DOCSLIB.ORG

1.1 Basic Polymer Chemistry 1.2 Polymer Nomenclature 1.3 Polymer

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

1.1 Basic Polymer Chemistry 1.2 Polymer Nomenclature Polymers are the largest class of soft materials: over Polymer = 100 billion pounds of polymers made in US each year Monomer = Classification systems Polymer = Typical physical state? Mechanisms of chain growth Oligomer = Typical physical state? Polymerization = 1.3 Polymer Synthesis 1.4 Chain Growth Polymerization Two synthetic methods Addition polymerization Chain growth/addition polymerization One molecule adds to another with no net loss of atoms (high atom economy) Individual steps are typically rapid (msec, sec) Discrete steps Step growth polymerization Propagation rate >> termination rate What happens if the reaction runs longer? Do the chains get longer? Do you just get more chains? 1 1.5 Chain Growth Polymerization 1.6 Monomers for Chain Growth Addition polymerization Polymers form by… What’s in the polymerization mixture? Defining features Useful monomers for chain growth CH3 Cl CH2 CH CH CH Monomer Polymer H2C H2C H2C H2C ethylenepropylene styrene vinyl chloride nCH2 CH (CH2 CH)n X X O N X X C O O-CH3 CH2 O CH3 C HC C nCH2 CH (CH2 CH O)n CH C CH CH CH O H2C H2C 3 H2C H2C vinyl acetate methyl methacrylate butadiene acrylonitrile 1.7 Chain Growth Polymerization 2.1 Radical Polymerization Mechanisms to link monomers together Three steps to radical polymerization Radical Initiation Cationic (1) RO OR 2RO Anionic Transition metal catalysis (2) RO + H2C CH RO CH2 CH R R Propagation RO CH2 CH + H2C CH RO CH2 CH CH2 CH R R R R Termination 2 2.2 Radical Polymerization 2.3 Radical Polymerization Initiation Propagation Termination Radical Coupling polystyrene RO CH RO CH CH RO CH CH H2C CH2 H2C CH2 CH2 styrene Head attacks the tail of the next monomer What defines the “head”? Why would RO• attack the tail preferentially? Disproportionation (H abstraction) Initiation Propagation Cl Cl Cl Cl Cl RO CH RO CH CH RO CH CH polyvinylchloride H2C CH2 H2C CH2 CH2 vinyl chloride Propagation continues until … 2.4 Radical Polymerization 2.5 Radical Polymerization Chain transfer Another “termination” mechanism “back-biting” CH CH2 2 C H CH CH 4 9 CH CH2 2 CH2 CH2 CH CH2 CH2 H CH2 CH2 CH2 CH3 This is a prominent type of branch. Why would this be so? 3 2.6 Radical Polymerization 2.7 Radical Polymerization Another termination process (chloroalkanes) Monomers for radical polymerization RO (CH CH) CH CH Cl RO (CH2 CH)n CH2 CH + CCl4 2 n 2 F Cl Cl R R R R CH C + CCl3 2 F C CH F Cl H2C C H2C H2C CCl3 + CH2 CH Cl3CCH2 CH R R ethylene F 1,1-dichloroethylene vinylchloride 1,1,2,2-tetrafluoroethylene N CH2 O OCH3 HC C C C CH CH CH CH3 H C H2C H2C 2 H2C acrylonitrile 1,3-butadiene styrene methylmethacrylate 2.8 Radical Diene Polymerization 2.9 Radical Polymerization Reaction: Accounts for about ½ of all commercial polymerization nCH CH CH CH (CH CH CH CH ) 2 2 2 2 n What polymer structure forms when propylene is 1,3-butadiene polybutadiene subjected to a radical process? Mechanism: (1) ROOR 2RO (2) RO + CH2 CH CH CH2 RO CH2 CH CH CH2 Ethylene forms high molecular weight polymer but only under extreme conditions – why? (3) RO