3 Germany, instruments. A small amount in few mgs of the dried copolymers was placed in standard aluminium pans with pierced lid. The DSC analysis was carried out from temperature range -60oC to 250oC with heating rate of 10 oC. Cooling accessory used to attain low temperature was refrigerator cooling system (RCS 40) in DSC Q-200.

3.3.3 Thermogravimetric analysis (TGA)

Thermal decomposition (thermogravimetric analysis) study was carried out by using TGA-PL, England and SDT Q-600, TA instruments, England, instruments. TGA was performed in platinum pan with a neutral environment under the flow rate of 50 mL/min of nitrogen gas. Temperature scan was carried out from ambient temperature (25 oC) to 600 oC with the ramp of 10 oC. Weight loss of sample in percent (%) was recorded versus change in temperature (oC).

3.3.4 Dynamic light scattering (DLS)

Particle size and polydispersity index (PDI) of PUA copolymer emulsions were measured using SEMATech Laboratory, SEM 633 light scattering apparatus, France. In this light scattering

36 apparatus Helium Neon laser lamp was the source of light with wavelength 632.8 nm. The average frequency of light was 363.62 KHz.

3.3.5 Viscosity of PUA emulsions

Viscosity of PUA emulsions was measured by Brookfield DV-II + Pro viscometer using UL adapter spindle. The average temperature and shear rate were 25 oC and 20 rpm, respectively. It was a digital viscometer, spindle rotated in emulsion sample and viscosity appeared on the screen readily.

3.3.6 Dry weight contents (%)

Dry weight contents or solid contents of PUA emulsions were determined by gravimetric method. It was performed by placing a weighed amount of emulsions in aluminum cups at 50 oC to 60 oC in oven for 24-48 hours. These samples were weighed till a constant weight. The dry weight contents were calculated according to following formula

% dry weight = Wb/Wa * 100

Where Wa is weight of sample before drying and Wb is weight after drying.

3.3.7 Chemical and water resistance

Qualitatively chemical and water resistance was evaluated according to ASTM D 1647-89. Glass panels coated with PUA emulsions were allowed to dry for three consecutive days at room temperature. The periphery of panels was covered with wax in order to restrain the migration of chemical solutions under the films from open ends. 3 % (w/w) solutions of H2SO4 and NaOH were used for chemical resistance and changes in appearance of films were monitored after three days with naked eye. Also, for water aluminum panels coated with PUA emulsions were allowed to dry for two days. Dried panels were immersed in deionized water at room temperature. After 18 hours panels were removed from water, wiped carefully and dried at room temperature to monitor any change. 37

3.3.8 Pre-treatment of fabric substrate

Mill desized, scoured, bleached, plain, 100 % cotton combed satin fabrics; satin striped weave was supplied by textiles Mills in Faisalabad, Pakistan. The characteristics i.e., quality of the fabric, construction, count, blend ratio etc., are presented in Table 3.3. Before application of the polyurethane acrylate copolymers, the fabric was further cleaned in the laboratory by washing at o 100 C for 60 minutes using a solution containing 2g/L, Na2CO3 and 1 g/L, sorbiton monolaureate a non-ionic surfactant. The fabric was then washed several times with hot water then with cold water and finally dried at ambient conditions.

Table 3.3 Specifications of fabric substrate Blend Ratio Quality Sr. no. Cotton/Polyester Construction/count Weave

Plain stripe satin/cotton 100 % combed 01 (Satin stripe = 1cm) cotton (30 x 30/140 x 80) 4/1

3.3.9 Textile Performance

All of the PUA emulsions were applied on textile fabric and their textile performance was evaluated accordingly. The fabric was characterized according to ASTM D-3775. Other quality parameters like washing fastness, rubbing fastness, light fastness, abrasion resistance, pilling and tear strength were assessed according to AATCC 61-2003, 8-2005, 16-2004, ASTM D-4966, ASTM D-3514-02 and ASTM D-1424 / BS EN ISO 13937-2, respectively.

38

Chapter 4

39

4 Results and Discussion

The main aim of this project was to synthesize and characterize the polyurethane acrylate copolymers containing different diisocyanates and polyols in different proportions with butyl acrylate. Therefore, synthesis of a series of PUA copolymers was carried out, following the synthetic route outlined in section 3.2. The reaction of one equivalent of polyol with three equivalents of isocyanate led to –NCO terminated PU prepolymer (3.2.1) which was further extended with 2 equivalents of hydroxy acrylate in order to incorporate unsaturations at the free ends of PU chains (3.2.2). The last step was copolymerization of vinyl terminated PU prepolymer with BA through emulsion polymerization (3.2.3). The whole work was completed in two parts of study; part I and II. The part I was performed at Iran Polymer and Petrochemical Institute, Tehran, while the part II was carried out at Physical Chemistry Laboratory, Department of Chemistry and Biochemistry, University of Agriculture, Faisalabad, Pakistan.

Part I

In this part of study different series of PUA copolymers were synthesized and characterized accordingly. The chemical composition was varied i.e. different monomers in various ratios were tried and their structure property correlations were studied.

4.1 Chemical characterization of PUA copolymer emulsions

All copolymers synthesized in this project were characterized for their molecular structure by FT-IR spectroscopy. This technique was used as a key tool to monitor the every step of synthetic pathway. The molecular characterization of all different series of PUA copolymers is presented here with respective FT-IR spectral details.

4.1.1 Chemical characterization of AL-1-PEG copolymer series

The AL-1-PEG copolymer series was synthesized by utilizing H12MDI, PEG, 2-HEMA and

40 n-BA monomers. Basic formulation and composition is given below in Table 4.1. Table 4.1 Labeling, composition and PU/BA ratio for the different PUA emulsions in AL- 1-PEG copolymer series Sr. No. Sample code PU resin composition PU/BA (% )

1. AL-1.1-PEG H12MDI/PEG/HEMA 10/90

2. AL-1.2-PEG H12MDI/PEG/HEMA 20/80

3. AL-1.3-PEG H12MDI/PEG/HEMA 30/70

4. AL-1.4-PEG H12MDI/PEG/HEMA 40/60

5. AL-1.5-PEG H12MDI/PEG/HEMA 50/50

The FT-IR spectra of all the monomers, intermediates and final products involved in preparation of AL-1-PEG copolymer series are arranged in Figure 4.1. The IR spectral analysis was mainly used to evaluate and confirm the completion of PUA copolymerization reaction in terms of disappearance of the isocyanate –NCO peak at 2260 cm-1 to 2270 cm-1 and the appearance of – NH peak at 3000 cm-1 to 3400 cm-1. (Athawale and Kulkarni, 2009) relied on these two confirmation signals during preparation of urethane acrylate composites by emulsion polymerization technique. The interpretations in present study are in accordance with these reported observations.

The FT-IR spectrum of H12MDI (Fig. 4.1 a) exhibited a strong characteristic stretching vibration -1 band of –NCO at 2259 cm . The other prominent peaks in functional group region of H12MDI spectrum (Figure 4.1 a) were asymmetric and symmetric stretching vibration peaks of CH2 at 2929 cm-1 and 2853 cm-1, respectively. In the lower frequency region (Fig. 4.1 a) a strong narrow peak at 1449 cm-1 (bending vibration of aliphatic CH) and comparatively less intense peak at -1 1151 cm (twisting vibration of CH in CH2) were also observed. Wu et al. (2001) assigned -1 -1 asymmetric and symmetric stretching vibration peaks of CH2 at 2955 cm and 2876 cm , respectively during structural and composition study of the urethane acrylic composite latex films, accordingly these were also observed in Figure 4.1 a. Xu and Shi (2005) observed bending -1 vibration of aliphatic CH groups at 1454 cm and twisting vibration of CH in CH2 groups at 1180 cm-1 in FT-IR analysis of hyper-branched polyurethane acrylates. The FT-IR spectral peaks of PEG (Fig. 4.1 b) were assigned as follows: 3475 cm-1 (OH -1 -1 stretching vibration); 2877 cm (CH2 stretching vibration); 1466 cm (bending vibration of CH -1 -1 in CH2 groups); 1356 cm (parallel vibration of CH in CH2); 1279 cm (asymmetric stretching 41 vibration of C-O-C ether groups); 1113 cm-1 (symmetric stretching vibration of C-O-C ether groups). Before this, Wang et al. (2010) and Zhang et al. (2010) have reported stretching vibration of C-O-C in ether linkages at 1110 cm-1 as it was observed here in Figure 4.1 b. Also, unavailability of C=O stretching peak was a strong verification for ether based structure of soft segment (PEG). Because of bending and parallel vibrations of CH in aliphatic CH2 groups, peaks at 1454 cm-1 and 1380 cm-1, respectively were observed by (Xu and Shi, 2005) during synthesis and characterization of hyper-branched polyurethane acrylates.

At the first step of synthesis of PUA copolymer, H12MDI and PEG were reacted and –NCO terminated PU prepolymer was generated. The FT-IR spectrum of –NCO terminated PU prepolymer (Fig. 4.1 c) presented a visible change. The signal for the OH groups of PEG (Fig. 4.1 b) disappeared and intensity of isocyanate (–NCO) groups (Fig. 4.1 a) reduced to some extent. It showed that OH groups of soft segment (PEG) have reacted with isocyanate (–NCO) groups of H12MDI producing urethane linkages. A new peak for –NH units of urethane linkages appeared at 3328 cm-1, supporting this particular reaction. An intense peak of newly synthesized C=O groups of urethane linkages at 1719 cm-1 was also observed in this spectrum that is an additional powerful evidence for synthesis of urethane linkages at this step. The disappearance of intense peak (compare 4.1 a and c) at 2259 cm-1 (–NCO) and appearance of less intense peak at 2264 cm-1 (–NCO) indicated that the –NCO groups have reacted with OH groups of PEG but not completely, which established the fact for synthesis of PU prepolymer with free isocyanate terminals. In the FT-IR spectrum of NCO terminated PU prepolymer other peaks were accredited -1 -1 -1 as: 2921 cm (CH stretching of CH2); 2264 cm (–NCO group); 1527 cm (stretching vibration of –CONH in urethane linkages); 1450 cm-1 (–CNH bending vibration). Similar results have already reported for –NCO terminated PU prepolymer at the first step of synthesis of UV-curable polyurethane acrylate films, where the intensity of –NCO peak at 2270 cm-1 were reduced in FT- IR spectrum of PU prepolymers (Wang et al., 2008). Lu and Larock (2007) synthesizing hybrid latexes from water-borne polyurethane and acrylics by emulsion polymerization, –CONH stretching peak at 1536 cm-1 was noticed as it was observed here in FT-IR spectrum of –NCO terminated PU prepolymer (Figure 4.1 c). The free isocyanate groups of PU prepolymers were further reacted with 2-hydroxy ethyl methacrylates (2-HEMA) (Wang et al., 2008).

42

Figure 4.1 FT-IR spectra of AL-1-PEG copolymer series, a. H12MDI, b. PEG, c. PU prepolymer with free NCO groups, d. 2-HEMA, e. vinyl terminated PU prepolymer, f. BA, g. PUA copolymer

43

The observed peaks in the FT-IR spectrum of 2-HEMA (Fig. 4.1 d) were assigned as: 3438 cm-1 -1 -1 (OH stretching vibration); 2957 cm (asymmetric CH2 stretching); 2917 cm (symmetric CH2 stretching); 1714 cm-1 (C=O stretching of α, β unsaturated carbonyl group); 1635 cm-1 (C=C -1 -1 stretching); 1454 cm (bending vibration of =CH2); 1378 cm (symmetric bending vibration of -1 -1 CH3 and CH2); 1298 cm and 1170 cm (stretching vibrations of C–O in linkages). The assignment of the peaks (Fig. 4.1 d) is in agreement with other researchers. Wang et al. (2010) working on water-borne polyurethane acrylate nanocomposite coatings, attributed peaks at 1638 -1 -1 cm and 1412 cm to C=C stretching vibrations and vibrations of =CH2 groups, respectively. While Xu and Shi (2005) reported asymmetric stretching vibration and symmetric stretching vibration of C-O in ester groups at 1230 cm-1 and 1060 cm-1, respectively. Normally two or more bands are expected for ester linkages at 1300-1000 cm-1 (Zhang and Zhang, 2004). After the reaction of –NCO terminated PU prepolymer (Fig. 4.1 c) with 2-HEMA (Fig. 4.1 d), the vinyl terminated PU polymer was produced. The FT-IR spectra of vinyl terminated PU polymer (Fig. 4.1 e) showed intense stretching at 3333 cm-1 (–NH stretching) due to further formation of urethane linkages. The asymmetric and symmetric CH stretching peaks of CH2 groups were observed at 2919 cm-1 and 2891 cm-1, respectively. The FT-IR spectrum also demonstrated sharp peaks at 1716 cm-1 (C=O stretching vibration) and 1636 cm-1 (C=C stretching) in functional group region as also noticed by Zhang et al. (2010). The vinyl terminated PU prepolymer spectrum pointed out that –NCO peak has disappeared completely confirming the complete utilization of the –NCO end groups with OH groups of 2-HEMA, generating vinyl terminated PU prepolymer. Moreover, a peak at 810 cm-1 (out of plane bending -1 of CH in =CH2) along with peak at 1638 cm (C=C stretching vibration) supported strongly for inclusion of 2-HEMA in the PU backbone. According to previous reports, aamalgamation of -1 acrylates into PU backbone gives a peak at 810 cm for bending of CH in =CH2 (Jian et al., -1 -1 2009). Appearance of peaks at 810 cm (bending of CH in =CH2), at 1635 cm (C=C stretching vibration) and disappearance of diisocyanate peak at 2264 cm-1 were considered as a signal, for the completion of reaction between acrylates and –NCO terminated PU prepolymer (Wang et al., 2008). The vinyl terminated PU prepolymer chains were further extended with the addition of BA at the last step of synthesis. The observed peaks in the FT-IR spectrum of BA (Fig. 4.1 f) were ascribed -1 -1 -1 as: 2960 cm , 2950 cm and 2874 cm (stretching vibrations of aliphatic CH in CH2 and CH3 ); 44

-1 -1 -1 -1 1727 cm (C=O stretching); 1637 cm (C=C stretching); 1466 cm (CH2 bending); 1274 cm , 1192 cm-1 and 1065 cm-1 ( stretching vibrations of C-O in ester groups); 1408 cm-1 and 811 cm-1 (characteristic bands of acrylates). (Xu and Shi, 2005) ascribed peaks at 3000-2865 cm-1 to stretching vibrations of aliphatic saturated –CH groups, while characteristic bands of acrylates were noticed at 1408 cm-1 and 811 cm-1 in the FT-IR spectrum of UV-curable organic–inorganic hybrid urethane acrylates by Xu et al. (2006). Zhang and Zhang (2004) attempting for γ-ray initiated seeded emulsion polymerization of methyl methacrylate in the presence of water-borne polyurethanes reported appearance of three adjacent peaks in the region 1145–1240 cm-1 due to OC–O–C stretching vibrations in ester linkages. Therefore, we consider that the FT-IR spectrum in Figure 4.1 f represents the chemical structure of BA. To present comprehensive information about the vibrational mode changes due to copolymerization of BA with the polyurethane containing unsaturated ends, FT-IR spectrum of the final copolymer was obtained (Fig. 4.1 g). This spectrum confirmed the completion of the synthesis of PU acrylate copolymer. In functional group region of this spectrum there were characteristic peaks at 3369 cm-1 (stretching vibration of –NH groups in urethane linkages), 2959 -1 -1 -1 cm and 2872 cm (stretching vibrations of aliphatic CH in CH2 and CH3 groups), 1734 cm (stretching vibration of C=O groups). Absence of C=C peak for stretching vibrations at about 1640 cm-1, confirmed that all of the unsaturation sites were utilized in vinyl polymerization of BA with vinyl terminated PU prepolymer. Other peaks in FT-IR spectrum of PUA copolymer (Fig. 4.1 g) were accredited as: 1453 cm-1 (–CNH bending vibration); 1249 cm-1and 1163 cm-1 (C-O stretching vibrations of ester linkages in acrylates); 1114 cm-1 (C-O-C stretching vibration -1 of ether linkages); 841 cm ( stretching vibration of –OC4H9 in ester linkages). Wu et al. (2001) and Lu and Larock (2007) working independently on polyurethane acrylates have experienced a -1 peak at 841 cm for –OC4H9 as reported here in Figure 4.1 g. Hence it is concluded that during this FT-IR spectral analysis of AL-1-PEG copolymer series, the disappearance of the –NCO and C=C peaks and the appearance of –NH peak confirmed the completion of copolymerization reaction through different steps. Moreover, the clear peaks at -1 -1 -1 1453 cm , 1114 cm and 841 cm for –CNH, C–O–C and –OC4H9 in FT-IR spectrum of PUA copolymer (Fig. 4.1 g) respectively provided additional confirmation for synthesis of PUA copolymer. Therefore, the FT-IR spectrum of the final product (Fig. 4.1 g) supported the

45 proposed structure of the final copolymer. The whole spectral analysis implied that the reaction was carried out step wise and a pre-designed PUA copolymer was synthesized effectively.

4.1.2 Chemical characterization of AL-1-PCL copolymer series

The AL-1-PCL series of PUA copolymer was synthesized using H12MDI, PCL, 2-HEMA and BA as monomers. The PU resin composition and PU/BA (%) used in this synthesis is presented in Table 4.2. The FT-IR spectra of all of the monomers, intermediates and final products are presented in Figure 4.2. Table 4.2 Labeling, composition and PU/BA ratio for the different PUA emulsions in AL-1- PCL copolymer series Sr. No. Sample no. PU resin composition PU/BA (% )

1. AL-1.1-PCL H12MDI/PCL/HEMA 10/90

2. AL-1.2-PCL H12MDI/PCL/HEMA 20/80

3. AL-1.3-PCL H12MDI/PCL/HEMA 30/70

4. AL-1.4-PCL H12MDI/PCL/HEMA 40/60

5. AL-1.5-PCL H12MDI/PCL/HEMA 50/50

The FT-IR spectrum of H12MDI (Fig. 4.2 a) has well explained already in section 4.1.1. The FT- IR spectral peaks of PCL (Fig. 4.2 b) were assigned as follows: 3439 cm-1 (OH stretching -1 -1 vibration); 2942 cm (asymmetric CH2 stretching vibration); 2864 cm (symmetric CH2 stretching vibration); 1724 cm-1 (C=O stretching vibration). Previously, Wang et al. (2008) assigned broad peak at 3400-3500 cm-1 to OH groups of soft segment and at 1727 cm-1 to C=O groups in structural study of polyurethane acrylate films by FT-IR technique.

