AN ABSTRACT OF THE THESIS OF Turgav Seckin for the degree of Master of Science in Chemistry presented on August 26, 1987 TITLE : Polybenzimidazole Synthesis Frog Comnounds with Sulfonate Ester Linkages Redacted for privacy Abstract approved : Dr. R.W. THIES This investigation of polybenzimidazole synthesis involvedthe two-stage low temperature solution polymerization of dialdehydes, One-step polycondensation of dialdehydes,two-stage melt polyconden- sation of diesters, and one-step solutionpolycondensation of diesters with 3,3'-diaminobenzidine. Dialdehyde or diester monomers were prepared which contained aromatic units whichwere hooked toget- her with sulfonate linkages. Polymerization of these monomers with 3,3'-diaminobenzidine resulted in moderate viscosities of0.4-0.8 dlg in DMSO at 19°C. The polybenzimidazoles obtained appear to be linear; most of them when tested immediatelyafter preparation, were largely soluble in certain acidicor dipolar approtic solvents. Films, obtained by dissolving the polymerin dipolar approtic solvents such as N,N-dimethylacetamideor N,N-dimethyl formamide, were flexible, clear, yellow to brown in color, and foldable depen- ding upon which monomers and which polymerization methodswere used. Polybenzimidazole Synthesis From Compounds with Sulfonate Ester Linkages by Turgay Seckin A THESIS submitted to Oregon State University in partial fulfillment of the requirements for the degree of Master of Science Completed August 26, 1987 Commencement June 1988 APPROVED Redacted for privacy Professor of Chemistry in Charge ofMajor Redacted for privacy Chairman of Department of Chemistry Redacted for privacy Dean of G ad ate School Date thesis is prepared August 17, 1987 Thesis typed by Turgay Seckin To my family for their never failing love andsupport NE MUTLU TURKUM DIYENE ACKNOWLEDGEMENT I would like to thank Prof. R.W. Thiesfor his helpful guidance and enthusiasm. I would also like to thank Prof. G.J. Gleicher, Prof. P.K. Freeman and Prof. J.H.Krueger for their helpful comments. And a special thanks to allmy friends with whom I shared unforgettable moments in andout of lab. Most importantly, I wish to thank my family for their love,devotion, and moral support. The financial support provided bythe Ministry of Youth of Education of Republic of Turkeyis also acknowledged. TABLE OF CONTENTS I. INTRODUCTION 1 1.1. GENERAL BACKGROUND 1 1.2. CLASSIFICATION OF POLYMERS 8 1.3. KINETICS OF STEP POLYMERIZATION 11 1.4. VISCOSITY MEASUREMENTS OF POLYMERS 12 1.5. THE VISCOSITY AVERAGE MOLECULAR WEIGHT 12 1.6. THERMALLY STABLE POLYMERS 14 1.7. POLYBENZIMIDAZOLES 15 1.8. APPLICATION OF POLYBENZIMIDAZOLES 37 II. OBJECTIVES OF THIS STUDY 44 III. RESULTS AND DISCUSSION 45 II1.1. MONOMER SYNTHESES 45 111.2. POLYMERIZATION REACTIONS 51 IV. EXPERIMENTAL 67 IV.1.a. SYNTHESES OF MONOMERS 67 IV.1.b. SYNTHESES OF DISULFONYLCHLORIDES 69 IV.2. POLYMERIZATION 73 IV.3. POLYMER FILMS 82 1V.4. VISCOSITY MEASUREMENT 82 V. MOLECULAR WEIGHT CALCULATION 84 VI. CONCLUSION 87 BIBLIOGRAPHY 88 APPENDIX 91 LIST OF FIGURES FIGURE PAGE 1 Distribution of molecular weight ina typical polymer 3 2 Tg transitions and Tmtemperatures 6 3 Mechanical strength ofa polymer 6 4 Molecular weight of a polymer 13 5 Mark-Howink-Sakadura relation 13 6 Determination of (a) value 13 7 The relationship of propertiesto temperatures through th Tg region 15 8 The approximate ninh of PBIas function of Molecular weight 37 9 Limiting oxygen index ofa PBI 40 10 Dependence of DP onr and p 85 LIST OF TABLES TABLE PAGE 1 Fuoss constants of polybenzimidazoles 36 2 Inherent viscosity versus application 38 3 Monomers used for preparation of polymers 49 4 Two-stage melt polymerization of diesters 52 5 Two-stage melt polycondensation 53 6 Two-stage low temperature solution polycondensation 55 7 PBI synthesis with two dialdehydes 55 8 PBI synthesis with different ratios ofmonomers 56 9 PBI synthesis with different ratios ofmonomers 57 10 One-step dialdehyde polycondensation 58 11 PBI synthesis with BDS-1,3 59 12 PBI synthesis with BDS-1,3 59 13 PBI synthesis with NDS-2,6 60 14 PBI synthesis with NDS-2,6, andNDS-1,5 61 15 PBI synthesis with NDS-1,5 62 - 16 One-step PBI synthesis insulfolane 64 17 One-step solution polycondensationof diesters 65 18 PBI synthesis with bisorthoesters 66 19 Molecular weight calculations 84 20 MW calculation 86 POLYBENZIMIDAZOLE SYNTHESIS FROM COMPOUNDS WITHSULFONATE ESTER LINKAGES I. INTRODUCTION I.I. GENERAL BACKGROUND I.l.a. Polymers in General Polymer, a high molecular weightsubstance, is built by linking large numbers of smaller molecules knownas monomers. Polymerization could be definedas a reaction in which monomer molecules react each otherto form giant molecules. nCH2 CH2 (CH2 CH2)n- Polyethylene n 100,..10000,..etc. I.1.b. PROPERTIES