CH2 CH CH CH2 +CH2 CH CH CH2 RO CH2 CH CH CH2 CH2 CH CH CH2 Product is highly branched (where do the branches then (3), (3), (3), etc. come from?) Is it possible to make linear PE? 4 3.1 Cationic Polymerization 3.2 Anionic Polymerization Initiating and propagating species are cations Initiator and propagating species are anions Monomer attributes? Cationic polymerization of isobutene (2-methylpropene) Initiation Propagation Initiation Propagation CH3 CH3 CH3 H CH polystyrene C CH3 H C CH3 C 3 R CH R CH CH R CH CH H2C CH2 H2C CH CH Chain H2C 2 H2C 2 CH2 styrene isobutene or isobutylene titibtermination by loss of H+ CN CN CN CN CN Propagation What forms? R R CH R CH CH CH CH polyacrylonitrile CH3 CH3 H C H3C CH3 H2C CH2 2 CH2 CH2 polyisobutylene H C C CH3 C CH3 acrylonitrile H C CH2 CH2 2 3.3 Anionic Polymerization 3.4 Living Polymerization Monomer attributes? What’s a “living polymer”? Other example of monomers? Chain termination H O R CH CH CH 2 R CH CH CH + OH H CH2 CH2 n CH2 CH2 CH2 n CH2 polystyrene 5 4.1 Copolymers 4.2 Copolymers Random copolymers ABS = acrylonitrile-butadiene-styrene terpolymer CH2 CH + CH2 CH CH CH2 +CH2 CH CN SBR (styrene-butadiene rubber) CH2 CH CH2 CH CH CH2 CH2 CH nCH2 CH CN + > nCH2 CH CH CH2 Control the amount of each monomer that ends up CH CH CH CH CH CH CH CH CH CH 2 2 2 2 2 in the polymer? 4.3 Copolymers 4.4 Block Copolymers Block copolymers Polystyrene MhiMechanism an d process Polybutadiene Polybutadiene framework held together (cross-linked) by clusters of polystyrene Styrene-butadiene block copolymer SSSSSBBBSSSSSBB 6 4.5 Copolymers 5.1 Metal Catalyzed Polymerization Graft copolymers Coordination and Insertion M = Cr, Ti, Zr, Hf, V, Fe, Co, Ni, Pd, Cu Styrene-butadiene graft copolymer H2C Styrene polymerization off polybutadiene backbone CH2 L L L CH2CH3 CH2CH3 CH2 CH CH CH CH2 CH CH CH CH2 CH CH CH2 CH2CH3 M M M CH CH CH2 CH 2 2 C 2 CH2 C L L L H2 CH CH H2 H2C CH2 CH2 CH CH Could you graft polybutadiene off a polystyrene backbone? 5.2 Ziegler-Natta Catalysis 5.3 Ziegler-Natta Catalysis Chain Growth – Polyethylene (Polyethene) Chain Growth – Polypropylene (Polypropene) H2C H2C Cl Cl CH2 Cl CH3 CH2CH3 CH2CH3 Cl Cl C CH2CH3 Cl H CH2CH3 CH2CH3 Ti Ti Ti CH2CH3 CH2 CH Ti Ti Ti C 2 CH CH2 C H CH Cl Cl Cl H2 C H2 C C CH3 H C Cl Cl Cl H2 2 CH3 H2 CH3 H2C H C H2 2 CH2CH3 H H2C CH2CH3 C H C 2 Cl C 2 C H C C H Cl Cl CH 2 CH 2 CH CH Cl 3 H2 2 CH CH C 2 3 CH Ti Ti CH 3 H Ti 3 Ti CH2CH3 CH2 CH2 C Cl CH2 H2C CH Cl H2 Cl Cl H2C HC CH3 CH3 7 5.4 Ziegler-Natta Catalysis 5.5 Metal Complex Catalysis Chain Termination with Hydrogen For polypropylene, the metal center can direct the H C H C 2 Polymer chain growth – MACROGALLERIA H2 2 Polymer C C C H C Cl 2 C H2 C H2 Cl If one orientation is preferred …. then one polymer H2 H2 Ti H Ti stttructure is pre ferre d(d (ittiisotactic) H Cl H H Cl HCH3 HCH3 H CH3 H CH3 H CH3 isotactic: C C C C C H CH2 CH2 CH2 CH2 CH2 CH2 Cl CH2CH2 H Ti CH H2C Polymer CH3 HCH3 H H CH3 3 HCHH 3 H2C Cl C atactic: C C C C C C H2 H2 CH2 CH2 CH2 CH2 CH2 CH2 H2C H2 CH H CH CH3 H H CH CH3 H Cl C Cl CH2 3 H 3 3 CH2 syndiotactic: C C C C C Ti Ti CH CH CH CH H H CH2 CH2 2 2 2 2 Cl Cl 5.6 Polyethylene (PE) Types 5.7 Ziegler-Natta Catalysis Density (g/cc) Used