By the reaction of –NCO groups of H12MDI with OH groups of PCL, –NCO terminated PU prepolymer was generated at the first step of synthesis. The FT-IR spectrum of –NCO terminated PU prepolymer (Fig. 4.2 c) indicated a noticeable change i.e. signal for the OH groups of PCL (Fig. 4.2 b) completely disappeared and intensity of isocyanate (–NCO) groups (Fig. 4.2 a) was reduced to some extent. These changes suggested that OH groups of soft segment PCL totally reacted with isocyanate (–NCO) groups of H12MDI and a signal for newly synthesized –NH units appeared at 3374 cm-1 with increased intensity of C=O stretching peak at 1733cm-1 confirming 46 the synthesis of PU prepolymer. The disappearance of intense peak (compare 4.2 a and c) at 2259 cm-1 (–NCO) and appearance of less intense peak at 2263 cm-1 (–NCO) indicated that the – NCO group reacted with OH groups of PCL but not completely, which established the evidence for the synthesis of isocyanate terminated PU prepolymer. Other peaks observed in the FT-IR spectrum of NCO terminated PU prepolymer were assigned as: 2932 cm-1 (CH asymmetric -1 -1 stretching of CH2); 2859 cm (CH symmetric stretching of CH2); 2263 cm (–NCO group); 1521 cm-1 (–CONH stretching); 1453 cm-1 (–CNH bending vibration). Similar results have reported by Wang et al. (2008) for –NCO terminated PU prepolymer at the first step of synthesis of UV-curable polyurethane acrylate films, where the intensity of –NCO peak at 2270 cm-1 were reduced in FT-IR spectrum of PU prepolymers. During FT-IR spectral analysis of PU and PUA latex films –CONH stretching at 1550 cm-1 was observed by Wu et al. (2001). The free isocyanate groups of PU prepolymers were further reacted with 2-hydroxy ethyl methacrylates (2-HEMA) (Wang et al., 2008). The observed peaks in the FT-IR spectrum of 2- HEMA (Fig. 4.2 d) have explained in section 4.1.1. After the reaction of –NCO terminated PU prepolymer (Fig. 4.2 c) with 2-HEMA (Fig. 4.2 d), the vinyl terminated PU polymer was produced. FT-IR spectrum of vinyl terminated PU polymer (Fig. 4.2 e) showed an intense stretching at 3374 cm-1 (–NH stretching) due to formation of additional urethane linkages in the vinyl terminated PU prepolymer. The asymmetric and -1 -1 symmetric CH stretching peaks of CH2 groups were observed at 2929 cm and 2859 cm , respectively. The FT-IR spectrum also showed sharp peaks at 1729 cm-1 (C=O stretching vibration) and 1638 cm-1 (C=C stretching) in functional group region as also noticed by Zhang et al. (2010). The vinyl terminated PU prepolymer spectrum indicated that –NCO peak has disappeared completely confirming the complete utilization of the –NCO groups with OH groups of 2-HEMA, generating vinyl terminated PU prepolymer. Additionally, a peak at 816 cm-1 (out -1 of plane bending of CH in =CH2) along with a peak at 1638 cm (C=C stretching vibration) gave a strong evidence for the incorporation of 2-HEMA in the PU backbone. The addition of 2- -1 HEMA into PU backbone generated a peak at 810 cm for bending of CH in =CH2 (Jian et al., -1 -1 2009). Peaks at 810 cm (bending of CH in =CH2) and at 1635 cm (C=C stretching vibration) were considered as a signal for the completion of reaction between hydroxy group of acrylate and –NCO terminated PU prepolymer (Wang et al., 2008).

47

At the last step of copolymerization, the vinyl terminated PU prepolymer chains were further extended with the addition of BA. The FT-IR spectrum of BA (Fig. 4.2 f) have described in section 4.1.1 already. To provide comprehensive information about the vibrational mode changes due to the copolymerization of BA to the polyurethane containing unsaturated ends, FT-IR spectrum was obtained from the final copolymer Figure 4.2 g. This spectrum confirmed the formation of PU acrylate copolymer. In functional group region of this spectrum there were characteristic peaks at 3349 cm-1 (stretching vibration of –NH groups in urethane linkages), 2958 cm-1 and 2873 cm- 1 -1 (stretching vibrations of aliphatic CH in CH2 and CH3 groups), 1734 cm (stretching vibration of C=O groups). Absence of C=C peak for stretching vibrations at about 1640 cm-1, confirmed that all of the unsaturated sites were utilized in vinyl polymerization of BA with vinyl terminated PU prepolymer. The other peaks in FT-IR spectrum of PUA copolymer (Fig. 4.2 g) were accredited as: 1511 cm-1 (–CONH bending vibration); 1453 cm-1 (bending vibration of aliphatic -1 -1 -1 CH in CH2 and CH3 groups); 1248 cm , 1162 cm and 1116 cm (C-O stretching vibration of -1 -1 ester linkages); 842 cm ( stretching vibration of –OC4H9 in ester linkages). A peak at 1550 cm -1 due to –CONH groups and another peak at 841 cm owing to stretching vibrations of –OC4H9 in ester linkages were assigned in the synthesis of urethane acrylic composite latex films from IPDI and different acrylates (Wu et al., 2001). A series of new water-borne polyurethane acrylic hybrid latexes successfully synthesized by the emulsion polymerization of acrylic monomers (butyl acrylate and methyl methacrylate) in the presence of a soybean oil-based water-borne PU dispersion using potassium persulfate as an initiator (Lu and Larock, 2007). They also have -1 -1 experienced two peaks at 1536 cm and 841 cm for –CONH and –OC4H9, respectively as reported in Figure 4.2 g. It could be concluded that during this FT-IR spectral analysis of AL-1-PCL copolymer series, the disappearance of the –NCO and C=C peaks and the appearance of –NH peak confirmed the completion of copolymerization reaction through different steps. Moreover, clear peaks at 1511 -1 -1 -1 -1 cm , 841 cm and three more peaks in 1100 cm to 1250 cm for –CONH, –OC4H9 and ester linkages in the FT-IR spectrum of PUA copolymer (Fig. 4.2 g), respectively provided additional proof for the synthesis of PUA copolymer. Therefore, the FT-IR spectrum of the final product (Fig. 4.2 g) supported for the proposed structure of the final copolymer.

48

Figure 4.2 FT-IR spectra of AL-1-PCL copolymer series, a. H12MDI, b. PCL, c. PU prepolymer with free NCO groups, d. 2-HEMA, e. vinyl terminated PU prepolymer, f. BA, g. PUA copolymer.

49

The entire observed spectral analysis implied that the reaction was completed step wise and a pre-designed PUA copolymer was synthesized productively.

4.1.3 Chemical characterization of AL-2-PEG copolymer series

The cyclic aliphatic substituted diisocyanate and PEG were used to synthesize PU backbone in AL-2-PEG copolymer series. The monomers used for the preparation of this series were IPDI, PEG, 2-HEMA and BA. The composition and formulation of this series is given below in Table 4.3 and particular FT-IR spectra are shown in Figure 4.3. Table 4.3 Labeling, composition and PU/BA ratio for the different PUA emulsions in AL-2- PEG series Sr. No. Sample no. PU resin composition PU/BA (% )

1. AL-2.1-PEG H12MDI/PEG/HEMA 10/90

2. AL-2.2-PEG H12MDI/PEG/HEMA 20/80

3. AL-2.3-PEG H12MDI/PEG/HEMA 30/70

4. AL-2.4-PEG H12MDI/PEG/HEMA 40/60

In Figure 4.3 FT-IR spectra of all monomers, intermediates and final copolymer are shown in a step wise manner. The FT-IR spectrum of the monomers, PEG (Fig. 4.3 b), 2-HEMA (Fig. 4.3 d) and BA (Fig. 4.3 f) are well discussed before this in section 4.1.1. The FT-IR spectra in Figure 4.3 a presents details of chemical structure of IPDI. There was a characteristic intense peak of –NCO groups in this spectrum at 2257 cm-1 due to diisocyanate groups attached to IPDI. Other prominent peaks were ascribed as: at 2955 cm-1 (asymmetric stretching vibration of aliphatic CH); 2947 cm-1 (symmetric stretching vibration of aliphatic CH); -1 -1 1464 cm (bending vibration of CH in aliphatic CH2 and CH3 groups); 1366 cm (bending -1 vibration of CH2 groups); 1198 cm (twisting of CH in CH2 groups). These observed spectral informations were in accord with previously reported literature (Wu et al., 2001; Xu and Shi, 2005). At first step of synthesis –NCO terminated PU prepolymer was prepared by reacting IPDI with PEG. The FT-IR spectrum of –NCO terminated PU prepolymer is shown in Figure 4.3 c. This spectrum designated the synthesis of –NCO terminated PU prepolymer by reduction in intensity of –NCO peak of IPDI at 2257 cm-1 (Fig. 4.3 a) and replacement of OH peak of PEG at 3375 cm-1 (Fig. 4.3 b) by –NH signals at 3326 cm-1 (Fig. 4.3 c). The complete disappearance of 50

OH peak of PEG and decrease in intensity of –NCO peak of IPDI signified, that at this step of synthesis, OH groups of soft segment are completely utilized with –NCO groups of IPDI to form urethane linkages, but –NCO groups were not consumed completely giving rise to free –NCO terminated PU prepolymer. Also emergence of –NH peak at 3326 cm-1 and a new peak of C=O at 1717 cm-1 were strong verification for the synthesis of urethane linkages. The other peaks in lower frequency region were ascribed as: 1534 cm-1 (–CONH vibrations); 1460 cm-1 (–CHN -1 -1 -1 bending vibrations); 1351 cm (bending vibrations of CH2 groups); 1243 cm and 1109 cm (asymmetric and symmetric stretching vibrations of C-O-C ether groups of PEG). The details observed here are in agreement with reported studies. (Naghash and Abili, 2010) working on the use of silicon containing allylic monomers in PU acrylate hybrid emulsions observed –NH, bending vibration and –CN symmetric stretching vibration at 1535 cm-1 due to –CONH groups of urethanes. While Zia et al. (2009) have reported –CNH bending at 1464 cm-1 during FT-IR descriptions of PU elastomers. At next step of synthesis, unsaturated sites were introduced at the ends of PU prepolymer molecules. For this intention the –NCO terminated PU prepolymer was further extended with 2- HEMA. The free –NCO ends of PU chains reacted with OH groups of 2-HEMA and vinyl terminated PU prepolymer was produced (Fig. 4.3 e). In FT-IR spectrum of vinyl terminated PU prepolymer the complete disappearance of –NCO peak provided proof for this reaction. Also, a peak at 1636 cm-1 due to C=C groups supported the incorporation of acrylate unsaturations into PU backbone. The remaining peaks in this spectrum were assigned as: 1534 cm-1 (–CONH -1 -1 vibrations); 1457 cm (–CHN bending vibrations); 1351 cm (bending vibrations of CH2 groups); 1244 cm-1 and 1108 cm-1 (asymmetric and symmetric stretching vibrations of C-O-C ether groups of PEG). Previously same observations were reported by Xu et al. (2006) during incorporation of 2-HEA into –NCO terminated PU prepolymer. They observed complete disappearance of –NCO peaks and appearance of a new peak at 1637 cm-1 due to stretching vibrations of C=C groups of acrylate. The last step in this synthesis was copolymerization of vinyl terminated PU prepolymer with BA. This vinyl addition led to synthesis of PUA copolymer. The FT-IR spectrum of PUA copolymer is given in Figure 4.3 g.

51

Figure 4.3 FT-IR spectra of AL-2-PEG copolymer series, a. IPDI, b. PEG, c. PU prepolymer with free NCO groups, d. 2-HEMA, e. vinyl terminated PU prepolymer, f. BA, g. PUA copolymer

52

In this spectrum important peaks are at 3368 cm-1 (–NH stretching vibration), 2958 cm-1 and 2872 cm-1 (asymmetric and symmetric stretching of aliphatic CH groups) and 1734 cm-1 (C=O stretching vibration); 1454 cm-1 (–CNH bending); 1112 cm-1 and 1164 cm-1 (C-O-C stretching -1 vibration); 841 cm (stretching of –OC4H9 in ester linkages). It was apparent here in the FT-IR spectrum of PUA copolymer that there was no peak in the region 1500 cm-1 to 1700 cm-1. Therefore, it was concluded that all of the unsaturated sites were completely consumed in vinyl -1 -1 copolymerization. The appearance of –NH, C=O and –OC4H9 peaks at 3369 cm , 1734 cm and 841 cm-1, respectively and disappearance of peaks of –NCO and C=C at 2257 cm-1 and 1636 cm- 1 were strong evidence for the complete step wise synthesis of proposed PUA copolymer at the end.

4.1.4 Chemical characterization of AL-2-PCL copolymer series

The AL-2-PCL copolymer series were synthesized by step wise reaction of IPDI, PCL, 2-HEMA and BA. The FT-IR spectra of all of the monomers, intermediates and final copolymer are shown in Figure 4.4. Basic formulation and composition of this series is given below in Table 4.4. Table 4.4 Labeling, composition and PU/BA ratio for the different PUA emulsions in AL-2- PCL series Sr. No. Sample no. PU resin composition PU/BA (% ) 1. AL-2.1-PCL IPDI/PCL/HEMA 10/90 2. AL-2.2-PCL IPDI/PCL/HEMA 20/80 3. AL-2.3-PCL IPDI/PCL/HEMA 30/70 4. AL-2.4-PCL IPDI/PCL/HEMA 40/60 5. AL-2.5-PCL IPDI/PCL/HEMA 50/50

Individually the FT-IR spectra of all of monomers of this copolymer series have well discussed in previous sections. The FT-IR spectrum of 2-HEMA and BA were explained in section 4.1.1 and that of PCL was described in 4.1.2. Also, spectrum of IPDI have mentioned in 4.1.3. Firstly, IPDI (Fig. 4.4 a) and PCL (Fig. 4.4 b) were reacted to produce –NCO terminated PU prepolymer (Fig. 4.4 c). In the FT-IR spectrum of –NCO terminated PU prepolymer (Fig. 4.4 c) broad OH peak of PCL at 3550 cm-1 was replaced by relatively narrow peak of –NH at 3372 cm- 1and intensity of –NCO peak of IPDI at 2266 cm-1 was reduced. It showed that during this 53 reaction OH groups of PCL were completely reacted with –NCO groups of IPDI and urethane linkages were generated. However, the –NCO groups were not consumed completely giving rise to –NCO terminated PU prepolymer. The remaining important peaks in this spectrum were assigned as: 2948 cm-1 (asymmetric stretching of aliphatic CH groups); 2865 cm-1 (symmetric stretching of aliphatic CH groups); 1732 cm-1 (C=O stretching vibration); 1528 cm-1 (–CONH vibrations); 1462 cm-1 (–CNH bending vibrations); 1102 cm-1, 1163 cm-1 and 1238 cm-1 (stretching vibrations of ester linkages). Previously (Zhang and Zhang, 2004) found similar results when they were studying γ-ray initiated emulsion polymerization of water-borne polyurethane acrylates. They observed peaks for C=O at 1732 cm-1, –NH at 1534 cm-1 and three consecutive peaks at 1145 cm-1 to 1240 cm-1 for ester linkages. Further –NCO terminated PU prepolymer was extended with 2-HEMA (Fig. 4.4 d) to produce vinyl terminated PU prepolymer (Fig. 4.4 e). In this reaction free –NCO groups of PU prepolymer were reacted with OH groups of 2-HEMA and more urethane linkages were created in PU backbone along with the incorporation of unsaturations at the ends of chains. In the FT-IR spectrum of vinyl terminated PU prepolymer (Fig. 4.4 e) perceptible changes were at three places; increase in intensity of –NH peak at 3375 cm-1 due to additional formation of urethane linkages, disappearance of –NCO peak at 2266 cm-1 indicating the complete utilization of these groups and appearance of C=C peak at 1637 cm-1 confirmed the addition of acrylate unsaturations at the ends of PU prepolymer chains. The other peaks in this spectrum were accredited as: 1728 cm-1 (C=O stretching vibrations); 1535 cm-1 (–CONH vibrations); 1466 cm-1 (bending vibrations of –CNH); 1239 cm-1, 1163 cm-1 and 1095 cm-1 (stretching vibrations of ester linkages). Similar findings were reported by He et al. (2010) for incorporation of acrylate into PU backbone when they were synthesizing UV curable multi-functional polyurethane acrylate containing 3-(2-hydroxyethyl) isocyanurate. They examined –NH stretching vibration at 3372 cm-1, C=C stretching vibration at 1634 cm-1, C=O characteristic stretching vibration at 1727 cm-1 and three peaks at 1300 cm-1 to 1050 cm-1 for ester linkages. At the final step of synthesis vinyl terminated PU prepolymer (Fig. 4.4 e) was copolymerized with BA (Fig. 4.4 f) through emulsion polymerization. To investigate the vibrational mode changes in final product, PUA copolymer FT-IR spectrum was recorded. The Figure 4.4 g presents detailed FT-IR spectrum of final product i.e. PUA copolymer.