OF POLYMER 1 Properties of polymer vary dependingon which polymerization met- hods, conditions, andmonomers are used. The combinations of pro- perties possessed bya particular polymer determines the application of the polymeras fiber or a plastic. With this idea in mind polymer properties could be classifiedin four different groups.2 A. Chemical structure B. Molecular weight C. Molecular shape D. Physical state A. CHEMICAL STRUCTURE a. Non-polar polymer -(CH2-CH2)n-Polyethylene -(CH2-CH)n- 1 CH3 Polypropylene 2 b. Polar polymer -(C0(02)4CONH(CH2)6NH)n- Polyamides c. Streamlined polymer chain (Non-bulky) -(CH2-CH2)n- Polyethylene d. Bulky chain (Bulky side groups) Polystyrene B. MOLECULAR WEIGHT QE A =Me A knowledge of the molecular weightof a polymer is necessary to understand the relationship betweenstructure, properties, and its synthesis and applications. The molecular weight of a polymer is quite different from the molecularweight of small-sized compounds. Since polymers invariably containdifferent species of different chain lengths, molecular weightstudies always yield average 3 values . Polymers are polydisperse andheterogeneous in molecular weight, because polymerizationis a random process. The statistical variations present in thepolymerization process give rise to the polydispersity of polymers.When one discusses the molecular weight of a polymer one is actuallyinvolved with its average molecular weight. Both the average molecular weightand the exact distribution of different molecular weights in a polymer are required in orderto fully characterize it. The control of molecular weight (MW), and molecular weight distribution(MWD) is often used to obtain and improve certain desired physicalproperties in a polymer sample. There are numerous methodsto determine the molecular weight ofa polymer4. 3 a./. EXPERIMENTAL =moor gEMOLECULAR WEIGHT Q A POLYMER A. number averazq molecular weight (Mn), isdetermined by the measurement of colligative properties suchas freezing point depression (crosscut), boiling pointelevation (ebulliometry), osmotic pressure, and vaporpressure lowering. Mn is defined as the total weightw of all the molecules in a polymer sample divided by the total numbers ofmoles present Mn w/Mific ElfxMx/INx zad to "-Gm Ne the numbers of moles whose weight- Mx B. Dm weight - average molecular weight(1w), is obtained from the light scattering measurements andis defined as, Mw Etrift x- weight fraction of molecules whose molecular weight Is Mx. C. Ihs vtgposity average molecularweight (Mv) is obtained from viscosity measurements and isdefined by Mv (EwxM0)1/a (721ztixa+1xtlx)1/a where a is a constant FIGURE -L- Distribution of M.W.in a typical polymer sample4 lk 4eatier .Mgt, 4 C. MOLECULAR SHAPE QE POLYMERS Linear Branched-long branches Branched-short branches Branched-branches protruding from branches give a dendritic structures. Cross-linked D. PHYSICAL STATE QE POLYMERS 1. Thermal transitions: Polymeric materials are characterized by two major types of transition temperatures. 5 Tm : Crystalline meltingtemperature Tg : Glass transitiontemperature "Crystalline meltingtemveraturt is the melting temperature of the crystalline domains ofa polymer sample"1. "The glass transitionstemperature is the temperature at which the amorphous domains ofa polymer take on the characteristicproperties of the glassy state-brittleness,stiffness, and rigidityl. The difference betweentwo thermal transitions can be understood more clearly by considering changes which take place in a polymeras it is cooled. "The translational,rotational, and vibrational energies of the polymer moleculesgo down on cooling. When the total energies of the polymer moleculeshave fallen to the point where the translational and rotationalenergies are zero, crystallization is possible. If certain symmetryrequirements are met, the molecules are able to pack into an orderedlattice arrangement and crystallization takes place. The temperature at which this takes place is Tm. However not all polymerspossess the essential symmetry requirements for crystallization. If crystallization requirements aren't met crystallizationis not possible, but the energies of molecules continueto decrease as the temperature decreases. A temperature is finally reachedthe Tg, at which the motions of the polymer chainsstop due to the lack of bond rotation"1. Determination of glass transitionand crystalline melting temperatures by changes in specificvolume is plotted in Figure -2- A polymer may possess just a Tg if it is amorphous onlyor just a Tm if it is crystallineonly. 6 FIGURE-2-Glass transition and crystallinemelting temperature reporeftre Crystalline polymerspossess high molecular forces, compact molecular structure, and highly regular structure. Polymers with