to make a variety of polymers HDPE 0.94 - 0.97 HDPE = high density polyethylene High Density PE Formed by… Properties LLDPE 0.915 - 0.94 Linear Low Density PE H CH 2 CH2CH3 H2C LDPE 0.90 - 0.93 CH2 CH2 n Low Density PE 8 5.8 Ziegler-Natta Catalysis 5.9 Ziegler-Natta Catalysis LLDPE = linear low density polyethylene LLDPE = linear low density polyethylene mechanism H2C How are branches introduced? CHR Cl Cl Cl CH2CH3 CH2CH3 How is the branch length changed? CH2CH3 Ti Ti Ti CH2 CH C 2 Cl Cl C Cl H2 H2 How are the number and location of branches CH2 controlled? H2C H2 H2C CH2CH3 C H C H Cl C 2 CH H Cl CH2 CH2 CH2CH3 2 CHR CH2CH3 H2C Ti R Ti CH2 CH CH2 CH C 2 n Cl Cl H2 R CH2 H2C 5.10 ROMP Catalysis 6.1 Step Growth Polymerization Often referred to as condensation polymerization Metathesis L L L L M CHR L M CHR CHR No free radical or ions are necessary L M + Reactive functional groups H C CHR H2C CHR CHR 2 CH2 Ring Opening Metathesis Polymerization Polymer grows in multiple directions L L L 1:1 stoichiometry of functional groups L M CH2 L M CH2 L M A—A + B—B A—A-B—B-A—A-B—B New bonds formed during L L L step growth polymerization L M L M L M 9 6.2 Step Growth Polymerization 6.3 Step Growth Polymerization Often referred to as condensation polymerization Polymerization mixture contains wide distribution of Atom efficient? slowly growing oligomers O O H H -H O n HO C (CH ) C OH +Nn (CH ) N 2 2 4 2 6 Polyamide H H adipic acid hexamethylenediamine (HMDA) diacid + diamine O O O C (CH ) C NH (CH ) NH 2 4 2 6 n C nylon 6,6 Reactions between functional groups N H O O Amide (acid and amine) O -H2O n HO C C OH + n HO CH2 CH2 OH Ester (acid and alcohol) C Polyester O Carbonate (alcohol and acid dichloride) terephthalic acid ethylene glycol diacid + dialcohol Urethane (alcohol and isocyanate) O O O C C OCH2 CH2 O O C n O N C H O O poly(ethylene terephthalate) 6.4 Polyamides 6.5 Nylon Nomenclature First synthetic polyamide was Double-numbered: 6,6 or 6,10 poly(hexamethyleneadipamide), now called nylon 6,6 First number = Reactants? Second number = Mechanism? Single-numbered: 4 or 6 or 12 O O H H -H O Number = n HO C (CH ) C OH +Nn (CH ) N 2 2 4 2 6 H H adipic acid (C6) hexamethylenediamine (C6) O O C (CH ) C NH (CH ) NH 2 4 2 6 n nylon 6,6 molecular weight = 10,000-25,000 n = 40-110 10 6.6 Two Routes to Polyesters 6.7 Esterification Mechanism Polyester mechanism O O O O O OH + -H2O H n HO C C OH + n HO CH2 CH2 OH HO C C OH HO C C + HO CH2 CH2 OH high OH terephthalic acid ethylene glycol O O O OH H O OH -H2O C C OCH2 CH2 O HO C C OCH2 CH2 OH HO C C OCH2 CH2 OH n OH OH2 O OH O O -H+ O O HO C C O CH2 CH2 OH HO C C O CH2 CH2 OH -2n CH3OH n CH3OC C OCH3 + 2n HO CH2 CH2 OH low LeChatlier’s Principle dimethyl terephthalate (DMT) O O C C OCH2 CH2 O n 6.8 Dendrimer 6.9 Polycarbonates Polycarbonates are strong, clear plastics Carbonate = diester of carbonic acid Optical market (DVD, CD’s) CH3 O -HCl n HO C OH + n Cl C Cl CH3 phosgene dialcohol + bisphenol A dichloride CH3 O (O C OC)n CH3 11 7.1 Thermoset Polymers 7.2 Thermoset Polymers Linear polymers are typically thermoplastic Thermoset polymers are cross-linked
Recommended publications
  • Cationic/Anionic/Living Polymerizationspolymerizations Objectives