54

Figure 4.4 FT-IR spectra of AL-2-PCL copolymer series, a. IPDI, b. PCL, c. PU prepolymer with free NCO groups, d. 2-HEMA, e. vinyl terminated PU prepolymer, f. BA, g. PUA copolymer

55

In functional group region prominent peaks were; 3370 cm-1 (–NH stretching vibration); 2959 cm-1 (asymmetric stretching of aliphatic CH groups); 2873 cm-1 (symmetric stretching vibration of aliphatic CH groups); 1734 cm-1 (C=O stretching vibration). The functional group region, 1700 cm-1 to 1500 cm-1 related to double bond (C=C) characteristic stretching vibrations was completely clear indicating the complete utilization of unsaturation sites during vinyl copolymerization. The other peaks in lower frequency region were at 1453 cm-1 for –CNH bending vibrations, 1250 cm-1, 1164 cm-1 and 1114 cm-1 due to stretching vibrations of ester -1 linkages and 842 cm because of –OC4H9 groups in copolymer chains. The appearance of -1 -1 -1 characteristic peaks of –NH, –CNH and –OC4H9 at 3370 cm , 1453 cm and 842 cm , respectively provided a strong proof for synthesis of PUA copolymer. Also disappearance of characteristic peaks of –NCO and C=C at 2257 cm-1 and 1638 cm-1, respectively were additional clues to support the synthesis of PUA copolymer through proposed route.

4.1.5 Chemical characterization of AR-3-PEG copolymer series

The AR-3-PEG copolymer series was also synthesized in this study by using aromatic diisocyanate, TDI, PEG, 2-HEMA and BA. The details of five copolymers prepared and composition is given in Table 4.5. Table 4.5 Labeling, composition and PU/BA ratio for the different PUA emulsions in AR-3- PEG series Sr. No. Sample no. PU resin composition PU/BA (% ) 1. AR-3.1-PEG TDI/PEG/HEMA 10/90 2. AR-3.2-PEG TDI/PEG/HEMA 20/80 3. AR-3.3-PEG TDI/PEG/HEMA 30/70 4. AR-3.4-PEG TDI/PEG/HEMA 40/60 5. AR-3.5-PEG TDI/PEG/HEMA 50/50

The FT-IR spectra of all of the monomers, intermediates and final product are displayed systematically in Figure 4.5. The spectra of monomers 2-HEMA, BA and PEG are discussed in section 4.1. The first two steps of synthesis, i.e. synthesis of –NCO terminated PU prepolymer and further its extension with 2-HEMA were very fast in the preparation of this series, hence, it was not possible to record the FT-IR spectrum of –NCO terminated PU prepolymer. Therefore, 56 directly vinyl terminated PU prepolymer was characterized by FT-IR after completion of first two steps. The FT-IR spectrum of TDI (Fig. 4.5 a) showed a very intense characteristic stretching vibration peak of –NCO at 2265 cm-1 along with complex lower spectral region. The other important peaks -1 -1 in FT-IR spectrum of TDI were assigned as: 2923 cm (stretching of CH of CH3); 1781 cm and 1721 cm-1 (overtones related to aromatic structure); 1615 cm-1, 1577 cm-1 and 1524 cm-1 (C-C stretch in aromatic ring); 1261 cm-1 (in plane bending of aromatic CH groups); 815 cm-1 (out of plane bending of aromatic CH groups); 785 cm-1 and 702 cm-1 (bending vibration of aromatic CH groups). Because of aromatic ring sp2 CH stretch near 3000 cm-1 was not so strongly visible. However, C-C stretch in aromatic ring at 1616 cm-1, 1577 cm-1 and 1524 cm-1 confirmed the aromatic structure of TDI. Additionally, two relatively weak overtones at 1781 cm-1 and 1721 -1 cm supported aromatic characteristic of this particular isocyanate. Here observations of FT-IR spectrum of TDI are in accord well with previously reported literature. Xu et al. (2004) reported stretching of C-C in benzene ring at 1600 cm-1 and 1538 cm-1. Also, they observed in plane and out of plane bending vibration of aromatic CH groups at 1280 cm-1 and 811 cm-1, respectively. Wu et al. (2001) observed bending vibration of aromatic CH groups at 761 cm-1 and 700 cm-1 while working on the synthesis of polyurethane acrylate latex films. At the first step of synthesis –NCO groups of TDI were reacted with OH groups of PEG to produce –NCO terminated PU prepolymer. After that OH groups of 2-HEMA (Fig. 4.5 d) approached to free –NCO ends of PU prepolymer and more urethane linkages were generated giving rise to the structure of vinyl terminated PU prepolymer (Fig. 4.5 e). The FT-IR spectrum of vinyl terminated PU prepolymer showed a strong peak at 3459 cm-1 due to stretching of –NH groups of urethane linkages, two adjacent peaks at 2950 cm-1 and 2868 cm-1 for asymmetric and symmetric stretching of CH in CH2 groups respectively, stretching vibration peak of C=O groups at 1714 cm-1 and C=C stretching vibration at 1660 cm-1. The disappearance of –NCO at 2265 cm- 1 and appearance of new peaks due to –NH, C=O and C=C at 3359 cm-1, 1714 cm-1 and 1660 cm- 1 were strong proves for completion of first two steps of synthesis in preparation of AR-3-PEG series. The remaining peaks in lower frequency region were assigned as: 1537 cm-1 and 1504 cm- 1 -1 -1 (aromatic C-C stretching vibration); 1439 cm (=CH2 bending vibration); 1386 cm ( bending -1 -1 vibration of CH in CH2 groups); 1297 cm (in plane bending of aromatic CH groups); 1255 cm and 1092 cm-1 (asymmetric and symmetric stretching of C-O-C groups of ether linkages); 818 57

-1 cm (out of plane bending of CH in acrylate =CH2 groups). These FT-IR findings are in agreement with previously reported literature. Zhang et al. (2010) working on UV-curable water- -1 borne polyurethane acrylate, have accepted the peaks of C=C, =CH2 and =CH at 1660 cm , 1460 cm-1 and 845 cm-1 as a sign for incorporation of acrylate into PU backbone. So, here it can be concluded that acrylate moieties were assimilated with PU backbone and vinyl terminated PU prepolymer was ready for further extension. The vinyl terminated PU prepolymer (Fig. 4.5 d) was copolymerized in aqueous medium with BA (Fig. 4.5 e) and PUA copolymer (Fig. 4.5 e) was produced at the end of synthesis process. The FT-IR spectrum of final product showed an intense peak at 3402 cm-1 owing to stretching vibration of –NH groups of urethane linkages, three consecutive peaks at 2965 cm-1, 2960 cm-1 and 2873 cm-1 due to stretching vibrations of aliphatic CH groups and a strong peak at 1735 cm-1 related to stretching vibration of C=O groups. The other peaks in lower frequency region were : 1453 cm-1 and 1397 cm-1 (aromatic C-C stretching vibration); 1250 cm-1, 1164 cm-1 and 1113 -1 -1 cm ( stretching vibrations of ether and ester linkages); 841 cm (stretching of –OC4H9 in ester linkages). According to the previous findings (Lu and Larock, 2007) while synthesizing PUA -1 hybrids found typical absorption peak for the –OC4H9 group at 841 cm , indicating the existence of the acrylics in the hybrid latex. However, they observed the shift in absorption of the C=O groups towards higher frequency, concluding that the intra- and intermolecular hydrogen bonds of the PU have been destroyed due to grafting of the acrylics and entanglement of the macromolecular chains between the PU and acrylates, leading to good miscibility of the resulting hybrid latexes. Same observations i.e. shift of C=O absorption towards higher frequency region, were found here during preparation of the AR-3-PEG copolymer series. The appearance of –NH and C=O peaks and disappearance of –NCO and C=C characteristic peaks provided strong evidences for step wise synthesis of PUA copolymer. In addition, aromatic C-C stretching peaks -1 -1 -1 at 1453 cm and 1397 cm and –OC4H9 peak at 841 cm supported the proposed structure of PUA copolymer.

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Figure 4.5 FT-IR spectra of AR-3-PEG copolymer series, a. TDI, b. PEG, c. PU prepolymer with free NCO groups, d. 2-HEMA, e. vinyl terminated PU prepolymer, f. BA, g. PUA copolymer

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4.1.6 Chemical characterization of AR-3-PCL copolymer series

The AR-3-PCL copolymer series were synthesized from monomers TDI, PCL, 2-HEMA and BA. Basic formulation and composition is presented below in Table 4.6 and to explain molecular structural details relative FT-IR spectra are displayed in Figure 4.6. Table 4.6 Labeling, composition and PU/BA ratio for the different PUA emulsions in AR-3- PCL series Sr. No. Sample no. PU resin composition PU/BA (% ) 1. AR-3.1-PCL TDI/PCL/HEMA 10/90 2. AR-3.2-PCL TDI/PCL/HEMA 20/80 3. AR-3.3-PCL TDI/PCL/HEMA 30/70 4. AR-3.4-PCL TDI/PCL/HEMA 40/60 5. AR-3.5-PCL TDI/PCL/HEMA 50/50

In Figure 4.6 FT-IR spectra of all of the monomers, PU prepolymers and copolymer of AR-3- PCL copolymer series are displayed. The FT-IR spectra of 2-HEMA, BA, PCL and TDI are already discussed in sections 4.1.1, 4.1.2 and 4.1.5, respectively. By reacting appropriate amounts of PCL (Fig. 4.6 a) and TDI (Fig. 4.6 a), –NCO terminated PU prepolymer was produced at the initial stage of synthesis. The detailed FT-IR spectrum of –NCO terminated PU prepolymer is given in Figure 4.6 c. The important perceptible peaks in functional group region of this spectrum were: 3342 cm-1 (stretching vibration of –NH in urethane linkages); 2945 cm-1 (asymmetric stretching of aliphatic CH groups); 2865 cm-1 (symmetric stretching of aliphatic CH groups); 2272 cm-1 (free –NCO groups of PU prepolymer); 1735 cm-1 (stretching vibration of C=O). It was clear by comparing the first three FT-IR spectra (Fig. 4.6 a, b, c) that broad OH peak of PCL was replaced by relatively narrow –NH peak at lower frequency 3343 cm-1. However, a relatively less intense band of –NCO is still visible at 2272 cm- 1presenting the availability of free –NCO groups for next step of synthesis. These characteristic changes supported the synthesis of –NCO terminated PU prepolymer. The other peaks in lower frequency region were assigned as: 1618 cm-1, 1596 cm-1 and 1534 cm-1 (stretching vibration of aromatic C-C); 1459 cm-1 (bending vibration of CH groups of soft segment); 1223 cm-1, 1190

60 cm-1 and 1065 cm-1 ( stretching vibration of ester linkages of soft segment); 770 cm-1 and 735 cm-1 (bending vibration of aromatic CH groups). The –NCO terminated PU prepolymer was further extended with 2-HEMA (Fig. 4.6 d) to produce vinyl terminated PU prepolymer. Hence, OH groups of 2-HEMA reacted with free – NCO ends of PU prepolymer generating additional urethane linkages in the backbone of PU chains. The FT-IR spectrum of vinyl terminated PU prepolymer is presented in Figure 4.6 e. The prominent peaks in this spectrum were: 3340 cm-1 (stretching vibration of –NH groups in urethane linkages); 2950 cm-1 (asymmetric stretching of aliphatic CH groups); 2865 cm-1 (symmetric stretching of aliphatic CH groups); 2273 cm-1 (–NCO stretching); 1731 cm-1 (stretching vibration of C=O) ; 1639 cm-1 (stretching vibration of C=C); 1620 cm-1, 1599 cm-1 and 1537 cm-1 ( stretching vibration of aromatic C-C); 1454 cm-1; 1224 cm-1, 1162 cm-1 and 1071 cm-1 (characteristic vibrations of ester linkages); 769 cm-1 and 736 cm-1 (bending vibration of aromatic CH groups). At the last step of synthesis unsaturated sites of BA were copolymerized with vinyl ends of vinyl terminated PU prepolymer. The FT-IR spectra of BA and final product PUA copolymer are displayed in Figure 4.6 f and g respectively. Typical peaks in FT-IR spectrum of PUA copolymer were accredited as: 3388 cm-1 (stretching vibration of –NH in urethane linkages); 2958 cm- 1(asymmetric stretch of aliphatic CH groups); 2872 cm-1(symmetric stretch of aliphatic CH groups); 1734 cm-1 (C=O stretching vibration); 1452 cm-1 (bending of aliphatic CH groups); 1250 cm-1, 1164 cm-1 and 1114 cm-1 (stretching of ester linkages); 840 cm-1 (stretching of ester – -1 -1 OC4H9 groups); 741 cm (bending of aromatic CH groups). The IR region from 1500 cm to 1700 cm-1 was completely clear indicating complete consumption of unsaturated sites in vinyl -1 emulsion copolymerization. Also, appearance of –NH and –OC4H9 peaks at 3388 cm and 840 cm-1 were strong clues for complete synthesis of PUA through particular proposed chemical path.

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Figure 4.6 FT-IR spectra of AR-3-PCL copolymer series, a. TDI, b. PCL, c. PU prepolymer with free NCO groups, d. 2-HEMA, e. vinyl terminated PU prepolymer, f. BA, g. PUA copolymer

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4.2 Physical properties of PUA copolymer emulsions

The physical colloidal properties like micelle size, polydispersity index (PDI), particle size distribution (PSD), stability and physical appearance of PUA emulsions are important parameters in deciding the end use of products. These parameters not only affect the processability of coatings, also the properties of cured films. The micelle size and polydispersity index (PDI) of every sample of PUA copolymer emulsions were measured using light scattering apparatus. It is worthwhile to note that the particle size has a direct effect on the stability of emulsions and the colloidal stability of water-borne systems is a very important characteristic, which determines their safe storage period. The emulsions with larger micelle sizes (>1,000 nm) are generally unstable, while with the small micelle size (<200 nm) are considered to be storage-stable (Asif et al., 2004). In commercial point of view, the stability of emulsions is an important basic parameter. In present study PUA emulsions with nano sized micelles were prepared successfully. PU molecular chains with vinyl terminals undergo vinyl addition with unsaturated sites of BA. Resulting copolymer was a cross-linked copolymer with micelle sizes in the range of nm scale. The concentrations of vinyl terminated PU prepolymer and BA were assorted progressively. Also, different diisocyanates and polyols were tried in synthesis of PU prepolymer in order to study the effect of variation in chemistry of these monomers on properties of final copolymer. The micelle size of final copolymer depends upon several factors like hydrophilicity of monomers, molecular weight of prepolymer and flexibility of main chain (Kim and Lee, 1995). In general the micelle size of PUA emulsions was decreased with decrease in concentration of BA, but few exceptions were observed as well. The experimental sets of PUA emulsions were kept in air tight sample bottles, stored at room temperature for a period of approx. six months and evaluated for any kind of phase separation in order to note the stability of samples. To maintain the similarity of systems for appropriate comparison, the concentration of emulsifier was constant throughout the whole research work. The micelle size, PDI and other physical properties like stability and appearance of PUA emulsions were studied and discussed here in this section.

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4.2.1 Micelle size, PDI, stability and appearance of PUA emulsions of AL-1-PCL copolymer series

The micelle size of emulsions in AL-1-PCL series was ranged between 40.2 nm to 198.4 nm. A glance of Table 4.7 reveals that micelle size was increased as PU/BA ratio increased from 47.1 nm to 198.4 nm initially, but after this it was decreased again progressively. Table 4.7 Sample code, composition, micelle size, PDI, stability and appearance of PUA emulsions of AL-1-PCL copolymer series. Micelle PU/BA Sample code Composition size PDI Stability Appearance (% ) (nm) H MDI:PCL:HEMA: AL-1.1-PCL 10/90 12 47.1 0.148 Stable Translucent BA H MDI:PCL:HEMA: AL-1.2-PCL 20/80 12 53.3 0.046 Stable Translucent BA H MDI:PCL:HEMA: AL-1.3-PCL 30/70 12 198.4 0.717 Stable White BA H MDI:PCL:HEMA: AL-1.4-PCL 40/60 12 84.6 0.328 Stable White BA H MDI:PCL:HEMA: AL-1.5-PCL 50/50 12 40.2 0.216 Stable Translucent BA

These micelle sizes are analogous to the sizes reported by Asif et al. (2004). They prepared a series of water-borne, polyurethane acrylates for aqueous dispersions. During this preparation they reported the average micelle sizes of aqueous dispersions from 43 nm–237 nm, measured by laser light scattering. The graphical presentation of particle size distribution of AL-1-PCL series is shown in Figure 4.7. In the process of copolymerization, firstly BA was charged along with emulsifier and some other ingredients as mentioned in Table 3.1. So, monomer-swollen particles of BA were generated. Inside these monomer-swollen particles of BA, copolymerization was carried out. It is possible that when PU/BA concentration was increased from 10/90 to 30/70 %, the chance of copolymerization was increased resulting in large micelles of cross linked copolymer along with the tendency of acrylates to swell. But after that, the concentration of BA was low regarding to swelling of monomer-swollen particles, generating relatively smaller micelle size even concentration of PU was increased further. The micelle size found here in this series was comparatively higher regarding all other series, also, first increasing and then decreasing trend of micelle size was observed just here and might be attributed to higher 64 molecular weight of PU prepolymer (Kim et al., 2006). All of these emulsions were translucent to white in appearance and quite stable even after six months of preparation. These physical aspects suggested industrial application of these PUA emulsions, having an elegant shelf life, in textile finishing without any loss in color quality of fabrics.

