Principles of Polymer Chemistry

A. Ravve Consultant in Polymer Chemistry Lincolnwood, Illinois

PLENUM PRESS • NEW YORK AND LONDON

Contents

1. Introduction 1.1. Definitions 1 1.2. Nomenclature of Polymers 5

1.2.1. NomenclatureofChain-Growth Polymers 5 1.2.2. Nomenclature of Step-Growth Polymers 6

1.3. Structure and Property Relationship in Organic Polymers 7 1.3.1. Effects of Dipole Interactions 7 1.3.2. Induction Forces in Polymers 7

1.4. Amorphous and Crystalline Arrangements in Thermoplastic Polymers .9 1.4.1. The Amorphous State 9 1.4.2. Elasticity 9 1.4.3. Crystallinity 10 1.4.4. Liquid Crystal Polymers 12 1.4.5. Orientation 13 1.4.6. First-Order Transition Temperature 13 1.4.7. Second-Order Transition Temperature 13

1.5. Effect of Chemical Structure upon Physical Properties 14 1.6. Molecular Weights and Molecular Weight Determinations 16 1.7. Steric Arrangement in Macromolecules 24 1.8. Optical Activity in Polymers 25 Appendix 26

A.l. Additional Definitions 26 A.2. Program for Calculating Molecular Weights from Gel Permeation

Chromatograms 26 Review Questions 31 References 33

2. Free-Radical Chain-Growth Polymerization 2.1. Free-Radical Chain-Growth Polymerization Process 35 2.2. Reactions Leading to Formation of Initiating Free Radicals 37

2.2.1. Thermal DecompositionofAzo Compound, and Peroxides 37 2.2.2. Bimolecular Initiating Systems 40 2.2.3. Boron Alkyls and Metal Alkyl Initiators of Free-Radical Polymerizations . . . 43 2.2.4. Photochemical Initiators 43 2.2.5. Initiation of Polymerization with Radioactive Sources and Electron Beams . . 43

Vlii 2.3. Capture of the Free Radical by the Monomers 44 2.4. Propagation 46

CONTENTS 2.4.1. Steric, Polar, and Resonance Effects in the Propagation Reaction 46 2.4.2. Effect of Reaction Medium 48 2.4.3. Ceiling Temperature 49 2.4.4. Autoacceleration . 50 2.4.5. Polymerization of Monomers with Multiple Double Bonds 51

2.5. The Termination Reaction 52 2.6. Copolymerization 55

2.6.1. Reactivity Ratios 56 2.6.2. Q and e Scheme 57

2.7. Terpolymerization 58 2.8. Allylic Polymerization 59 2.9. Inhibition and Retardation 59 2.10. Thermal Polymerization 62 2.1 l.Donor-AcceptorComplexes in Copolymerization 63 2.12. Polymerization ofComplexes with Lewis Acids 67 2.13. Steric Control in Free-Radical Polymerization 68 2.14. Polymer Preparation Techniques 69 Review Questions 73 References 75

3. lonic Chain-Growth Polymerization 3.1.Chemistry of IonicChain-Growth Polymerization 81 3.2. Kineticsof lonic Chain-Growth Polymerization 81 3.3. Cationic Polymerization 84

3.3.1. Two-Electron Transposition Initiation Reactions 85 3.3.1.1. Initiation by Protonic Acids 85 3.3.1.2. Lewis Acids in Cationic Initiations 86 3.3.1.3. Initiation by Stable Cations 89 3.3.1.4. Metal Alkyls in Initiations of Cationic Polymerizations 90

3.3.2. One-Electron Transposition Initiation Reactions 91 3.3.2.1. Charge Transfer Complexes in lonic Initiations 92 3.3.2.2. Radiation-Initiated Polymerizations 93 3.3.2.3. Electroinitiation of Polymerization 93

3.3.3. Propagation in Cationic Polymerization 94 3.3.3.1. Steric Control in Cationic Polymerization 96 3.3.3.2. Pseudocationic Polymerization 100 3.3.3.3. Isomerization Polymerization 100

3.3.4. Termination Reactions in Cationic Polymerizations 103 3.4. Anionic Polymerization ofOlefins 105

3.4.1. Initiation in Anionic Chain-Growth Polymerization 105 3.4.1.1. Initiation by Addition of an Anion to an Olefin 105 3.4.1.2. One-Electron Transfer Initiation 108 3.4.1.3. Initiations by Alfin Catalysts 111 3.4.1.4. Electroinitiation of Anionic Polymerizations 112

3.4.2. Propagation in Anionic Chain-Growth Polymerization 112 3.4.2.1. Steric Control in Anionic Polymerization 113 3.4.2.2. Hydrogen Transfer Polymerization 117

3.4.3. Termination in Anionic Polymerization 118

3.5. Coordinated Anionic Polymerizations 120 3.5.1. Heterogeneous Ziegler-Natta Catalysts 121 3.5.2. Homogeneous Ziegler-Natta Catalysts 125 3.5.3. Steric Control in Polymerizations ofConjugatedDienes 127 3.5.4. Current Industrially Developed Ziegler-Natta Catalysts 128 3.5.5. Effect of Lewis Bases 130 3.5.6. Terminations in Coordination Polymerizations . 130 3.5.7. Reduced Transition Metal Oxide Catalysts on Support 131 3.5.8. Isomenzation Polymerizations with Coordination Catalysts . . . . . . . . . 132