    Cationic/Anionic/Living Polymerizationspolymerizations Objectives

    Chemical Engineering 160/260 Polymer Science and Engineering LectureLecture 1919 -- Cationic/Anionic/LivingCationic/Anionic/Living PolymerizationsPolymerizations Objectives • To compare and contrast cationic and anionic mechanisms for polymerization, with reference to free radical polymerization as the most common route to high polymer. • To emphasize the importance of stabilization of the charged reactive center on the growing chain. • To develop expressions for the average degree of polymerization and molecular weight distribution for anionic polymerization. • To introduce the concept of a “living” polymerization. • To emphasize the utility of anionic and living polymerizations in the synthesis of block copolymers. Effect of Substituents on Chain Mechanism Monomer Radical Anionic Cationic Hetero. Ethylene + - + + Propylene - - - + 1-Butene - - - + Isobutene - - + - 1,3-Butadiene + + - + Isoprene + + - + Styrene + + + + Vinyl chloride + - - + Acrylonitrile + + - + Methacrylate + + - + esters • Almost all substituents allow resonance delocalization. • Electron-withdrawing substituents lead to anionic mechanism. • Electron-donating substituents lead to cationic mechanism. Overview of Ionic Polymerization: Selectivity • Ionic polymerizations are more selective than radical processes due to strict requirements for stabilization of ionic propagating species. Cationic: limited to monomers with electron- donating groups R1 | RO- _ CH =CH- CH =C 2 2 | R2 Anionic: limited to monomers with electron- withdrawing groups O O || || _ -C≡N -C-OR -C- Overview of Ionic Chain Polymerization: Counterions • A counterion is present in both anionic and cationic polymerizations, yielding ion pairs, not free ions. Cationic:~~~C+(X-) Anionic: ~~~C-(M+) • There will be similar effects of counterion and solvent on the rate, stereochemistry, and copolymerization for both cationic and anionic polymerization. • Formation of relatively stable ions is necessary in order to have reasonable lifetimes for propagation.
  • Free-Radical Photopolymerization of Acrylonitrile Grafted Onto Epoxidized Natural Rubber

    Free-Radical Photopolymerization of Acrylonitrile Grafted Onto Epoxidized Natural Rubber

    polymers Article Free-Radical Photopolymerization of Acrylonitrile Grafted onto Epoxidized Natural Rubber Rawdah Whba 1,2, Mohd Sukor Su’ait 3, Lee Tian Khoon 1,* , Salmiah Ibrahim 4, Nor Sabirin Mohamed 4 and Azizan Ahmad 1,5,* 1 Department of Chemical Sciences, Faculty of Sciences and Technology, Universiti Kebangsaan Malaysia, Bangi 43600, Malaysia; [email protected] 2 Department of Chemistry, Faculty of Applied Sciences, Taiz University, Taiz 6803, Yemen 3 Solar Energy Research Institute (SERI), Universiti Kebangsaan Malaysia, Bangi 43600, Malaysia; [email protected] 4 Centre for Foundation Studies in Science, University of Malaya, Kuala Lumpur 50603, Malaysia; [email protected] (S.I.); [email protected] (N.S.M.) 5 Research Center for Quantum Engineering Design, Faculty of Science and Technology, Universitas Airlangga, Surabaya 60286, Indonesia * Correspondence: [email protected] (L.T.K.); [email protected] (A.A.); Tel.: +60-12-7279286 (L.T.K.); +60-19-3666576 (A.A.) Abstract: The exploitation of epoxidized natural rubber (ENR) in electrochemical applications is approaching its limits because of its poor thermo-mechanical properties. These properties could be improved by chemical and/or physical modification, including grafting and/or crosslinking techniques. In this work, acrylonitrile (ACN) has been successfully grafted onto ENR- 25 by a radical photopolymerization technique. The effect of (ACN to ENR) mole ratios on chemical structure Citation: Whba, R.; Su’ait, M.S.; Tian and interaction, thermo-mechanical behaviour and that related to the viscoelastic properties of the Khoon, L.; Ibrahim, S.; Mohamed, polymer was investigated. The existence of the –C≡N functional group at the end-product of ACN-g- N.S.; Ahmad, A.
  • Dispersity Control in Atom Transfer Radical Polymerizations Through Addition of Phenyl Hydrazine

    Dispersity Control in Atom Transfer Radical Polymerizations Through Addition of Phenyl Hydrazine