Figure 4.7 Particle size distribution of PUA emulsions of AL-1-PCL copolymer series

4.2.2 Micelle size, PDI, stability and appearance of PUA emulsions of AL-2-PCL copolymer series

The micelles of PUA emulsions in AL-2-PCL series were nano sized in a quite close range 52.1 nm - 58.0 nm with narrow PDI i.e. 0.1- 0.2. The narrow PDI presents close particle size distribution (PSD) in emulsions; it is also evident in Figure 4.8. The micelle size of these emulsions was very fine as compared to reported literature. Asif et al. (2009) prepared a series of polyurethane acrylate dispersions with micelle size ranged from 48.2 nm to 75.3 nm. While Zhu et al. (2008) observed micelle size of PUA hybrids, 47.19 nm-127.00 nm. Lu and Larock (2007) stated that micelles diameter in PUA emulsions barely increases with

65 an increase in the acrylics content, when emulsions are prepared by simple emulsion polymerization process as compared to seeded emulsion polymerization. Same observations were found here in this study. Table 4.8 Sample code, composition, micelle size, PDI, stability and appearance of PUA emulsions of AL-2-PCL copolymer series Micelle PU/BA Sample code Composition size PDI Stability Appearance (% ) (nm) IPDI:PCL:HEMA AL-2.1-PCL 10/90 58.0 0.207 Stable Translucent :BA IPDI:PCL:HEMA AL-2.2-PCL 20/80 56.6 0.138 Stable Translucent :BA IPDI:PCL:HEMA AL-2.3-PCL 30/70 56.0 0.11 Stable Translucent :BA IPDI:PCL:HEMA AL-2.4-PCL 40/60 56.0 0.0836 Stable Translucent :BA IPDI:PCL:HEMA AL-2.5-PCL 50/50 52.1 0.137 Stable Translucent :BA

Overall micelle size was increased with an increase in acrylic content but this increase was not significant. The small micelle size of emulsions is very important for the stability of emulsions. All of the emulsions in this series were quite stable with translucent appearance even after six months of preparation. The copolymer micelles in this series are smaller in size as compared to the last one AL-1-PCL series. This change can be attributed to difference in hydrophilic nature of two different diisocyanates; H12MDI has two 6-carbon rings while in chemical structure of IPDI just one 6-carbon ring is available. So, nature of IPDI is relatively less hydrophobic. This hydrophilicity helped in preparation of more stable emulsions with fine particle size. Asif et al. (2009) supported this observation by stating that greater hydrophilicity of monomers results in smaller micelle size.

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Figure 4.8 Particle size distribution of PUA emulsions of AL-2-PCL copolymer series.

4.2.3 Micelle size, PDI, stability and appearance of PUA emulsions of AR-3-PCL copolymer series

The micelle size of PUA emulsions of AR-3-PCL copolymer series decreased regularly with decrease in acrylic content from 61.0 nm to 42.7 nm while PU/BA ratio was changed from 10/90 to 40/60. The polydispersity index (PDI) was very low for these first four emulsions ranging from 0.04 to 0.1, providing an evidence for the long run stability of these emulsions. The decrease in micelle size of acrylic polyurethane hybrid emulsions with decrease in acrylic content was also observed by Šebenik et al. (2003). Table 4.9 Sample code, composition, micelle size, PDI, stability and appearance of PUA emulsions of AR-3-PCL copolymer series PU/BA Micelle Sample code Composition PDI Stability Appearance (% ) size (nm) AR-3.1-PCL 10/90 TDI:PCL:HEMA:BA 61 0.119 Stable Creamy AR-3.2-PCL 20/80 TDI:PCL:HEMA:BA 53.5 0.0497 Stable Creamy AR-3.3-PCL 30/70 TDI:PCL:HEMA:BA 51.2 0.118 Stable Creamy AR-3.4-PCL 40/60 TDI:PCL:HEMA:BA 42.7 0.136 Stable Creamy AR-3.5-PCL 50/50 TDI:PCL:HEMA:BA 768.5 0.869 Stable Creamy

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They stated that secondary intermolecular binding forces between acrylic and PU components results in a reduction in hydrodynamic volume of macromolecular chains, giving rise to nano sized micelles. The studies by Asif et al. (2009) recognized that polar aromatic rings in PU backbone help in getting better position for the urethane polar units which could develop the external hydrogen bonding. This particular type of behavior is not possible in alicyclic and aliphatic polyurethanes.

Figure 4.9 Particle size distribution of PUA emulsions of AR-3-PCL copolymer series (The micelle size of AR-3.5-PCL was divided by 10 for graphical adjustment)

However, the micelle size and PDI of the last one emulsion, AR-3.5-PCL, with lowest BA content was relatively astonishing in this series. This difference can also be observed in PSD curves in Figure 4.9. Such large size exception in micelle size of emulsion predicted decrease in stable shelf life of sample. Because of aromatic structure of TDI, a noticeable creamy (slightly pale) appearance was observed as compared to other PUA emulsions with aliphatic diisocyanates. This hitch in appearance of emulsions might have a negative effect on color quality of fabrics in textile applications. All above discussed three series were based on polyester soft segment, PCL diol. The trends in micelle size, PDI, PSD and stability were more regular in these results. Polyether based soft 68 segment, PEG was used in the next three PUA copolymer emulsion series. It was observed that in these PUA emulsions trends in micelle size, PDI, PSD and stability were less regular as compared to the polyester based emulsions. This difference can be explained on the basis of chemical structure of these two different soft segments. The polyester polyol, PCL has more polar structure due to polar carbonyl groups while no such groups are observed in polyether based soft segment as PEG. Ultimately the nature of PU prepolymer based on PCL was more flexible leading towards more regular changes and stable shelf life of emulsions. While on the other hand PU prepolymers based on PEG might be less flexible and comparatively hydrophobic in nature resulting in irregular trends in properties of emulsions and decreased storage life. Sebenik and Krajnc, (2004) studied semibatch emulsions of methyl methacrylate with different polyurethane particles. They concluded that if polyester polyol was used, PU chains were more flexible and consequently smaller sized micelles were generated, while with polyether based polyol, wide scattered, large size micelles were produced.

4.2.4 Micelle size, PDI, stability and appearance of PUA emulsions of AL-1-PEG copolymer series

The size of micelles in AL-1-PEG series was ranged between 40.3 nm to 322.3 nm but trend was entirely irregular. It might be due to less polar polyether based soft segment as discussed above in section 4.2.3. The PDI of emulsions with different PU/BA ratio was 0.136-0.862, presenting wide scattered PSD. The PSD is demonstrated in Figure 4.10. This figure presents narrow PSD peaks for AL-1.1-PEG, AL-1.2-PEG and AL-1.3-PEG but wide scattered distribution peaks for AL-1.4-PEG and AL-1.5-PEG. First three emulsions with PU/BA ratios of 10/90, 20/80 and 30/70 were quite stable even after six months of preparation, but the next two with PU/BA, 40/60 % and 50/50 % were coagulated after few days of preparation. This particular difference in stability of emulsions can also be predicted by difference in size of micelles and PDI given in Table 4.10. The micelle sizes of first three emulsions were < 100 nm with low PDI, very suitable for the long stable shelf life. However, for the last two emulsions, sizes of the micelles were 322.3 nm and 107.3 nm. These emulsions having bigger micelles showed high tendency towards coagulation consequently having relatively shorter storage life. These emulsions were translucent to white in appearance, therefore could be applied on colored fabrics without any chances of

69 change in shade. So, stable emulsions up to 30/70 % PU/BA with small micelle size and narrow PDI might be suitable for textile applications. Table 4.10 Sample code, composition, micelle size, PDI, stability and appearance of PUA emulsions of AL-1-PEG copolymer series Micelle PU/BA Sample code Composition size PDI Stability Appearance (% ) (nm) H MDI:PEG:HEMA: AL-1.1-PEG 10/90 12 52.6 0.195 Stable Translucent BA H MDI:PEG:HEMA: AL-1.2-PEG 20/80 12 92.4 0.463 Stable Translucent BA H MDI:PEG:HEMA: AL-1.3-PEG 30/70 12 40.3 0.136 Stable Translucent BA H MDI:PEG:HEMA: AL-1.4-PEG 40/60 12 322.3 0.862 Coag.a White BA H MDI:PEG:HEMA: AL-1.5-PEG 50/50 12 107.3 0.557 Coag.a White BA a coagulated after few days of preparation

Figure 4.10 Particle size distribution of PUA emulsions of AL-1-PEG copolymer series

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4.2.5 Micelle size, PDI, stability and appearance of PUA emulsions of AL-2-PEG copolymer series

The AL-2-PEG copolymer series were prepared by IPDI, PEG, 2-HEMA and BA. The preparation of just three stable emulsions, AL-2.1-PEG, AL-2.2-PEG and AL-2.3-PEG (10/90, 20/80 and 30/70 %) was possible as mentioned in Table 4.11. The PSD of all of these stable emulsions is presented below in Figure 4.11. In this figure all of the peaks are smoothly distributed demonstrating average micelle size near 60 nm. With this small micelle size stable emulsions could be expected. Actual results were in well agreement with these expectations. These emulsions were translucent to white and quite stable after preparation, well suited for textile applications. The next emulsion with PU/BA, 40/60 ratio was coagulated during preparation, so, its further characterization was impossible. Keeping in view this outcome, further higher PU/BA ratio was not applied. This conduct of unstability of emulsions at higher concentrations of monomers can be attributed to relatively more hydrophobic nature of PEG than polyester based polyol (Šebenik and Krajnc, 2005). Table 4.11 Sample code, composition, micelle size, PDI, stability and appearance of PUA emulsions of AL-2-PEG copolymer series Micelle PU/BA Sample code Composition size PDI Stability Appearance (% ) (nm) IPDI:PEG:HEMA: AL-2.1-PEG 10/90 62.8 0.211 Stable Translucent BA IPDI:PEG:HEMA: AL-2.2-PEG 20/80 60 0.182 Stable White BA IPDI:PEG:HEMA: AL-2.3-PEG 30/70 64.3 0.284 Stable Translucent BA IPDI:PEG:HEMA: AL-2.4-PEG 40/60 ------coagulated a Translucent BA a coagulated just at the end of preparation

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Figure 4.11 Particle size distribution of PUA emulsions of AL-2-PEG copolymer series

4.2.6 Micelle size, PDI, stability and appearance of PUA emulsions of AR-3-PEG copolymer series

The AR-3-PEG copolymer series was synthesized by using aromatic diisocyanates, TDI. It was difficult to control the viscosity of vinyl PU prepolymer; so, a small amount of organic solvent, dry DMF was added. All of the emulsions in this series were quite stable with micelle size 68.5 nm to 76.9 nm having small PDI (0.1-0.2). The PSD of these emulsions is presented in Figure 4.12. This figure shows an even distribution of copolymer micelles, with average size of micelles < 100 nm. The data given in Table 4.12 reveals that overall micelle size decreases with a decrease in BA content, but this trend was slightly irregular. The probable justification for decrease in micelle size with the decrease in BA content has given in section 4.2.1. Almost same observations were made by Zhu et al. (2008) and Aznar et al. (2006). They concluded from independent studies on polyurethane acrylates, that micelle size of PUA copolymer increases with an increase in acrylic content and vice versa. The physical appearance of these emulsions was creamy and became more and more unclear as concentration of TDI containing PU prepolymer was increased. It would interrupt negatively in application of these PUA copolymer emulsions in textiles. However, dilution of emulsions with water could overcome this liability.

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The PSD curves of all series of copolymers are unimodal, indicating absence of any secondary particle coalescence. Table 4.12 Sample code, composition, micelle size, PDI, stability and appearance of PUA emulsions of AR-3-PEG copolymer series Micelle PU/BA Sample code Composition size PDI Stability Appearance (% ) (nm) AR-3.1-PEG 10/90 TDI:PEG:HEMA:BA 76.2 0.133 Stable Creamy AR-3.2-PEG 20/80 TDI:PEG:HEMA:BA 76.9 0.207 Stable Creamy AR-3.3-PEG 30/70 TDI:PEG:HEMA:BA 70.4 0.113 Stable Creamy AR-3.4-PEG 40/60 TDI:PEG:HEMA:BA 68.5 0.211 Stable Creamy AR-3.5-PEG 50/50 TDI:PEG:HEMA:BA 72.4 0.122 Stable Creamy

Figure 4.12 Particle size distribution of PUA emulsions of AR-3-PEG copolymer series

4.3 Viscosity and solid contents of PUA emulsions

Viscosity and solid contents are important features of water based PUA copolymers, with respect to process ability and quality of end product. It is worthwhile to measure the viscosity of dispersion as a function of solid contents, because for water-borne system, water must be evaporated at the time of application. Thus, in terms of energy efficiency an agreement between solid contents and viscosity are important. The viscosity arises from the interaction among the

73 particles in system. Therefore, it is evident that there are many different factors such as molecular architecture, molecular weight, volume of a molecule and intermolecular chain entanglement and solid contents, which affect the viscosity of a final copolymer (Asif et al., 2009). However, viscosity of water-borne systems can be controlled easily by adjusting the amount of solvent. Viscosity of PUA emulsions was measured by a Brookfield DV-II + Pro viscometer using UL adapter spindle. The spindle of viscometer was rotated in emulsion sample and viscosity was recorded on screen readily. While dry weight contents or solid contents (%) of PUA emulsions were determined by gravimetric method. It was executed by placing a weighed amount of emulsions at 50 oC to 60 oC in oven for 24-48 hrs. These samples were weighed again till a constant weight. The dry weight contents were calculated according to following formula

% dry weight = Wb/Wa * 100 Where Wa is weight of sample before drying and Wb is weight after drying.

4.3.1 Viscosity and solid contents of PUA emulsions of AL-1-PCL copolymer series

The viscosity and solid contents of AL-1-PCL copolymer series were decreased gradually with increase in PU/BA ratio. The decrease in these two parameters with variation in PU/BA ratio is presented below in Figures 4.13 and 4.14 and Table 4.13. When PU/BA ratio increased from 10/90 to 50/50, solid contents decreased from 38.15 % to 28.60 %. Sultan et al. (2011) has reported 35.32 % and 38.28 % solid contents when they were studying modification of cellulosic fibre with polyurethane acrylate copolymers, Part I: Physicochemical properties. The viscosity of emulsions also decreased from 50.6 cps to 17.4 cps with decrease in concentration of BA. The micelle size was also decreased with the same trend as reported in section 4.2.1. By the addition of BA at the initial stage of emulsion polymerization, monomer-swollen particles were generated. When vinyl terminated PU prepolymer was introduced, copolymerization was carried out inside these monomer-swollen particles. It is possible that at higher concentrations of BA monomer-swollen particles were richer in concentration of monomer with greater ability of acrylate to swell as compared to the situation when concentration was lower.

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Table 4.13 Sample code, composition, solid contents and viscosity of PUA emulsions of AL- 1-PCL copolymer series. Solid Viscosity Sr. No. Sample code PU/BA (% ) Composition contents (cps) (%) 1. AL-1.1-PCL 10/90 H12MDI:PCL:HEMA:BA 38.15 50.6 2. AL-1.2-PCL 20/80 H12MDI:PCL:HEMA:BA 37.04 29.2 3. AL-1.3-PCL 30/70 H12MDI:PCL:HEMA:BA 32.7 17.1 4. AL-1.4-PCL 40/60 H12MDI:PCL:HEMA:BA 28.86 15.3 5. AL-1.5-PCL 50/50 H12MDI:PCL:HEMA:BA 28.60 17.4

This inclination has already been proved by variation in size of micelles of emulsions. Consequently, at higher concentrations of BA comparatively larger copolymer micelles could have greater intermolecular entanglements causing resistance in flow of emulsion while at lower concentrations smaller particles could move more easily.

Figure 4.13 Variation in viscosity (cps) of PUA emulsions of AL-1-PCL copolymer series with variation in PU/BA %

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Figure 4.14 Variation in solid contents (%) of PUA emulsions of AL-1- PCL copolymer series with variation in PU/BA %

4.3.2 Viscosity and solid contents of PUA emulsions of AL-2-PCL copolymer series

The AL-2-PCL copolymer series showed a progressive decrease in viscosity and solid contents with decrease in BA concentration. According to the data presented in Table 4.14 and Figures 4.15 and 4.16, solid contents of emulsions in this series varies from 47.27 % to 41.73 % and viscosity from 98.2 cps to 11.8 cps. Similar observations were made by (Asif and Shi, 2004) in solid contents and viscosity measurements of water-borne polyurethane acrylate dispersions. They stated that decrease in solid contents results in a decrease in viscosity because decrease in solid contents result in change in orientation of prepolymeric molecular chains, thus destroying the associated structures such as hydrogen bonding and other chain entanglements. As a result flow resistance decreases and viscosity is reduced. Table 4.14 Sample code, composition, solid contents and viscosity of PUA emulsions of AL- 2-PCL copolymer series. Solid Viscosity Sr. No. Sample code PU/BA (%) Composition contents (%) (cps) 1. AL-2.1-PCL 10/90 IPDI:PCL:HEMA:BA 47.27 98.2 2. AL-2.2-PCL 20/80 IPDI:PCL:HEMA:BA 44 57.6 3. AL-2.3-PCL 30/70 IPDI:PCL:HEMA:BA 41 36.2 4. AL-2.4-PCL 40/60 IPDI:PCL:HEMA:BA 40.6 18.1 5. AL-2.5-PCL 50/50 IPDI:PCL:HEMA:BA 40.5 11.8

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Figure 4.15 Variation in viscosity (cps) of PUA emulsions of AL-2-PCL copolymer series with variation in PU/BA %

Figure 4.16 Variation in solid contents (%) of PUA emulsions of AL-2- PCL copolymer series with variation in PU/BA %

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4.3.3 Viscosity and solid contents of PUA emulsions of AR-3-PCL copolymer series

The AR-3-PCL copolymer series were prepared by using aromatic diisocyanates, TDI. Asif et al. (2009) stated that more rigid aromatic rings can produce more flexible PU prepolymer and different intraparticle secondary forces like hydrogen bonding between urethane and urea linkages and other chain entanglements were formed more rapidly. Table 4.15 Sample code, composition, solid contents and viscosity of PUA emulsions of AR- 3-PCL copolymer series. Solid contents Viscosity Sample code PU/BA (%) Composition Sr. No. (%) (cps) 1. AR-3.1-PCL 10/90 TDI:PCL:HEMA:BA 35.5 43.2 2. AR-3.2-PCL 20/80 TDI:PCL:HEMA:BA 34.66 41.3 3. AR-3.3-PCL 30/70 TDI:PCL:HEMA:BA 33.56 33.3 4. AR-3.4-PCL 40/60 TDI:PCL:HEMA:BA 32.6 28.1 5. AR-3.5-PCL 50/50 TDI:PCL:HEMA:BA 29.19 14.1

Figure 4.17 Variation in viscosity (cps) of PUA emulsions of AR-3-PCL copolymer series with variation in PU/BA %

However, due to enhanced intraparticle secondary forces, probability of development of interparticle secondary forces was reduced; consequently, comparatively low viscosity and solid contents were observed here. Similarly the generation of small nano sized micelles was attributed to these intraparticle secondary forces in section 4.2.3. Table 4.15 reveals that solid contents of

78 different emulsions in this series were 35.5 % to 29.9 % and viscosity was 43.2 cps to 14.1 cps. These results are presented graphically in the Figures 4.17 and 4.18. In previous literature, Zhu et al. (2008) found solid contents and viscosity of different water-borne PUA latexes. They reported solid contents 24.3 % to 29.9 % and viscosity 17.3 cps to 34.0 cps.