    Polymer Chemistry Dispersity Control in Atom Transfer Radical Polymerizations through Addition of Phenyl Hydrazine Journal: Polymer Chemistry Manuscript ID PY-ART-01-2018-000033.R1 Article Type: Paper Date Submitted by the Author: 04-May-2018 Complete List of Authors: Yadav, Vivek; University of Houston Hashmi, Nairah; University of Houston Ding, Wenyue; University of Houston Li, Tzu-Han; University of Houston Mahanthappa, Mahesh; University of Minnesota, Department of Chemical Engineering & Materials Science; University of Wisconsin–Madison, Department of Chemistry Conrad, Jacinta; University of Houston, Robertson, Megan; University of Houston, Chemical and Biomolecular Engineering Page 1 of 32 Polymer Chemistry Dispersity Control in Atom Transfer Radical Polymerizations through Addition of Phenyl Hydrazine Vivek Yadav,a Nairah Hashmi,a Wenyue Ding,a Tzu-Han Li,c Mahesh K. Mahanthappa,d Jacinta C. Conrad,*a and Megan L. Robertson*a,b a Department of Chemical and Biomolecular Engineering University of Houston, Houston, TX 77204-4004 b Department of Chemistry University of Houston, Houston, TX 77204-4004 c Materials Engineering Program University of Houston, Houston, TX 77204-4004d Department of Chemical Engineering and Materials Science University of Minnesota, Minneapolis, MN 55455 *Email: [email protected], [email protected] †Electronic Supplementary Information available online. 1 Polymer Chemistry Page 2 of 32 Abstract Molar mass dispersity in polymers affects a wide range of important material properties, yet there are few synthetic methods that systematically generate unimodal distributions with specifically tailored dispersities. Here, we describe a general method for tuning the dispersity of polymers synthesized via atom transfer radical polymerization (ATRP). Addition of varying amounts of phenyl hydrazine (PH) to the ATRP of tert-butyl acrylate led to significant deviations in the reaction kinetics, yielding poly(tert-butyl acrylate) with dispersities Đ = 1.08 – 1.80.
  • Living Free Radical Polymerization with Reversible Addition – Fragmentation

    Living Free Radical Polymerization with Reversible Addition – Fragmentation

    Polymer International Polym Int 49:993±1001 (2000) Living free radical polymerization with reversible addition – fragmentation chain transfer (the life of RAFT) Graeme Moad,* John Chiefari, (Bill) YK Chong, Julia Krstina, Roshan TA Mayadunne, Almar Postma, Ezio Rizzardo and San H Thang CSIRO Molecular Science, Bag 10, Clayton South 3169, Victoria, Australia Abstract: Free radical polymerization with reversible addition±fragmentation chain transfer (RAFT polymerization) is discussed with a view to answering the following questions: (a) How living is RAFT polymerization? (b) What controls the activity of thiocarbonylthio compounds in RAFT polymeriza- tion? (c) How do rates of polymerization differ from those of conventional radical polymerization? (d) Can RAFT agents be used in emulsion polymerization? Retardation, observed when high concentra- tions of certain RAFT agents are used and in the early stages of emulsion polymerization, and how to overcome it by appropriate choice of reaction conditions, are considered in detail. Examples of the use of thiocarbonylthio RAFT agents in emulsion and miniemulsion polymerization are provided. # 2000 Society of Chemical Industry Keywords: living polymerization; controlled polymerization; radical polymerization; dithioester; trithiocarbonate; transfer agent; RAFT; star; block; emulsion INTRODUCTION carbonylthio compounds 2 by addressing the following In recent years, considerable effort1,2 has been issues: expended to develop free radical processes that display (a) How living is RAFT polymerization?
  • Oct 15, Controlled Polymerizations by Ki-Young Yoon