Figure 4.18 Variation in solid contents (%) of PUA emulsions of AR-3- PCL copolymer series with variation in PU/BA %

4.3.4 Viscosity and solid contents of PUA emulsions of AL-1-PEG copolymer series

The PUA emulsions based on polyether polyol, PEG showed a comparatively higher solid contents and viscosity. It could be attributed to the hydrophobic nature of PU prepolymer. The viscosity and solid contents of AL-1-PEG copolymer series are presented in Table 4.16 and Figures 4.19 and 4.20, respectively. In this series first three emulsions AL-1.1-PEG, AL-1.2- PEG and AL-1.2-PEG with PU/BA 10/90, 20/80 and 30/70 %, respectively were stable, but the other emulsions with higher PU/BA % 40/60 and 50/50 were coagulated after preparation. Therefore, it was not possible to determine the viscosity of these coagulated emulsions; however, solid contents were determined gravimetrically and reported in Table 4.16. It was observed that the solid contents of emulsions in this series were decreased regularly from higher concentrations of BA to lower ones. The solid contents of emulsions were 45.48 % to 39.94 %. These findings 79 are comparable to the results reported by Šebenik et al. (2003). They prepared acrylic polyurethane hybrids by using PU dispersion and observed the solid contents of PUA hybrids 34.2 % to 49.9 %. According to the data given in Table 4.16 and Figure 4.20 the viscosity of emulsions was changing regularly. The PUA copolymer particles having PEG soft segment, swelled and inter-particle hydrophobic interactions and entanglements resulted in resistance to flow.

Table 4.16 Sample code, composition, solid contents and viscosity of PUA emulsions AL-1- PEG copolymer series. Sample Solid Viscosity Sr. No. PU/BA (% ) Composition code contents (%) (cps) 1. AL-1.1-PEG 10/90 H12MDI:PCL:HEMA:BA 45.48 50.9 2. AL-1.2-PEG 20/80 H12MDI:PCL:HEMA:BA 44.54 35.5 3. AL-1.3-PEG 30/70 H12MDI:PCL:HEMA:BA 42.81 29 4. AL-1.4-PEG 40/60 H12MDI:PCL:HEMA:BA 41.89 ----- 5. AL-1.5-PEG 50/50 H12MDI:PCL:HEMA:BA 39.94 -----

Figure 4.19 Variation in viscosity (cps) of PUA emulsions of AL-1-PEG copolymer series with variation in PU/BA %

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Figure 4.20 Variation in solid contents (%) of PUA emulsions of AL-1- PEG copolymer series with variation in PU/BA %

4.3.5 Viscosity and solid contents of PUA emulsions of AL-2-PEG copolymer series

The AL-2-PEG copolymer series were prepared by using monomers IPDI, PEG, 2-HEMA and BA. The emulsions up to 30/70 % PU/BA were stable, while the next one with higher PU/BA % was coagulated just after preparation. Table 4.17 Sample code, composition, solid contents and viscosity of PUA emulsions of AL- 2-PEG copolymer series. Solid Viscosity Sr. No. Sample code PU/BA (% ) Composition contents (cps) (%) 1. AL-2.1-PEG 10/90 IPDI:PCL:HEMA:BA 46.44 71.4 2. AL-2.2-PEG 20/80 IPDI:PCL:HEMA:BA 46.2 64.2 3. AL-2.3-PEG 30/70 IPDI:PCL:HEMA:BA 41.62 45.9 4. AL-2.4-PEG 40/60 IPDI:PCL:HEMA:BA 30.53 ------

The viscosity of stable emulsions was measured and reported in Table 4.17. Graphically viscosity variation with the variation in PU/BA % can be seen in Figure 4.21. The viscosity was decreased from 71.4 cps to 45.9 cps with the decrease in BA concentration. This decrease in viscosity might be because of reduced inter chain interactions in polymeric chains due to decrease in solid contents of emulsions, thus destroying the associated structures and chain entanglements (Asif and Shi, 2004). The data presented in Table 4.17 and Figure 4.22 depicts 81 that solid contents of emulsions decreased gradually with decrease in concentration of BA. The solid contents measured gravimetrically were 46.44 % to 30.53 %. Šebenik et al. (2003) working on acrylic polyurethane hybrids reported results close to the findings here. They recorded solid contents of different acrylic polyurethane hybrids 34.2 % to 49.9 %.

Figure 4.21 Variation in viscosity (cps) of PUA emulsions of AL-2-PEG copolymer series with variation in PU/BA %

Figure 4.22 Variation in solid contents (%) of PUA emulsions of AL-2- PEG copolymer series with variation in PU/BA %

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4.3.6 Viscosity and solid contents of PUA emulsions of AR-3-PEG copolymer series

The emulsions of AR-3-PEG series showed comparatively higher viscosity and solid content. Due to flexibility of TDI based prepolymer secondary interactions and chain entanglements were enhanced (Asif et al., 2009). According to results reported in Table 4.18, solid contents and viscosity both were decreased with decrease in BA concentration. Table 4.18 Sample code, composition, solid contents and viscosity of PUA emulsions of AR- 3-PEG copolymer series. Solid Viscosity Sr. No. Sample code PU/BA (% ) Composition contents (%) (cps) 1. AR-3.1-PCL 10/90 TDI:PCL:HEMA:BA 44.39 96.3 2. AR-3.2-PCL 20/80 TDI:PCL:HEMA:BA 41.5 59.9 3. AR-3.3-PCL 30/70 TDI:PCL:HEMA:BA 40.0 56.5 4. AR-3.4-PCL 40/60 TDI:PCL:HEMA:BA 38.2 36.6 5. AR-3.5-PCL 50/50 TDI:PCL:HEMA:BA 35.49 42.0

Figure 4.23 Variation in viscosity (cps) of PUA emulsions of AR-3-PEG copolymer series with variation in PU/BA %

The solid contents were 44.39 % to 35.49 % while viscosity was 96.3 cps to 42.0 cps. The variations in viscosity and solid contents with the variation in PU/BA % are demonstrated in the Figures 4.23 and 4.24 respectively. With the decrease in BA concentration particle size was decreased thus interparticle interactions and entanglements were reduced. Consequently, a

83 gradual decrease in viscosity was observed here. These results are in agreement with the previous reported literature. Wang et al. (2006) synthesized aqueous polyurethane polytert- butylacrylate (PU/Pt-BA) hybrid dispersions and observed same decreasing viscosity trend along with the decrease in concentration of Pt-BA.

Figure 4.24 Variation in solid contents (%) of PUA emulsions of AR-3- PEG copolymer series with variation in PU/BA %

4.4 Chemical and water resistance of PUA copolymer emulsions

To evaluate the overall performance of the coatings, the coated films of PUA copolymer emulsions were subjected to different qualitative tests. The chemical and water resistance was evaluated according to ASTM D 1647-89. The specified panels coated with emulsions were immersed in 3 % (w/w) solutions of H2SO4 and NaOH for chemical resistance and in deionized water for water resistance. Experiments were carried out at ambient temperature, 25±2 oC. The results obtained from chemical and water resistance tests are categorized in three different tables on the basis of different diisocyanate used in preparation of PUA copolymers. The data given in Tables 4.19, 4.20 and 4.21 presents observations of PUA copolymer emulsions based on three different diisocyanates i.e. H12MDI, IPDI and TDI, respectively.

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Table 4.19 Chemical and water resistance of PUA copolymer emulsions based on Methylene bis (4-cyclohexylisocyanate) (H12MDI) PU/BA Resistance Sample code Composition (% ) Acid Base Water H12MDI:PCL: AL-1.1-PCL 10/90 Excellent v. good not visibly affected HEMA:BA H12MDI:PCL: AL-1.2-PCL 20/80 Excellent v. good Blooming disappear in 2 hrs. HEMA:BA H12MDI:PCL: AL-1.3-PCL 30/70 Excellent Good Blooming disappear in 2 hrs. HEMA:BA H12MDI:PCL: AL-1.4-PCL 40/60 Excellent Good Blooming disappear in 2 hrs. HEMA:BA H12MDI:PCL: AL-1.5-PCL 50/50 Excellent Good Blooming disappear in 2 hrs. HEMA:BA H12MDI:PCL: Blooming disappear in 20 AL-1.1- PEG 10/90 Excellent v. good HEMA:BA min. H12MDI:PCL: Blooming disappear in 20 AL-1.2- PEG 20/80 Excellent v. good HEMA:BA min. H12MDI:PCL: Blooming disappear in 20 AL-1.3- PEG 30/70 Excellent v. good HEMA:BA min. H12MDI:PCL: Blooming disappear in 20 AL-1.4- PEG 40/60 Excellent Good HEMA:BA min. H12MDI:PCL: Blooming disappear in 20 AL-1.5- PEG 50/50 Excellent Good HEMA:BA min.

These results demonstrate excellent acid and good to very good base resistance for all of the PUA emulsions. Also, for water resistance test of different emulsions blooming was disappeared in 20 min. or in 2 hrs showing appreciable results. Such enhanced chemical and water resistance was observed by some other researchers in the literature (Athawale and Kulkarni, 2009, Deka and Karak, 2009). Zhu et al. (2008) stated that pure PU films are of low water resistance, however here in this study improved water resistance might be accredited to combination of acrylates with PU chains. Also, urethane and urea linkages in PU backbone are vulnerable to alkaline media. But better chemical and water resistance of PUA copolymers emulsions, especially alkali resistance could be due to exceptional performance of acrylates in an alkaline environment (Athawale and Kulkarni, 2009). However these qualitative tests are unable to distinguish the role of different constitutive monomeric units.

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Table 4.20 Chemical and water resistance of PUA copolymer emulsions based on 1- Isocyanato-3-Isocyanatomethyl-3,5,5-Trimethylcyclohexane (IPDI) PU/BA Resistance Sample code Composition (% ) Acid Base Water IPDI:PCL: AL-2.1-PCL 10/90 excellent v. good Blooming disappear in 20 min. HEMA:BA IPDI:PCL: AL-2.2-PCL 20/80 excellent v. good Blooming disappear in 20 min. HEMA:BA IPDI:PCL: AL-2.3-PCL 30/70 excellent v. good Blooming disappear in 20 min. HEMA:BA IPDI:PCL: AL-2.4-PCL 40/60 excellent v. good Blooming disappear in 20 min. HEMA:BA IPDI:PCL: AL-2.5-PCL 50/50 excellent v. good Blooming disappear in 2 hrs. HEMA:BA IPDI:PCL: AL-2.1- PEG 10/90 excellent v. good Blooming disappear in 20 min. HEMA:BA IPDI:PCL: AL-2.2- PEG 20/80 excellent v. good Blooming disappear in 20 min. HEMA:BA IPDI:PCL: AL-2.3- PEG 30/70 excellent v. good Blooming disappear in 20 min. HEMA:BA

Table 4.21 Chemical and water resistance of PUA copolymer emulsions based on 2,4/2,6- diisocyanato-1-methyl-benzene (TDI) PU/BA Resistance Sample code Composition (% ) Acid Base Water TDI:PCL: AR-3.1-PCL 10/90 Excellent good Blooming disappear in 2 hrs. HEMA:BA TDI:PCL: AR-3.2-PCL 20/80 Excellent v. good Blooming disappear in 2 hrs. HEMA:BA TDI:PCL: AR-3.3-PCL 30/70 Excellent good Blooming disappear in 2 hrs. HEMA:BA TDI:PCL: AR-3.4-PCL 40/60 Excellent good Blooming disappear in 2 hrs. HEMA:BA TDI:PCL: AR-3.5-PCL 50/50 Excellent good not visibly affected HEMA:BA TDI:PCL: AR-3.1- PEG 10/90 Excellent v. good Blooming disappear in 20 min. HEMA:BA TDI:PCL: AR-3.2- PEG 20/80 Excellent v. good Blooming disappear in 20 min. HEMA:BA TDI:PCL: AR-3.3- PEG 30/70 v. good v. good Blooming disappear in 20 min. HEMA:BA TDI:PCL: AR-3.4- PEG 40/60 v. good v. good Blooming disappear in 20 min. HEMA:BA TDI:PCL: AR-3.5-PEG 50/50 Excellent v. good Blooming disappear in 20 min. HEMA:BA 86

4.5 Thermal analysis

4.5.1 Thermogravimetric analysis (TGA)

Thermal stability and decomposition of PUA copolymers was carried out by thermogravimetric analysis (TGA). To investigate thermal behavior of final product a representative sample of PUA copolymer of each series was selected and placed in oven to completely remove the traces of solvent. Subsequently, TGA of these samples was performed in a neutral environment i.e. N2 environment, with temperature scan from 25 oC to 600 oC with the ramp of 10 oC/ min. In order to compare thermal response of PUA copolymers of different series TIDT, T50%, Tmax, and residue at Tend were recorded and presented in Table 4.22.

Table 4.22 Labeling, composition, TIDT, T50%, Tmax, and residue at Tend of representative PUA copolymers a b c Residue at Sample code Composition TIDT T50% Tmax d Tend (%)

AL-1.2-PCL H12MDI:PCL:HEMA:BA 245.63 416.60 425.35 8.27

AL-1.2-PEG H12MDI:PEG:HEMA:BA 233.92 391.99 395.19 9.50 AL-2.2-PCL IPDI:PCL:HEMA:BA 239.26 379.77 382.12 7.82 AL-2.2-PEG IPDI:PEG:HEMA:BA 236.38 394.76 398.68 5.23 AR-3.2-PCL TDI:PCL:HEMA:BA 240.24 381.82 386.82 2.79 AR-3.2-PEG TDI:PEG:HEMA:BA 260.31 413.30 413.40 7.515 a Initial decomposition temperature b Temperature at 50 % weight loss c Temperature at maximum rate of weight loss d Temperature at the end of degradation

The thermal degradation examination of polymers is required to determine the proper conditions for processing and manipulation of high-performance products that are stable. It also provides information about the presence of undesirable by-products, if any. Moreover, the TGA provides a simple method for accelerating the lifetime testing of polymers, so that these short-term experiments can be used to predict in-use lifetime. The thermal stability of a textile finish is vital for its long term use. It is generally stated that the urethane linkages are formed quite easily, and are less stable i.e. they are dissociated more easily as compared to those formed with more difficulty (Asif and Shi, 87

2004). However, the secondary interactions i.e. hydrogen bonding, polar-polar interactions etc. restrict the segmental motion and play important role in increasing the thermal stability. Therefore, it is likely that the PUA copolymers showed improved thermal stability because of enhanced secondary forces between different polymeric chains and groups of crosslinked polymers. Polyurethanes with different backbone structures have different thermal behaviours. Usually polyurethanes show two stage degradation in thermal analysis; the first stage and second stage owing to hard segment and soft segment decomposition, respectively (Asif and Shi, 2004, Chai et al., 2008; Deka and Karak, 2009). The TGA and DTG curves of PUA copolymers are shown in Figures 4.25 to 4.36. Here in these curves it can be observed that all copolymers exhibited just one stage decomposition with single Tmax. It might be attributed to the more uniform phase structure of crosslinked copolymers due to cross-linking reactions. Chai et al. (2008) studied the thermal behaviour of crosslinked PUA by TGA and concluded that two different stages of decomposition became closer to one another because of increased uniformity in phase structure. Likewise, a one stage degradation of PUA coatings during thermal analysis has also been observed by Wang et al. (2010). Therefore, it is proposed that one stage degradation observed in present study was likely due to the uniform phase structures of cross- linking copolymers.

The initial decomposition temperature (TIDT) of representative PUA copolymers is given in Table 4.22. It was recorded at 5 % weight loss of copolymer samples. This given data presents relatively higher thermal stability of PUA copolymers with aromatic diisocyanate (TDI). The AR-3.2-PEG and AR-3.2-PCL were degraded 5 % at 260.31 oC and 240.24 oC, respectively. The thermal stability of PUA increased with aromatic moieties, as they can withstand considerable amount of heat (Deka and Karak, 2009). The 5 % weight loss of IPDI and H12MDI based copolymers occurred at 233.92 oC to 245.63 oC. These results are quite compareable to recent findings where 5 % degradation of water-borne polyurethane acrylate was observed at 246.0 oC (Wang et al., 2010). Overall, PUA copolymers with polyester soft segment (PCL) showed higher

TIDT as compared to polyether (PEG) based copolymers. It could be due to higher chance of strong secondary forces between –CO and –NH groups in PCL based polymer backbone (Deka and Karak, 2009).

The T50% of different PUA copolymers presented in Table 4.22 were recorded at 50 % weight loss from TGA curves. The 50 % degradation of polyester (PCL) based PUA copolymers AL- 88

1.2-PCL, AL-2.2-PCL and AR-3.2-PCL was observed at 416.6 oC, 379.77 oC and 381.12 oC, respectively. While polyether (PEG) based copolymers AL-1.2-PEG, AL-2.2-PEG and AR-3.2- o o o PEG showed T50% at 391.99 C, 394.76 C and 414.30 C, respectively. All of the PUA copolymers that were synthesized by emulsion polymerization showed thermal stability to a great extent when compared with the previous results. Wang et al. (2010) synthesized multi- functional water-borne polyurethane acrylate nanocomposite coatings by introducing the acrylate groups into the end of the polyurethane main chains and tin oxide nano particles. They studied the thermal behaviour of these coatings and reported 50 % degradation at 302 oC to 324 oC, which is much lower as compared to T50% of different PUA copolymers observed in present study.

The temperature at maximum rate of weight loss (Tmax) of copolymers was detected from respective differential thermogravimetric (DTG) curves and presented in Table 4.22. The maximum rate of weight loss of polyester (PCL) based PUA copolymers AL-1.2-PCL, AL-2.2- PCL and AR-3.2-PCL was recorded at 425.35 oC, 382.12 oC and 386.82 oC, respectively. Whereas polyether (PEG) based copolymers AL-1.2-PEG, AL-2.2-PEG and AR-3.2-PEG o o o demonstrated Tmax at 395.19 C, 398.68 C and 413.40 C respectively. These results showed a clear improvement in thermal stability of PUA copolymers as compared to those reported in literature. Mishra et al. (2009) synthesized UV-curable hybrid coatings of hyperbranched polyurethane acrylate with ZnO. They evaluated thermal stability of non-hybrid PUA and hybrid coatings. Their findings showed improved thermal behaviour of PUA-ZnO hybrid coatings with o Tmax at 298.0 C. While non-hybrid, simple PUA coatings had maximum rate of weight loss at o 261.8 C. However, in present study all of the copolymers had shown much higher Tmax, 382.12 oC to 425.35 oC, demonstrating superior thermal stability. Also, Wang et al. (2010) reported improved thermal stability of water-borne PUA nano composites with maximum rate of weight loss at 320 oC, which is much lower to what we have evaluated in this study. o o The highest T50% and Tmax at 416.60 C and 425.35 C were observed, respectively, when basic monomers in PU chains were H12MDI and PCL; it might be due to symmetric structure of diisocyanate along with strong secondary interactions of polar groups in the crosslinked copolymer, which hamper the segmental motion. The AR-3.2-PEG also showed relatively higher o o T50% and Tmax at 414.30 C and 413.40 C, correspondingly. It can be attributed to aromatic

89 nature of diisocyanate developing interactions with PEG; which is a small relatively less polar structure of soft segment (Deka and Karak, 2009).

Figure 4.25 TGA curve (10oC/min) of a representative PUA copolymer of AL-1-PCL copolymer series based on H12MDI, PCL, 2-HEMA and BA

Figure 4.26 DTG curve (10oC/min) of a representative PUA copolymer of AL-1-PCL copolymer series based on H12MDI, PCL, 2-HEMA and BA

During thermogravimetric analysis, PUA copolymers were completely degraded and converted to char at the end temperature i.e. 600 oC. The remaining weight % of different copolymer samples at Tend is reported in Table 4.22. These results revealed almost complete degradation of

90 copolymers. For all of the PUA copolymers remaining residue was very small i.e. < 10 %, that is comparable to the findings reported by Wang et al. (2010) for pure water-borne PUA coatings. From the thermal studies reported here it is concluded that the copolymerization of PU with acrylates had significantly improved the thermal stability of these copolymers. The observation of one stage degradation would be due to crosslinked structure of final copolymers.

Figure 4.27 TGA curve (10oC/min) of a representative PUA copolymer of AL-1-PEG copolymer series based on H12MDI, PEG, 2-HEMA and BA

Figure 4.28 DTG curve (10oC/min) of a representative PUA copolymer of AL-1-PEG copolymer series based on H12MDI, PEG, 2-HEMA and BA

91

Figure 4.29 TGA curve (10oC/min) of a representative PUA copolymer of AL-2-PCL copolymer series based on IPDI, PCL, 2-HEMA and BA

Figure 4.30 DTG curve (10oC/min) of a representative PUA copolymer of AL-2-PCL copolymer series based on IPDI, PCL, 2-HEMA and BA

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Figure 4.31 TGA curve (10oC/min) of a representative PUA copolymer of AL-2-PEG copolymer series based on IPDI, PEG, 2-HEMA and BA

Figure 4.32 DTG curve (10oC/min) of a representative PUA copolymer of AL-2-PEG copolymer series based on IPDI, PEG, 2-HEMA and BA

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Figure 4.33 TGA curve (10oC/min) of a representative PUA copolymer of AR-3-PCL copolymer series based on TDI, PCL, 2-HEMA and BA

Figure 4.34 DTG curve (10oC/min) of a representative PUA copolymer of AR-3-PCL copolymer series based on TDI, PCL, 2-HEMA and BA

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Figure 4.35 TGA curve (10oC/min) of a representative PUA copolymer of AR-3-PEG copolymer series based on TDI, PEG, 2-HEMA and BA

Figure 4.36 DTG curve (10oC/min) of a representative PUA copolymer of AR-3-PEG copolymer series based on TDI, PEG, 2-HEMA and BA

4.5.2 Differential scanning calorimetry (DSC) The thermal response of PUA copolymers in this work was measured using a NETSCH DSC 200 F3 Germany, instrument. For the study of thermal history by DSC, a single representative copolymer sample was selected from each series. In order to evaporate the solvent, the copolymer emulsions were dried in oven until constant weight was attained. Then these samples

95 were stored at room temperature before thermal analysis. Approximately 15-18 mg of sample was hermetically sealed in an aluminum pan and scanned under nitrogen purge at a rate of 10oC/min, from -60 oC to 250 oC. The glass transition temperatures (Tgs) were measured at the half width of the transitions after plotting tangents on the curve, while melting temperatures were recorded from the peak temperatures of observed endotherms. Usually, in DSC studies of polyurethanes, two Tgs are reported; one associated with the soft segment at relatively lower temperature, and the other due to hard segment at higher temperature. The immiscibility of segments can result in reduced Tg of the soft segment. However, segmental mixing can lead to an increment in the soft segment Tg. In case of strong segmental mixing, one can expect the Tg of copolymer in between the Tgs of the hard and soft segments. Similarly, in case of PUA copolymers cross-linking in end product may lead to mixed Tg. Here in this study, DCS curves of all of the PUA copolymers showed just one or two Tgs. It might be observed due to phase mixing in the structure of crosslinked copolymer (Chai et al., 2008). The DSC curve of AL-1.2-PCL copolymer is shown in Figure 4.37. There were two clear glass transitions temperatures (Tgs) in this curve; one at lower temperature i.e., -43.3 oC and the other o at 20.5 C. The lower glass transitions temperatures (Tg1) might be due to the collective micro- brownian segmental motion of soft segment of PU and cross-linked acrylates. While the other o glass transition temperature (Tg2) at 20.5 C could be a result of thermal reaction of hard segment. Since, the soft segment was at the center of PUA structure and at the two vinyl terminated ends, hard segment was cross-linked with acrylates. Hence, different polar groups could develop secondary interactions, leading to mutual thermal response of soft segment and acrylates. Previously, Chai et al. (2008) comparatively studied core-shell and crosslinked interpenetrating network structure polyurethane polyacrylate composite emulsions. Comparable to the observations found in this study, they experienced only two transitions for crosslinked PUA emulsions, one at lower and the other at higher temperature. The melting temperature (Tm) of copolymer was observed as an endotherm at 217.9 oC with a small shoulder peak at 228.0 oC. The change in enthalpy was very low as - 4.307 J/g. The DSC thermogram of AL-1.2-PEG copolymer is presented in Figure 4.38. The two separate Tgs could be seen at 14.3 oC and at 41.3 oC. During synthesis of PUA copolymers, the vinyl terminated PU prepolymer was copolymerized with acrylates. It could be expected that the soft segment was in the center while, the hard segment along with acrylates at the end of polymeric chains. Therefore, Tg1 might be 96 due to combined thermal response of phase mixed soft segment and acrylates in the cross-linked copolymer and Tg2 can be assigned to the segmental motions of hard segment of PU.

Figure 4.37 DSC thermogram (10oC/min) of a representative PUA copolymer of AL-1-PCL copolymer series based on H12MDI, PCL, 2-HEMA and BA

However, the difference of 27 oC between two Tgs suggested that there was partial phase mixing in microphase structure of copolymers. The melting temperature of copolymer (Tm) was observed in the form of two consecutive endotherms at 210.6 oC and at 230.4 oC.

Figure 4.38 DSC thermogram (10oC/min) of a representative PUA copolymer of AL-1-PEG copolymer series based on H12MDI, PEG, 2-HEMA and BA

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The partial phase mixing in polymeric structure might be responsible for this division of Tm into two endotherms. The Figure 4.39 demonstrates the DSC response of AL-2.2-PCL copolymer.

The two separate Tgs were observed in this figure, but not so distant from one another. The Tg1 o o appeared at -7.49 C and Tg2 at 11.0 C. In analogy to thermal response of the other PUA copolymers in this study, the Tg1 of this copolymer was expected at lower temperature due to flexible structure of PCL soft segment and crosslinked acrylates, the Tg2 was assigned to the hard segment of PU. These two close Tgs and an increment in Tg1 of PCL, pointed towards enhanced phase mixing in microphase structure of copolymer. This is probably due to the reason that soft and hard segments had undergone cross-linking reactions with the acrylates, leading to the increase of the degree of phase uniformity of the cross-linked PUA (Chai et al., 2008). The development of secondary interactions between different parts of polymer structure developed enhanced phase uniformity. For the melting of copolymer a single deep endotherm was observed at 237.40 oC.

Figure 4.39 DSC thermogram (10oC/min) of a representative PUA copolymer of AL-2-PCL copolymer series based on IPDI, PCL, 2-HEMA and BA

The DSC curve of AL-2.2-PEG copolymer is shown in Figure 4.40. In this case only one glass o transition temperature (Tg1) was observed at 15.7 C. Analogous observations were found by Šebenik et al. (2003) where a single Tg in DSC studies of hybrid acrylic polyurethane emulsions was observed. The appearance of one Tg instead of two independent Tgs for different phases was inevitable for homogeneous behavior of polymer at molecular level. The homogeneous structure

98 of copolymer might be attained in response to cross-linking and phase uniformity, developed due to secondary interactions between hard and soft segments of PU and acrylates. The relatively small structure of PEG could have facilitated in the establishment of this homogeneous structure.

IPDI could also have played a role by developing secondary interactions through three –CH3 groups at the carbon ring. This cross-linked copolymer was melted at 227 oC as indicated by a single endotherm at the end of DSC curve.

Figure 4.40 DSC thermogram (10oC/min) of a representative PUA copolymer of AL-2-PEG copolymer series based on IPDI, PEG, 2-HEMA and BA

The DSC thermogram of AR-3.2-PCL copolymer is given below in Figure 4.41. It showed two o o Tgs at -42.9 C and at 47.8 C. The Tg1 might be due to the mutual thermal response of soft segment (PCL) and acrylates. While, Tg2 could be assigned to micro brownian movements of hard segment of PU chains. The appearance of Tg2 at relatively higher temperature could be due to aromatic nature of the hard segment, as aromatic moieties can withstand higher temperatures (Deka and Karak, 2009). The melting of this aromatic PUA copolymer was observed as an endotherm at 216 oC. The DSC curve of AR-3.2-PEG copolymer is presented in Figure 4.42. In this thermogram only one Tg has manifested at 5.06 oC. The appearance of single Tg indicated phase mixing at molecular level in the copolymer. In a similar study, Wang et al. (2008) have reported worse phase separation between PEG and TDI in UV curable PUA. It is possible that in

99 their research work, phase mixing would be restricted due to availability of double bonds in UV curable system.

Figure 4.41 DSC thermogram (10oC/min) of a representative PUA copolymer of AR-3-PCL copolymer series based on TDI, PCL, 2-HEMA and BA

However, in current study, there was no free unsaturation at the end; therefore phase mixing could be plausible. The aromatic symmetric structure of TDI with one –CH3 group could have played an important role in phase mixing. The melting point of copolymer was detected by an endotherm at 234.8 oC.

Figure 4.42 DSC thermogram (10oC/min) of a representative PUA copolymer of AR-3-PEG copolymer series based on TDI, PEG, 2-HEMA and BA

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4.6 Textile performance of PUA copolymer series

The PU coatings are used in textile industry as finishing agents to improve the durability and fleeting look of the fabric (Zia et al., 2008). The PUA copolymer emulsions synthesized here in current research work were applied on textile fabrics and various parameters i.e. tear strength, rubbing fastness, washing fastness and light fastness, were evaluated according to standard textile methods. The utility functions which fabrics should fulfill first of all depend on their destination. The cotton fabrics have a very wide range of applications, starting from underwear and everyday clothing, through protective and work clothing, decorative and furniture fabrics, up to technical textiles. Such a wide range of application means that during their lifetime exposure, fabrics undergo actions from different forces and strains depending on their destination and working conditions. So, the textile fabrics, depending on their given intention, must fulfill many diverse specific requirements set down in special standards, which concern especially high mechanical strength and fastness properties. The quality parameters of fabrics like washing fastness, rubbing fastness and light fastness are indispensable to consider. Also, the tear strength of textile fabrics is one of the mechanical properties which most often decide their application in the routine life.

4.6.1 Tear strength

Fabric utility parameters most often depend on its mechanical properties. One of the most impor- tant strength parameters is tear strength. The tear strength of woven cotton fabrics is an important performance property, although it depends on fabric utilization area most of the fabrics is expected to have high tear strength. The tear strength of coated textile fabrics was determined by trouser standard test method (ASTM D1424 / BS EN ISO 13937-2). In this method, the rectangular fabric specimen was cut in the centre of shorter edges to form trouser shaped legs of equal lengths. The legs of the trouser were supported between two clamping jaws and pulled in the direction of the cut to tear the fabric. The tear force measured is the force required to propagate a previously started single tear when the force is applied parallel to the cut and the fabric tears in the direction of the applied force. The tear force was calculated from the force peaks and directly displayed on the electronic recording system.

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In this current study, different PUA emulsions were applied on fabric samples at two different concentration levels i.e. 3 % and 5 %. The tear strength of all of the coated fabric samples and of untreated fabric sample was measured. In the Tables 4.23, 4.24 and 4.25, % improvement in warp and weft tear strength of coated fabric samples are displayed accordingly. Table 4.23 Labelling, emulsion concentration, warp and weft wise (%) improvement in tear strength of textile fabric coated with H12MDI, PCL/PEG, 2-HEMA and BA based PUA emulsions. Emulsion Warp Weft Emulsion Warp Weft Sample conc. (%) (%) (%) conc. (%) (%) (%)

AL-1.1-PCL 5 % 154.81 163.35 3 % 176.09 148.75

AL-1.2-PCL 5 % 139.84 176.10 3 % 149.54 168.86

AL-1.3-PCL 5 % 148.04 159.78 3 % 142.18 157.83

AL-1.4-PCL 5 % 131.12 140.64 3 % 121.42 132.75

AL-1.5-PCL 5 % 128.19 128.21 3 % 133.60 153.08

AL-1.1-PEG 5 % 139.17 135.78 3 % 148.19 153.94

AL-1.2-PEG 5 % 138.64 158.05 3 % 144.51 154.05

AL-1.3-PEG 5 % 142.63 147.24 3 % 131.12 140.54

AL-1.4-PEG 5 % 137.14 150.48 3 % 125.26 131.89

AL-1.5-PEG 5 % 129.92 140.00 3 % 128.79 152.32

According to the results presented in the above Table 4.23, lower particle sized emulsions of AL- 1-PCL series i.e. AL-1.1-PCL, AL-1.2-PCL and AL-1.5-PCL, exhibited higher warp % improvement in tear strength at lower concentration of emulsions. However, in case of emulsions with relatively higher particle size i.e. AL-1.3-PCL and AL-1.4-PCL, both warp and weft % improvement in tear strength were decreased with lower level of emulsion concentration. It might be because of better dispersal and interaction of small nano particles of emulsions at the surface of fabrics. In AL-1-PEG series, warp and weft % improvement in tear strength decreased with increase in PU/BA ration in emulsions series. In this series, particle size was increased with increase in PU/BA ratio. Consequently, decrease in warp and weft % improvement could be

102 associated to the increase in particle size of PUA emulsions in this series. Also, AL-1-PEG series showed less warp % improvement and decreased weft % improvement in tear strength as compared to AL-1-PCL series. It could be attributed to the more polar groups of soft segment in AL-1-PCL series, which may perhaps develop more interactions with the polar surfaces of cotton fabrics. Table 4.24 Labeling, emulsion concentration, warp and weft wise (%) improvement in tear strength of textile fabric coated with IPDI, PCL/PEG, 2-HEMA and BA based PUA emulsions. Emulsion Warp Weft Emulsion Warp Sample Weft (%) conc. (%) (%) (%) conc. (%) (%)

AL-2.1-PCL 5 % 137.59 249.94 3 % 169.54 193.72

AL-2.2-PCL 5 % 157.44 155.89 3 % 129.47 186.59

AL-2.3-PCL 5 % 181.35 173.72 3 % 182.70 157.83

AL-2.4-PCL 5 % 161.80 161.29 3 % 163.98 136.21

AL-2.5-PCL 5 % 137.21 155.02 3 % 160.07 190.59

AL-2.1-PEG 5 % 156.84 144.97 3 % 140.00 151.02

AL-2.2-PEG 5 % 154.81 155.02 3 % 138.00 209.08

AL-2.3-PEG 5 % 119.84 143.24 3 % 137.44 124.00

AL-2.4-PEG 5 % 129.92 140.00 3 % 128.79 152.32

The results of warp and weft % improvement in tear strength of textile fabrics coated with IPDI, PCL/PEG, 2-HEMA and BA based PUA emulsions are shown in Table 4.24. In AL-2-PCL series, smallest particle size is of AL-2.5-PCL emulsion, which consequently showed best warp and weft % improvement at lower concentration i.e. 3 %, might be because of better adherence and penetration of small particles to the surface of fabric samples. While AL-2.4-PEG was coagulated just at the end of preparation, it showed comparatively less warp and weft % improvement. It could be due to reduced interaction of coagulated particles with the surface of fabric. The fabrics coated with PUA emulsions of AL-2-PCL series showed better warp and weft

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% improvement in tear strength as compared to AL-2-PEG series. It could be due to relatively more polar interaction of PCL based emulsions with the surface of cotton fabric. Table 4.25 Labeling, emulsion concentration, warp and weft wise (%) improvement in tear strength of textile fabric coated with TDI, PCL/PEG, 2-HEMA and BA based PUA emulsions. Emulsion Warp Weft Emulsion Warp Sample Weft (%) conc. (%) (%) (%) conc. (%) (%)

AR-3.1-PCL 5 % 159.32 154.37 3 % 151.42 179.13

AR-3.2-PCL 5 % 155.56 184.86 3 % 178.12 184.43

AR-3.3-PCL 5 % 121.65 179.78 3 % 138.79 150.91

AR-3.4-PCL 5 % 141.42 139.35 3 % 131.80 169.40

AR-3.5-PCL 5 % 127.51 154.05 3 % 119.77 149.72

AR-3.1-PEG 5 % 129.09 158.27 3 % 133.68 164.32

AR-3.2-PEG 5 % 169.02 170.81 3 % 154.96 171.24

AR-3.3-PEG 5 % 140.22 169.18 3 % 149.92 146.59

AR-3.4-PEG 5 % 117.44 149.08 3 % 132.33 183.89

AR-3.5-PEG 5 % 136.315 165.83 3 % 135.18 172.64

The results of warp and weft % improvement in tear strength of textile fabrics coated with TDI, PCL/PEG, 2-HEMA and BA based PUA emulsions are displayed in Table 4.25. The micelle size of AR-3.5-PCL emulsion was largest in AR-3-PCL series, which therefore, showed less warp and weft % improvement in tear strength of fabrics. It possibly could be due to reduced interaction of larger micelles with the surface of fabrics. Both of the TDI based series i.e. AR-3- PCL and AR-3-PEG showed comparable warp and weft % improvement. Moreover, aromatic diisocyanates are cheaper in market. Therefore, aromatic diisocyanate based PUA emulsions are recommended as textile finishing agents (Sultan et al., 2011b).