    Oct 15, Controlled Polymerizations by Ki-Young Yoon

    Wednesday Meeting Controlled Polymerizations 10/15/2014 Ki-Young Yoon Organometallics : A Friend of Total Synthesis Total Synthesis Organometallics e.g. Barry Trost Organometallics : A Friend of Polymer Synthesis Organometallics Polymer Synthesis e.g. Bob Grubbs Organometallics : Still Blue Ocean Area Total Synthesis Organometallics Polymer Synthesis In theory, every organometallic reaction can branch out into polymerization Organometallics : Still Blue Ocean Area Hydrolytic kinetic resolution E. Jacobson Science 1997, 277, 936 J. Coates J. Am. Chem. Soc 2008, 130, 17658 Enantioselective Polymerization of Epoxides: the first person who borrows Jacobson’s catalyst for the polymerization Enantioselective Polymerization of Epoxides: Catalyst which Jacobson should have used for the polymerization 10 years ago Contents 1. Polymerization Mechanism o Step-growth polymerization o Chain-growth polymerization o Step-growth vs. Chain-growth 2. Efforts to turn Step-growth polymerization into Chain-growth polymerization o GRIM polymerization o Pd-catalyzed chain-growth polymerization Polymer is a mixture Polymer is not a pure substance. It is a mixture Organic reaction Single pure product Polymerization mixture Molecular Weight Distribution Irresponsible polymer chemist Average Molecular Weight mixture - Mn, Mw, PDI (=Mw/Mn) Polymer molecular weight Number Average Molecular Weight, Mn Danny’s Credit Grade Credit*Gr ade PhysOrg 3 4.0 (A) 12 Calculus 2 3.0 (B) 6 Weight Average Molecular Weight, Mw History 1 2.0 (C) 2 Mn (4.0+3.0+2.0) =3 SEC/3 trace
  • Polymer Chemistry

    Polymer Chemistry

    Polymer Chemistry Properties and Application Bearbeitet von Andrew J Peacock, Allison Calhoun 1. Auflage 2006. Buch. XIX, 399 S. Hardcover ISBN 978 3 446 22283 0 Format (B x L): 17,5 x 24,5 cm Gewicht: 1088 g Weitere Fachgebiete > Chemie, Biowissenschaften, Agrarwissenschaften > Biochemie > Polymerchemie Zu Inhaltsverzeichnis schnell und portofrei erhältlich bei Die Online-Fachbuchhandlung beck-shop.de ist spezialisiert auf Fachbücher, insbesondere Recht, Steuern und Wirtschaft. Im Sortiment finden Sie alle Medien (Bücher, Zeitschriften, CDs, eBooks, etc.) aller Verlage. Ergänzt wird das Programm durch Services wie Neuerscheinungsdienst oder Zusammenstellungen von Büchern zu Sonderpreisen. Der Shop führt mehr als 8 Millionen Produkte. Produktinformation Seite 1 von 1 Polymer Chemistry Allison Calhoun, Andrew James Peacock Properties and Application ISBN 3-446-22283-9 Leseprobe Weitere Informationen oder Bestellungen unter http://www.hanser.de/3-446-22283-9 sowie im Buchhandel http://www.hanser.de/deckblatt/deckblatt1.asp?isbn=3-446-22283-9&style=Leseprobe 05.05.2006 2 Polymer Chemistry 2.1 Introduction In this chapter, we will see how polymers are manufactured from monomers. We will explore the chemical mechanisms that create polymers as well as how polymerization methods affect the final molecular structure of the polymer. We will look at the effect of the chemical structure of monomers, catalysts, radicals, and solvents on polymeric materials. Finally, we will apply our molecular understanding to the real world problem of producing polymers on a commercial scale. 2.2 Thermoplastics and Thermosets Thermoplastics consist of linear or lightly branched chains that can slide past one another under the influence of temperature and pressure.
  • Effect of Chain Transfer to Polymer in Conventional and Living Emulsion Polymerization Process

    Effect of Chain Transfer to Polymer in Conventional and Living Emulsion Polymerization Process

    processes Article Effect of Chain Transfer to Polymer in Conventional and Living Emulsion Polymerization Process Hidetaka Tobita ID Department of Materials Science and Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Japan; [email protected]; Tel.: +81-776-27-8767 Received: 28 December 2017; Accepted: 5 February 2018; Published: 7 February 2018 Abstract: Emulsion polymerization process provides a unique polymerization locus that has a confined tiny space with a higher polymer concentration, compared with the corresponding bulk polymerization, especially for the ab initio emulsion polymerization. Assuming the ideal polymerization kinetics and a constant polymer/monomer ratio, the effect of such a unique reaction environment is explored for both conventional and living free-radical polymerization (FRP), which involves chain transfer to the polymer, forming polymers with long-chain branches. Monte Carlo simulation is applied to investigate detailed branched polymer architecture, including 2 the mean-square radius of gyration of each polymer molecule, <s >0. The conventional FRP shows a very broad molecular weight distribution (MWD), with the high molecular weight region conforming to the power law distribution. The MWD is much broader than the random branched 2 polymers, having the same primary chain length distribution. The expected <s >0 for a given MW is much smaller than the random branched polymers. On the other hand, the living FRP shows a much narrower MWD compared with the corresponding random branched polymers. Interestingly, 2 the expected <s >0 for a given MW is essentially the same as that for the random branched polymers. Emulsion polymerization process affects branched polymer architecture quite differently for the conventional and living FRP.
  • (12) United States Patent (10) Patent No.: US 6,897.278 B2 Wilczek (45) Date of Patent: May 24, 2005

    (12) United States Patent (10) Patent No.: US 6,897.278 B2 Wilczek (45) Date of Patent: May 24, 2005

    USOO6897278B2 (12) United States Patent (10) Patent No.: US 6,897.278 B2 Wilczek (45) Date of Patent: May 24, 2005 (54) BRANCHED POLYOLEFIN SYNTHESIS K. Ishizu et al., Synthesis of AB Type Diblock Macromono mers, J. Poly. Sci. Polym. Chem., 29,923–927, 1991. (75) Inventor: Lech Wilczek, Wilmington, DE (US) J. J. Ma et al., Poly(ethylene-co-propylene)-g-polystyrene (73) Assignee: E. I. du Pont de Nemours and through Macomer Polymerization: Preparation, Morphol Company, Wilmington, DE (US) ogy, and Structure-Properties Relationships, J. Poly. Sci. Polym. Chem., 24, 2853–2866, 1986. (*) Notice: Subject to any disclaimer, the term of this P. Chaumont et al., Synthese Anionique de Polymeres Com patent is extended or adjusted under 35 portant Une Fonction Vinylsilane a Lune ou aux deux U.S.C. 154(b) by 184 days. extremites de la Chaine Macromoleculaire, Eur: Polym. J., 15, 537-540, 1979. (21) Appl. No.: 10/772,194 Y. Gnanou et al., The Ability of Macromonomers to Copo (22) Filed: Feb. 4, 2004 lymerize: A Critical Review with New Developments, Mak (65) Prior Publication Data romol. Chem., 190, 577–588, 1989. M. Arnold et al., On the Reactivity of Syryl-Terminated US 2004/0167305 A1 Aug. 26, 2004 Polystyrene Macromonomers in Anionic Copolymerization Related U.S. Application Data with Butadiene, Makromol. Chem., 192, 285–292, 1991. Slagowski et al., Upper Molecular Weight Limit for the (60) Division of application No. 10/316,454, filed on Dec. 11, 2002, now Pat. No. 6,740,723, which is a continuation-in Characterization of Polystyrene in Gel Permeation Chroma part of application No.
  • Molecular Weight Control in Emulsion Polymerization by Catalytic Chain Transfer : Aspects of Process Development

    Molecular Weight Control in Emulsion Polymerization by Catalytic Chain Transfer : Aspects of Process Development

    Molecular weight control in emulsion polymerization by catalytic chain transfer : aspects of process development Citation for published version (APA): Smeets, N. M. B. (2009). Molecular weight control in emulsion polymerization by catalytic chain transfer : aspects of process development. Technische Universiteit Eindhoven. https://doi.org/10.6100/IR642709 DOI: 10.6100/IR642709 Document status and date: Published: 01/01/2009 Document Version: Publisher’s PDF, also known as Version of Record (includes final page, issue and volume numbers) Please check the document version of this publication: • A submitted manuscript is the version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal.
  • Kinetic Study of Coordinative Chain Transfer Polymerization of Ethylene by Neodymium Metallocene Catalysts

    Kinetic Study of Coordinative Chain Transfer Polymerization of Ethylene by Neodymium Metallocene Catalysts

    Kinetic study of coordinative chain transfer polymerization of ethylene by neodymium metallocene catalysts Rodolfo André da Costa Fialho Ribeiro Thesis to obtain the Master of Science Degree in Chemical Engineering Supervisors Prof.ª Dr.ª Maria do Rosário Gomes Ribeiro Dr. Christophe Boisson Examination Committee Chairperson: Prof. Dr. Carlos Manuel Faria de Barros Henriques Supervisor: Prof.ª Dr.ª Maria do Rosário Gomes Ribeiro Member of the Committee: Prof. Dr. João Carlos Moura Bordado November 2015 This page was intentionally left blank. ii Abstract Ethylene polymerizations at 70-90ºC in toluene were performed using a combination of ∗ Cp2NdCl2Li(OEt2)2 (Cp* = C5Me5) or {Me2SiFlu2Nd(µ-BH4)[(µ-BH4)Li(THF)]}2 (Flu = C13H8) neodymium complexes with n-butyl-n-octyl-magnesium used as both alkylating and chain transfer agent. Kinetic studies were performed for the two catalytic systems by varying the Mg/Nd ratio, which is a critical parameter for polymerization control. Both systems were able to perform a controlled polymerization of ethylene and displayed the same phases on the kinetic profiles, reflecting the Coordinative Chain Transfer Polymerization mechanism. The effect of the polymerization temperature was studied for the determination of the propagation activation energy using the Arrhenius equation. A -1 ∗ value of 17.3 kcal.mol was obtained for the Cp2NdCl2Li(OEt2)2/n-butyl-n-octyl-magnesium system. The {Me2SiFlu2Nd(µ-BH4)[(µ-BH4)Li(THF)]}2/n-butyl-n-octyl-magnesium system did not display a linear Arrhenius plot and consequently the activation energy was not determined for this catalyst. Specific molar masses were targeted in order to evaluate the polymerization control efficiency.
  • Reassessment of Free-Radical Polymerization Mechanism of Allyl Acetate Based on End-Group Determination of Resulting Oligomers by MALDI-TOF-MS Spectrometry