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4.6.2 Fastness properties of textile fabrics coated with PUA emulsions

Different fastness properties of fabrics are essential to evaluate, irrespective of their destination. The fastness of a material means the resistance of a material to change in any of its color characteristics, to transfer of its colorants to adjacent materials or both, as a result of the exposure of the material to any environment that might be encountered during the processing, testing, storage or use of the material. In this current research work, rubbing or crocking fastness, light fastness and washing fastness properties of textile fabrics coated with PUA emulsions were evaluated and compared with untreated one. The respective results are displayed in Table 4.26, 4.27 and 4.28. The rubbing fastness of fabric samples was determined by using a manual crock meter, Shirley development Ltd., Manchester, England. It was designed to test the discoloration extent of dry textile and leather after abrasion. The rubbing hammer of this crock meter was wrapped with dry or wet white cotton cloth, and then rubbed manually on the specimen clamped to the testing table ten times for 10 seconds. Two specimens were used for each fabric sample, one each for the dry and the wet tests. The cloth was then removed to evaluate the discolor level in comparison with a gray-scale. The rating on grey scale for staining was from 1-5 in ascending order of quality of this particular parameter. According to the results presented in Tables 4.26, 4.27 and 4.28 all of the PUA coated fabric samples showed best to excellent (4-5) rubbing fastness for dry specimens, and best (4) for wet specimens, comparable to the untreated fabric sample. These results predicted that application of PUA finishing coating has no side effect at the surface of fabric samples. There was no hazardous change during rubbing of the coated surfaces with white fabrics. The other fastness property, light fastness was assessed by light fastness tester, Shimadzu, Japan. The light source was Xenon-Arc lamp and time of exposure was 24 hrs., for all of the coated fabric samples as well as for untreated one. The light fastness is the degree to which a dye resists fading due to light exposure. All dyed fabrics have some susceptibility to light damage, simply because their strong colors are indications that they absorb the wavelengths that they don't reflect back. In fact light is a form of energy, and the energy that is absorbed by pigmented compounds may serve to degrade them or nearby molecules. This process of degradation can propagate and by-products can interact with the finishes coated on the surface of fabric. 105

Table 4.26 Labeling, emulsion concentration, rubbing fastness, washing fastness and light fastness of textile fabric coated with H12MDI, PCL/PEG, 2-HEMA and BA based PUA emulsions. Rubbing Rubbing Emul. Washing fastnessb Emul. Washing fastness fastnessa Light fastness Light Sample conc. c conc. fastness Change Staining fastness (%) dry wet Change in shade Staining on cotton(%) dry wet in shade on cotton AL-1.1-PCL 5 % 4-5 4 3 4-5 5-6 3 % 4-5 4 3-4 4-5 6 AL-1.2-PCL 5 % 4-5 4 3 4-5 6 3 % 4-5 4 3 4-5 6 AL-1.3-PCL 5 % 4-5 4 3-4 4-5 6 3 % 4-5 4 3-4 4-5 5-6 AL-1.4-PCL 5 % 4-5 4 3 4-5 5-6 3 % 4-5 4 3 4-5 5-6 AL-1.5-PCL 5 % 4-5 4 3 4-5 6 3 % 4-5 4 2-3 4-5 6 AL-1.1-PEG 5 % 4-5 4 3-4 4-5 5-6 3 % 4-5 4 3-4 4-5 5-6 AL-1.2-PEG 5 % 4-5 4 3-4 4-5 6 3 % 4-5 4 3 4-5 5-6 AL-1.3-PEG 5 % 4-5 4 3 4-5 6 3 % 4-5 4 3-4 4-5 6 AL-1.4-PEG 5 % 4-5 4 2-3 4-5 6 3 % 4-5 4 3 4-5 6 AL-1.5-PEG 5 % 4-5 4 2-3 4-5 6 3 % 4-5 4 2-3 4-5 6 a rubbing fastness of untreated fabric sample was, dry = 4-5 and wet = 4 b washing fastness of untreated fabric sample was, change in shade = 3-4 and staining on cotton = 4-5 c light fastness of untreated fabric sample was 5-6

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The samples of the textile fabrics were exposed to the light source, and the fastness was evaluated by the comparison of the any change of the exposed coated sample to the exposed untreated sample. The change in coated fabric samples was graded according to the standard rating i.e. 1-8, in ascending order of quality of light fastness. After 24 hrs., exposure of coated fabric samples in light fastness tester, they were taken out and any change was compared with the standard scale. The results are displayed in Tables 4.26, 4.27 and 4.28. It was found that there was no harmful consequence of PUA coatings at the surface of fabric samples. The standard grading for all of coated samples was 5-6 and 6 i.e. good to very good and very good comparable to the untreated one. The washing fastness of fabric samples was evaluated by using High Pressure Dying machine, Tsuji, MFG Co. Ltd., Osaka, Japan. The washing process was carried out at 60 oC for 30 min. with standard soda solution. This test was intended to notice any change at the surface of coated fabric samples during the removal of soil dust and/or any stains by treatment (washing) with an aqueous detergent solution and normally including subsequent rinsing, extracting and drying. During this test, change in shade of fabric samples and staining on the white cotton, stitched at on corner of samples were noticed according to the scale (1-5) i.e. poor to excellent performance. The respective results are displayed in Table 4.26, 4.27 and 4.28. Almost all of the coated fabrics showed good to very good i.e. 3-4 change in shade and very good to excellent i.e. 4-5 staining on cotton, pertaining no damage in color of samples by coatings. However, washing fastness of AL-1.4-PEG, AL-1.5-PEG and AL- 2.4-PEG was poor comparatively i.e. 2-3. It might be attributed to the larger particle size of these emulsions. So, their particles could not interact properly with fabric surface.

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Table 4.27 Labeling, emulsion concentration, rubbing fastness, washing fastness and light fastness of textile fabric coated with IPDI, PCL/PEG, 2-HEMA and BA based PUA emulsions. Rubbing Rubbing Washing fastnessb Emul. Washing fastness fastnessa Light fastness Light Sample Emul. conc. (%) c conc. Change Staining fastness Change Staining fastness dry Wet (%) dry wet in shade on cotton in shade on cotton AL-2.1-PCL 5 % 4-5 4 3-4 4-5 5-6 3 % 4-5 4 3-4 4-5 6 AL-2.2-PCL 5 % 4-5 4 3-4 4-5 6 3 % 4-5 4 3-4 4-5 6 AL-2.3-PCL 5 % 4-5 4 3 4-5 6 3 % 4-5 4 3 4-5 5-6 AL-2.4-PCL 5 % 4-5 4 3 4-5 5-6 3 % 4-5 4 3-4 4-5 5-6 AL-2.5-PCL 5 % 4-5 4 3-4 4-5 6 3 % 4-5 4 3-4 4-5 6 AL-2.1-PEG 5 % 4-5 4 3 4-5 5-6 3 % 4-5 4 3 4-5 5-6 AL-2.2-PEG 5 % 4-5 4 3-4 4-5 6 3 % 4-5 4 3-4 4-5 5-6 AL-2.3-PEG 5 % 4-5 4 3 4-5 6 3 % 4-5 4 3 4-5 6 AL-2.4-PEG 5 % 4-5 4 2-3 4-5 6 3 % 4-5 4 2 4-5 6 a rubbing fastness of untreated fabric sample was, dry = 4-5 and wet = 4 b washing fastness of untreated fabric sample was, change in shade = 3-4 and staining on cotton = 4-5 c light fastness of untreated fabric sample was 5-6

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Table 4.28 Labeling, emulsion concentration, rubbing fastness, washing fastness and light fastness of textile fabric coated with TDI, PCL/PEG, 2-HEMA and BA based PUA emulsions Rubbing Rubbing Emul. Washing fastnessb Emul. Washing fastness fastnessa Light fastness Light Sample conc. c conc. Change Staining fastness Change Staining fastness (%) Dry wet (%) Dry wet in shade on cotton in shade on cotton AR-3.1-PCL 5 % 4-5 4 3-4 4-5 5-6 3 % 4-5 4 3-4 4-5 6 AR-3.2-PCL 5 % 4-5 4 3 4-5 6 3 % 4-5 4 3 4-5 6 AR-3.3-PCL 5 % 4-5 4 3 4-5 6 3 % 4-5 4 3-4 4-5 5-6 AR-3.4-PCL 5 % 4-5 4 3-4 4-5 5-6 3 % 4-5 4 3 4-5 5-6 AR-3.5-PCL 5 % 4-5 4 3 4-5 6 3 % 4-5 4 3-4 4-5 6 AR-3.1-PEG 5 % 4-5 4 3-4 4-5 5-6 3 % 4-5 4 3 4-5 5-6 AR-3.2-PEG 5 % 4-5 4 3-4 4-5 6 3 % 4-5 4 3-4 4-5 5-6 AR-3.3-PEG 5 % 4-5 4 3-4 4-5 6 3 % 4-5 4 3 4-5 6 AR-3.4-PEG 5 % 4-5 4 3 4-5 6 3 % 4-5 4 3 4-5 6 AR-3.5-PEG 5 % 4-5 4 3 4-5 6 3 % 4-5 4 3 4-5 6 a rubbing fastness of untreated fabric sample was, dry = 4-5 and wet = 4 b washing fastness of untreated fabric sample was, change in shade = 3-4 and staining on cotton = 4-5 c light fastness of untreated fabric sample was 5-6

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Part II

In this part of research study, different PUA copolymer series were prepared by using TDI, IPDI, PMPGlu, 2-HEA and BA. The molar concentration of soft segment, PMPGlu was assorted progressively and its effect on stability of emulsions and on the surface of fabric was evaluated. Also effect of two different series, AR-0-PMPGlu and AL-0-PMPGlu, having aromatic and aliphatic diisocyanates, respectively, on the surface of fabric was investigated.

4.7 Chemical characterization of AR-0-PMPGlu copolymer series

All the emulsion samples were cured in the dry oven at 45 oC, for 48 h. These films were used for further analysis. FT-IR spectra of monomers toluene-2,4-diisocyanate (TDI) (Fig. 4.43 a), 2-methyl-1,3-propylene glutarate- diol terminated polyol (Fig. 4.43 b), isocyanate (NCO) terminated PU prepolymer obtained by the reaction of TDI and poly (2-methyl-1,3-propylene glutarate) diol terminated polyol (Fig. 4.43 c), 2-hydroxyethylacrylate (HEA) (Fig. 4.43 d), vinyl terminated PU prepolymer (Fig. 4.43 e), butyl acrylate (BA) (Fig. 4.43 f) and polyurethane acrylate copolymer (Fig. 4.43 g) are jointly presented in Figure 4.43 and discussed here in this section. The FT-IR spectra of toluene-2,4-diisocyanate (TDI) (Fig. 4.43 a) showed an intense peak at 2233.66 cm-1 due to characteristic isocyanate (–NCO) groups attached to the toluene-2,4- diisocyanate and a sharp peak at 1527 cm-1 , which is due to the C=C stretching of benzene ring. The observed peaks in the functional group region of FT-IR spectrum of poly (2-methyl- 1,3-propylene glutarate) diol terminated polyol (Fig. 4.43 b) were assigned as: 3506 cm-1 (OH -1 -1 stretching vibration); 2963 cm (asymmetric CH2 stretching); 2865 cm (symmetric CH2 stretching); 1726 cm-1 (C=O stretching). FT-IR spectrum of –NCO terminated PU prepolymer has also been presented in Figure 4.43 c. It is clearly observed that the signal for the OH groups disappeared and that of the intensity of isocyanate (–NCO) groups has been reduced to some extent resulting that OH groups have entirely reacted and a signal for –NH units appeared at 3239 cm-1 suggesting that –NCO terminated PU prepolymer had been formed (Fig. 4.43 c). The other observed peaks in the FT-IR spectrum of –NCO terminated PU -1 -1 prepolymer were assigned as: 2931 cm (CH asymmetric stretching of CH2); 2889 cm (CH -1 -1 symmetric stretching of CH2 groups); 2272 cm (isocyanate (–NCO) group); 1727 cm (C=O stretching of soft segment of poly (2-methyl-1,3-propylene glutarate) diol terminated polyol.

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Disappearance of intense peak at 2233 cm-1 (–NCO) and appearance of less intense peak at about 2272 cm-1 (–NCO), indicated that the –NCO group has reacted with OH groups of poly (2-methyl-1,3-propylene glutarate) diol terminated polyol and confirms that isocyanate terminated PU prepolymer has been formed. In the Figure 4.43 c, the –NCO terminated PU prepolymer exhibited the characteristic absorption peaks at about 810 cm-1 (C=C band), 1600 cm-1 (C=C bond), 1532 cm-1 (–NH bending and –CN stretch), 1720 cm-1 (C=O stretch) and 3339 cm-1 (–NH stretching) (Yaobin et al., 2006). The free ends of isocyanate groups were further reacted with hydroxy ethyl acrylates (HEA) (Wang et al., 2008). The observed peaks in the FT-IR spectrum of HEA (Fig. 4.43 d) were assigned as: 3486 cm-1 (OH stretching -1 -1 vibration); 2946 cm (asymmetric CH2 stretching); 2833 cm (symmetric CH2 stretching); 1723 cm-1 (C=O stretching); 1533 cm-1 (C=C stretching); 1135 cm-1 (C–O, C–C stretching). After the reaction of –NCO terminated PU prepolymer (Fig.4.43 c) with that HEA (Fig. 4.43 d), the vinyl terminated PU prepolymer was formed. FT-IR spectra of vinyl terminated PU prepolymer (Fig. 4.43 e) showed small stretching at 3330 cm-1 (–NH stretching) due to -1 formation of urethane linkages. The CH stretching of CH2 group was observed at 2931 cm . The FT-IR spectrum showed sharp peaks at 1727 cm-1 and 1530 cm-1 which is due to the C=O and C=C stretching of the synthesized material, respectively. It can be observed in the vinyl terminated PU prepolymer spectrum that –NCO peak has disappeared indicating the complete utilization of the –NCO group with that of HEA forming vinyl terminated PU prepolymer. Also, appearance of peaks at 809 cm-1 and at 1600 cm-1 delegates the incorporation of HEA in the PU backbone. The vinyl terminated PU prepolymer chain was further extended with the addition of butyl acrylate. The FT-IR spectrum of butyl acrylate (BA) is given in Figure 4.43 f. The observed peaks in the FT-IR spectrum of BA (Fig. 4.43 f) were assigned as: 2949 cm-1 -1 -1 (asymmetric CH2 stretching); 2830 cm (symmetric CH2 stretching); 1726 cm (C=O stretching); 1530 cm-1 (C=C stretching); 1131 cm-1 (C–O, C–C stretching). The Figure 4.43 g represents the complete synthesis of PU acrylate copolymer. It showed presence of –NH groups at about 3450 cm-1, carbonyl group at 1731 cm-1 and peaks at 2929 cm-1, 2870 cm-1 for CH anti-symmetric and symmetric stretching, respectively. The Figure 4.43 g provides clear information about the vibrational mode changes due to involvement of butyl acrylate to the polyurethane backbone during the polymerization reaction. In the FT-IR analysis obtained for the final PU acrylate sample, the disappearance of the –NCO peak at 2272 cm-1 and the appearance of –NH peak at 3393 cm-1 confirmed the completion of polymerization reaction.

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Figure 4.43 FT-IR spectrum of AR-0-PMPGlu copolymer series, a. TDI, b. PMPGlu polyol, c. PU prepolymer with free NCO groups, d. 2-HEA, e. vinyl terminated PU prepolymer, f. BA, g. PUA copolymer

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FT-IR spectrum of the final polyurethane acrylate copolymer supported the proposed structure of the final polymer. The observed peaks in the spectrum implied that the reaction was completed and the predesigned PU acrylate copolymer has formed.

4.8 Emulsion stability of the PUA emulsions of AR-0-PMPGlu copolymer series

The results regarding emulsion stability of the prepared polyurethane acrylate samples and the pilling evaluation of the printed satin treated fabrics are presented in Table 4.29. In five (5) sets of 30 experiments (e.g A1-F1, A2-F2, A3-F3, A4-F4, and A5-F5) the stability of the emulsions decreased by increasing the concentration of vinyl terminated polyurethane prepolymer or increased by decreasing the amount of butyl acrylates (BA). Furthermore, in five sets of 30 experiments when mole ratio of polyol was decreased, the stability of emulsions (for the period over one year) continually increases as mole ratio decreased from 2.0 moles to 1.9 and 1.8 moles, but when it further decreased to 1.7 and 1.6 moles, the emulsions were less stable comparatively. The resulting order of emulsion stability of the prepared samples have great influenced on the treated fabrics samples imparting high tensile strength and stretchability, excellent film forming characteristics, good body and handle for finished fabrics, excellent wash-fastness, resistant to dry cleaning, high crease-resistance and excellent pill resistance.