    Reassessment of Free-Radical Polymerization Mechanism of Allyl Acetate Based on End-Group Determination of Resulting Oligomers by MALDI-TOF-MS Spectrometry

    #2009 The Society of Polymer Science, Japan Reassessment of Free-Radical Polymerization Mechanism of Allyl Acetate Based on End-Group Determination of Resulting Oligomers by MALDI-TOF-MS Spectrometry By Akira MATSUMOTO,Ã Takeo KUMAGAI, Hiroyuki AOTA, Hideya KAWASAKI, and Ryuichi ARAKAWA Allyl monomers polymerize only with difficulty and yield polymers of medium-molecular-weight or oligomers. This is attributable to ‘‘degradative monomer chain transfer.’’ However, the well-known allyl polymerization mechanism is based on only the kinetic data but any structural identification is not given. Allyl acetate (AAc), a most typical allyl monomer, was polymerized radically and the resultant oligomeric poly(AAc)s were characterized using MALDI-TOF-MS spectrometry in order to reassess the AAc polymerization mechanism proposed by Litt and Eirich. The induced decomposition of benzoyl peroxide by both growing polymer radical and monomeric allyl radical was presumed but it was never of importance. Then, the fate of resonance-stabilized monomeric allyl radical generated via monomer chain transfer of growing polymer radical was pursued in terms of the competition between the initiation of a new polymer chain and the chain stopping reaction of a growing polymer radical providing monomeric allyl groups as the initial and terminal end-groups, respectively. The À2 monomer chain transfer constant was estimated to be 3:73 Â 10 from the Pn value of poly(AAc) obtained at a low initiator concentration where the coupling termination of growing polymer radical with
  • Polymer Chemistry (C212)

    Polymer Chemistry (C212)

    Polymer Chemistry (C212) Prof. Dr. Afaf M. Abdelhameed [email protected] [email protected] Anionic Addition Polymerization The mechanism of anionic polymerization is a kind of repetitive conjugate addition reaction (the "Michael reaction" in organic chemistry).This polymerization is carried out through a carbanion active species. Like all addition polymerizations, it takes place in three steps: chain initiation, chain propagation, and chain termination. Anionic polymerizations are used in the production of polydiene synthetic rubbers, solution styrene/butadiene rubbers (SBR), and styrenic thermoplastic elastomers. Monomer Characteristics In order for polymerization to occur with vinyl monomers, the substituents on the double bond must be able to stabilize a negative charge. Stabilization occurs through delocalization of the negative charge. Because of the nature of the carbanion propagating center, substituents that react with bases or nucleophiles either must not be present or be protected. Examples of vinyl monomers. Vinyl monomers with substituents that stabilize the negative charge through charge delocalization, undergo polymerization without termination or chain transfer.[2] These monomers include styrene, dienes, methacrylate, vinyl pyridine,aldehydes, epoxide, episulfide, cyclic siloxane, and lactones. Polar monomers, using controlled conditions and low temperatures, can undergo anionic polymerization. However, at higher temperatures they do not produce living stable, carbanionic chain ends because their polar substituents can undergo side reactions with both initiators and propagating chain centers. The effects of counterion, solvent, temperature, Lewis base additives, and inorganic solvents have been investigated to increase the potential of anionic polymerizations of polar monomers.[2] Polar monomers include acrylonitrile, cyanoacrylate, propylene oxide, vinyl ketone, acrolein, vinyl sulfone, vinyl sulfoxide, vinyl silane and isocyanate.