4.9 Textile performance of AR-0-PMPGlu copolymer series

All of the final copolymer emulsions of AR-0-PMPGlu series were applied on the surface of textile fabric and their effect was evaluated in the form of rating for pilling. The pills are localized minor disturbances randomly distributed on the surface, while protruding yarn, which are part of the fabric structure; appear to be periodical and associated only with the pattern of interlacing (weave) or interloping (knit). These give a very unsightly look to the garments. In the visual evaluation, observers intend to rate the pilling appearance of a fabric by comparing pill properties such as density, size and height, to those of the visual standards. (a): Pill density is the first impression that an observer probably will get when examining a pilled sample. The pill density is often estimated by the number of pills in a unit area. This definition is accurate only if pills are randomly or uniformly distributed over the area selected

113 for counting pills. When clumping occurs the result will substantially vary with the area. A more rational estimator of pill density can be constructed based on the distances of pills to their nearest neighbours. The nearest distance of two pills is the length between the two centres. (b): The average size of pills is another important factor influencing pilling appearance. Someone can locate and count the pill, and then calculate the following statistical data: mean, standard deviation, maximum, minimum and area percentage, which is equal to the ratio of the total area of pills to the image area. The size distribution curve can be calculated as well. (c): The contrast between a pill and its surrounding region reflects the height of the pill. In a gray-scale image, the contrast between two regions is measured by the difference in intensity. In order to make the rating results generated by the pilling evaluation system consistent with the visual standards, the ASTM photographic pilling standards is first analyzed using the system and the rating equations is built based on the measurements of pill properties of these photographs. Although the average size of pills has a decreasing trend when the pilling grade increases, there is no significant difference between grades 1 and 2. This is because pills are worn off as their sizes increase to a certain level. Hence, the average pill size alone is not sufficient for rating pilled samples. The density and % area of pills show relatively coherent decreases with the pilling grade, though the relationships are non-linear The results presented in Table 4.29 shows clear separation lines among the five pilling propensity groups and a progressive trend between the no pilling (rating 5) and the most severe pilling (rating 1) samples. The results in Table 4.29 show that the 32 pilling samples (30 experimental samples and 2 standard samples) in each standard test set are successfully classified into five pilling grades. Pilling evaluation results of 32 samples (A1 to F1, A2 to F2, A3 to F3, A4 to F4, A5 to F5, S1 and S2) showed that pilling rating improved by decreasing the amount of butyl acrylates (BA) and or by increasing the percentage of vinyl terminated PU prepolymer and vice versa. Furthermore, in all sets of 30 experiments and two standard samples when mole ratio of poly (2-methyl-1,3-propylene glutarate) diol terminated polyol is decreased, the pilling rating continually improved as mole ratio decreased from 2.0 moles to 1.6 moles. It can be observed that all sets of experiment have shown comparatively good results as compared to standard sample available in the market. In comparison to all the 5 sets, the samples (A5 to F5) have shown excellent results. This behaviour may be attributed to the good emulsion stability and computability of the copolymerized samples.

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Table 4.29 Formulations of polyurethane acrylate emulsions, pilling evaluation and emulsion stability ratings of coated textile fabrics

Composition of PUA emulsion Sr. Pilling Emul. Sr. Composition of PUA emulsion Pilling Emul. a b c d e a b c d e No. Pylol TDI HEA VTPU BuA ratef stability No. Pylol TDI HEA VTPU BuA ratef stability (mole) (mole) (mole) (%) (%) (mole) (mole) (mole) (%) (%) 1 2 3 2 5 95 3 A1 16 1.8 3 2 20 80 3/4 D3 2 2 3 2 10 90 3 B1 17 1.8 3 2 25 75 3/4 E3 3 2 3 2 15 85 3 C1 18 1.8 3 2 30 70 4 F3 4 2 3 2 20 80 3/4 D1 19 1.7 3 2 5 95 3 A4 5 2 3 2 25 75 3/4 E1 20 1.7 3 2 10 90 3 B4 6 2 3 2 30 70 3/4 F1 21 1.7 3 2 15 85 3/4 C4 7 1.9 3 2 5 95 3 A2 22 1.7 3 2 20 80 3/4 D4 8 1.9 3 2 10 90 3 B2 23 1.7 3 2 25 75 4 E4 9 1.9 3 2 15 85 3 C2 24 1.7 3 2 30 70 4 F4 10 1.9 3 2 20 80 3/4 D2 25 1.6 3 2 5 95 3 A5 11 1.9 3 2 25 75 3/4 E2 26 1.6 3 2 10 90 3/4 B5 12 1.9 3 2 30 70 3/4 F2 27 1.6 3 2 15 85 3/4 C5 13 1.8 3 2 5 95 3 A3 28 1.6 3 2 20 80 4 D5 14 1.8 3 2 10 90 3 B3 29 1.6 3 2 25 75 4 E5 15 1.8 3 2 15 85 3/4 C3 30 1.6 3 2 30 70 4 F5

31 g EFD commercial standard sample no. 1 3 S1 32 h SE commercial standard sample no. 2 3 S2

a Poly (2-methyl-1,3-propylene glutarate) diol terminated, b Toluene-2,4-diisocyanate (TDI), c 2-hydroxyethylacrylate (HEA), d Vinyl terminated polyurethane prepolymer, e Butyl acrylate (BA), f Pilling of untreated fabrics=2, g Commercial standard sample No.1 (EFD), h Commercial standard sample No.2 (SE)

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4.10 Chemical characterization of AL-0-PMPGlu copolymer series

For comparative studies of synthesized PUA copolymers with varying diisocyanate structure, the FT-IR spectra of polyurethane acrylate copolymers with TDI (PUAC-1) and with IPDI (PUAC-2) are presented in Figures 4.44 & 4.45 respectively. FT-IR spectra of monomers, intermediates and final TDI based copolymer PUAC-1 have discussed in previous section 4.7. However, spectral detail of monomers and final copolymer (PUAC-2) of AL-0-PMPGlu series will be discussed here. FT-IR spectra of isophorone diisocyanate (IPDI) (Fig. 4.45 a) showed an intense peak at 2233.66 cm-1 due to characteristic isocyanate (–NCO) groups attached to the isophorone diisocyanate (IPDI). Also it showed sharp peak at 2940 cm-1, which is due to the CH stretching of IPDI. The observed peaks in the functional group region of FT-IR spectrum of poly (2-methyl-1,3- propylene glutarate) diol terminated polyol (Fig. 4.45 b) were assigned -1 -1 as: 3502 cm (OH stretching vibration); 2959 cm (CH asymmetric stretching of CH2); 2867 -1 -1 cm (CH symmetric stretching of CH2 groups); 1724 cm (C=O stretching of soft segment of poly (2-methyl-1,3-propylene glutarate) diol terminated polyol). The IPDI and poly (2- methyl-1, 3-propylene glutarate) diol were reacted to prepare isocyanate (–NCO) terminated PU prepolymer which was further reacted with hydroxy ethyl acrylates (HEA) (Sultan et al., 2011a). The hydroxy ethyl acrylate (HEA) showed a very broad peak at 3486 cm-1 corresponding to OH stretching vibration. The other peaks observed in the FT-IR spectrum of -1 -1 HEA (Fig. 4.45 c) were assigned as: 2946 cm (asymmetric CH2 stretching); 2833 cm -1 -1 (symmetric CH2 stretching); 1723 cm (C=O stretching); 1533 cm (C=C stretching); 1135 cm-1 (C–O, C–C stretching). After the reaction of –NCO terminated PU prepolymer with that HEA; the vinyl terminated PU prepolymer was formed. The detailed FT-IR spectrum of vinyl terminated PU polymer has discussed in previous section 4.7 (Sultan et al., 2011a). The resulted vinyl terminated PU prepolymer was further extended with the addition of butyl acrylate. The FT-IR spectrum of butyl acrylate (BA) is given in Figure 4.45 d. The observed -1 peaks in the FT-IR spectrum of BA were assigned as: 2950 cm (asymmetric CH2 stretching); -1 -1 -1 2836 cm (symmetric CH2 stretching); 1729 cm (C=O stretching); 1533 cm (C=C stretching); 1134 cm-1 (C–O, C–C stretching). The Figure 4.45 e represents the completion of the synthesis of PU acrylate copolymers (PUAC-2). It shows presence of –NH groups at

116 about 3452 cm-1, carbonyl group at 1733 cm-1 and peaks at 2932 cm-1, 2872cm-1 for CH asymmetric and symmetric stretching, respectively (Yaobin et al., 2006). The FT-IR spectra obtained for the final PU acrylate sample (PUAC-1 and PUAC-2) confirmed the completion of polymerization reaction due to the disappearance of the –NCO peak at 2269 cm-1 and the appearance of –NH peak at 3387 cm-1. FT-IR spectrum of the final polyurethane acrylate copolymers supported the proposed structure of the final copolymer. The observed peaks in the spectrum implied that the reaction was completed and the predesigned PUA copolymer has shaped successfully.

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Figure 4.44 FT-IR spectra of AR-0-PMPGlu copolymer series, a. TDI, b. PMPGlu polyol, c. 2-HEA, d. BA, e. TDI based polyurethane acrylate copolymers (PUAC-1)

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Figure 4.45 FT-IR spectra of AL-0-PMPGlu copolymer series, a. IPDI, b. PMPGlu polyol, c. 2-HEA, d. BA, e. IPDI based polyurethane acrylate copolymers (PUAC-2).

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4.11 Physical characterization of AR-0-PMPGlu and AL-0-PMPGlu copolymer series

Physical parameters such as solid contents (%), emulsion stability, emulsion appearance, tackiness and film appearance of polyurethane acrylate copolymers (PUA's) are reported in Table 4.30. These characteristics are important and helpful for further use of emulsions in various applications (Athawale and Kulkarni 2009). Solid contents of the synthesized material are in the range of 35- 40 % (Huybrechts, et al., 2000).The reported results in Table 4.30 emphasis that dry weight contents of aromatic based PU acrylate copolymers (PUAC-1) is lesser as compared to the cyclo-aliphatic based (PUAC-2), moreover the emulsion stability of PUAC-2 (aliphatic based PU acrylate copolymer) is more pronounced which represents the better shelf life of these products. It is worthwhile mentioning that high solid contents reduce the shipping and storage costs due to the lower water content, allow increased productivity of plant equipment, have a short drying time and an adjustable film thickness in fewer passes. Emulsion appearance was almost same in all the studied samples, but when films were formed by dry heating, PUA emulsions containing TDI (PUAC-1) in backbone gave yellowish tint but the samples containing IPDI based emulsion films appeared transparent white. The yellowing of the aromatic diisocyanates (TDI) based polyurethane on exposure to light or heating has already reported by other researcher (David & Steve, 2002). Regarding tackiness of the samples IPDI based films are tack free whereas TDI based films have shown slight tackiness. The tack coat is a light coat that is applied to the surface to promote adhesion of successive coats. This coat covers the surface but does not fully wet out the substrate as the coating will have a light, uneven and transparent appearance. Table 4.30 Physical characteristics of representative PUA samples of AR-0-PMPGlu and AL-0-PMPGlu copolymer series Sample Solid Emulsion Emulsion Tackiness Film Code contents (%) stability appearance appearance PUAC-1a 35.32 <1 year white milky slight tacky yellowish smooth PUAC-2 b 38.28 >1 year white milky Tack free whitish smooth a Toluene-2,4-diisocyanate (TDI) based polyurethane acrylate copolymers b Isophorone diisocyanate (IPDI) based polyurethane acrylate copolymers

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4.12 Chemical resistance of AR-0-PMPGlu and AL-0-PMPGlu copolymer series

To evaluate the overall performance of coatings, cured films were subjected to acid and base solutions (Athawale and Kulkarni, 2009). From the data displayed in Table 4.31, it is obvious that chemical resistance shown by both types of PUA copolymers (PUAC-1 & PUAC-2) is same, excellent to acid environment and very good to basic solutions. Acid solutions were transparent till the third day of examination whereas basic solutions became slightly hazy from the very first day, it may be due to the action of alkali on urea bonds. However, this remarkable chemical resistance of PUA copolymers is in agreement with the observation of Athawale and Kulkarni (2009). Table 4.31 Chemical resistance of cured films of representative PUA samples of AR-0- PMPGlu and AL-0-PMPGlu copolymer series Chemical resistance Sample 1st day 2nd day 3rd day code Acid Base Acid Base Acid Base PUAC-1a Excellent Very good Excellent Very good Excellent Very good PUAC-2 b Excellent Very good Excellent Very good Excellent Very good a Toluene-2,4-diisocyanate (TDI) based polyurethane acrylate copolymers b Isophorone diisocyanate (IPDI) based polyurethane acrylate copolymers

4.13 Textile performance of AR-0-PMPGlu and AL-0-PMPGlu copolymer series

PU coatings are used in textile industry as finishing agents to improve the durability and fleeting look of the fabric (Zia et al., 2008). The results presented in Table 4.32, illustrate that fabric samples coated with PUA copolymers have shown more pronounced effects than untreated fabrics samples. The treated samples (with PUAC-1 & PUAC-2) were cured in two different ways i.e., vacuum cured and dry heating oven cured. According to the results, the vacuum cured samples have shown some better results as compared to the dry heating oven samples. For curing purpose the vacuum cured is preferred and recommended. In comparison of both the samples i.e., PUAC-1 & PUAC-2, the PUAC-1 has more prominent effect as finishing agent. Furthermore aromatic diisocyanate (TDI) is much cheaper so its use in textiles is advantageous economically also.

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Table 4.32 Abrasion test results of representative PUA samples of AR-0-PMPGlu and AL-0-PMPGlu copolymer series (vacuum and dry heating oven cured) Vacuum cured Dry heating oven cured Sample Shade Texture Shade Texture code Rating Rating change condition change condition No thread No thread PUAC-1a Slight 4 Poor 2-3 was broken was broken No thread No thread PUAC-2 b Noticeable 3 Noticeable 3 was broken was broken Uncoated Few thread Few thread Very poor 1-2 Very poor 1-2 fabrics was broken was broken a Toluene-2,4-diisocyanate (TDI) based polyurethane acrylate copolymers b Isophorone diisocyanate (IPDI) based polyurethane acrylate copolymers

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Summary

Polymers as a gift of nature are with us since the emergence of life on this universe, but man realized it much later. During the growing age of polymers, before the mid of 20th century polyurethanes (PU) were discovered by Otto Bayer and co-workers as an exclusive class of synthetic polymers with wide variety of applications. Applications of polyurethane are so wide spread because their properties can be readily tailored by the variation of their components. The urethane linkage is formed by the reaction of an isocyanate group of one reactant with the alcoholic group of another component. Furthermore, water-borne polyurethanes (WPU) are introduced as environment-friendly materials with good adhesion, elasticity, and chemical and solvent resistance. These are non-toxic and non-flammable materials. These WPU materials have been extensively applied in adhesives, coatings, surface finishing, paper and textile industries. The WPU technology is now growing at a prompt rate and is a very common practice in the industry. To take benefit of PU film-forming properties, a combination with a low cost material is now a common routine in the coating market, leading to new different and low cost products. One of the most popular second components is the acrylic moiety. Acrylic polymers are known to have superior water resistance, wearing resistance, adjustable mechanical properties and low cost, though they have low solvent and abrasion resistances. Combination of polyurethane with acrylics is expected to be valuable to increase the performances of the resulting materials. Polyurethane acrylates (PUA) are comb- like materials which can potentially merge the high abrasion, resistance, toughness, tear strength, chemical and solvent resistance, and good low temperature properties of polyurethanes with the good optical properties, water resistance, wearing resistance and weather ability of the acrylates. This dissertation was designed to synthesize and characterize the PUA copolymers containing different diisocyanates and polyols in different proportions with butyl acrylate. Therefore, synthesis of a series of PUA copolymers was carried out. The reaction of one equivalent of polyol with three equivalents of isocyanate led to the –NCO terminated PU prepolymer, which was further extended with 2 equivalents of hydroxy acrylate in order to incorporate unsaturations at the free ends of PU chains. The last step was copolymerization of vinyl terminated PU prepolymer with BA through emulsion polymerization. The whole work was completed in two parts of study; part I and II. The part I was performed at Iran Polymer and

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Petrochemical Institute, while the part II was carried out at Physical Chemistry Laboratory, Department of Chemistry and Biochemistry, University of Agriculture, Faisalabad. To establish the chemistry of synthesized PUA copolymers, different monomers, intermediates and final products were analyzed by FT-IR. The thermal history and degradation was studied by DSC and TGA, respectively. The particle size and poly dispersity index (PDI) of PUA copolymer emulsions were measured by dynamic light scattering apparatus. The viscosity and solid contents of PUA emulsions were measured. Qualitatively chemical and water resistance was evaluated according to ASTM D 1647-89. All of the PUA emulsions were applied on textile fabric and their textile performance was evaluated accordingly. The fabric was characterized according to ASTMD-3775. Other quality parameters like washing fastness, rubbing fastness, light fastness, abrasion resistance, pilling and tear strength were assessed according to AATCC 61-2003, 8-2005, 16-2004, ASTMD- 4966, ASTM D-3514-02 and ASTM D1424 / BS EN ISO 13937-2, respectively. Fairly stable nano sized emulsions of PUA were prepared. The FT-IR spectral analysis inferred that the reaction was carried out step wise and pre-designed PUA copolymers were synthesized effectively according to proposed reaction scheme. The thermal history and degradation study proved enhanced phase mixing and thermal stability of final products. The viscosity and solid contents of emulsions in different series were decreased progressively with the increase in PU/BA ratio. Also, chemical and water resistance was improved reasonably by the assimilation of acrylates in PU backbone. Textile performance of coated cotton-satin fabric samples was evaluated. It was demonstrated that abrasion resistance, pilling and tear strength of coated fabric samples were superior as compared to the untreated samples. However, fastness properties were just comparable to the blank samples, without any side effect. Hence, the application of PUA copolymers as finishing agent in textile could be recommended. All of the work presented in part II of this dissertation has published in an international journal “Carbohydrate Polymers” in 2011, and attached in appendix 1 and 2.

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