3.6. Polymerization of Aldehydes 132 3.6.1. Cationic Polymerization of Aldehydes 133 3.6.2. Anionic Polymerization of Aldehydes 134 3.6.3. Polymerization of Unsaturated Aldehydes 137 3.6.4. Polymerizations ofDialdehydes 138

3.7. Polymerization of Ketones and Isocyanates 138 3.8. Copolymerizations by Ionic Mechanism 139 3.9. Group Transfer Polymerization 141 3.10. Configurational Statistics and the Propagation Mechanism in

Chain-Growth Polymerization 142 Review Questions 146 Appendix. Computer Program for Analyses of Polymers with Configurational

Statistics and NMR Spectra 148 References 158

4. Ring-Opening Polymerizations 4.1. Chemistryof Ring-Opening Polymerizations 167 4.2. Kinetics of Ring-Opening Polymerizations 167 4.3. Polymerization of Oxiranes 168

4.3.1. Cationic Polymerization . 168 4.3.2. Anionic Polymerization 171 4.3.3. Polymerization by Coordination Mechanism 172 4.3.4. Steric Control in Polymerizations of Oxiranes 175

4.4. Polymerization of Oxetanes 177 4.4.1. The Initiation Reaction 177 4.4.2. The Propagation Reaction 178

4.5. Polymerization ofTetrahydrofurans 179 4.5.1. The Initiation Reaction 179 4.5.2. The Propagation Reaction 180 4.5.3. The Termination Reaction 181

4.6. Polymerization of Oxepanes 182 4.7. Ring-Opening Polymerizations ofCyclic Acetals . 182

4.7.1. Polymerization ofTrioxane 182 4.7.2. Polymerization ofDioxolane 184 4.7.3. Polymerization ofDioxepane 185

4.8. Polymerization ofLactones 186 4.8.1. Cationic Polymerization ofLactones 186 4.8.2. Anionic Polymerization ofLactones 187 4.8.3. Polymerization of Lactones by a Coordination Mechanism 187 4.8.4. Special Catalysts for Polymerizations ofLactones 188

4.9. Polymerization ofLactams 189 4.9.1. Cationic Polymerization ofLactams 190

X 4.9.2. Anionic Polymenzation ofLactams 194 4.9.3. HydrolyticPolymerizationofLactams 200

CONTENTS 4.10. Polymenzation of N-Carboxy-a-AminoAcidAnhydrides 201 4.1 l.Metathesis Polymenzation ofAlicyclics 204 4.12. Polymenzation ofCyclic Amines 205 4.13. Ring-Opening Polymenzation ofCyclic Sulfides 207 4.14. Copolymerization ofCyclic Monomers 208 4.15. Spontaneous Alternating Zwitterion Copolymerizations 210 4.16. Ring-Opening Polymerizations bya Free-Radical Mechanism 213 Review Questions 214 References 216

5. Common Chain-Growth Polymers 5.1. Polyethylene and Related Polymers 223

5.1.1. Preparation of Polyethylene bya Free-Radical Mechanism 223 5.1.2. Commercial High-Density Polyethylene, Properties and Manufacture . . . . 225 5.1.3. Materials Similarto Polyethylene 228

5.2. Polypropylene 229 5.2.1. Manufacturing Techniques 231 5.2.2. Syndiotactic Polypropylene 231

5.3. Polyisobutylene 232 5.4. Higher Poly(a-olefin)s 233

5.4.1. Properties of Poly(a-olefin)s 233 5.4.2. Poly(butene-l) 233 5.4.3. Poly(4-methylpentene-l) 234

5.5. CopolymersofEthylene and Propylene 235 5.5.1. Ethylene-Propylene Elastomers 235 5.5.2. Copolymersof Ethylene with a-Olefins 236 5.5.3. Copolymersof Propylene withDienes 237 5.5.4. Copolymersof Ethylene with VinylAcetate 237 5.5.5. Ionomers 237

5.6. Homopolymers of Conjugated Dienes 237 5.6.1. Polybutadiene 237

5.6.1.1. Liquid Polybutadiene 238 5.6.1.2. High Molecular Weight Polybutadiene 239

5.6.2. Polyisoprene 241 5.6.2.1. Natural Polyisoprenes 241 5.6.2.2. Synthetic Polyisoprenes 241

5.7. Methyl Rubber, Poly(2,3-dimethylbutadiene) 242 5.8. Chloroprene Rubber, Poly(2-chloro-l,3-butadiene) 243 5.9. Miscellaneous Polymers from Dienes 244 5.10. Cyclopolymerization of Conjugated Dienes 245 5.11. Copolymersof Dienes 245

5.11.1. GR-S Rubber 246 5.11.2. GR-N Rubber 247

5.12. Polystyrene and Polystyrene-Like Polymers 248 5.12.1. Preparation of Polystyrene 248 5.12.2. Polystyrene Prepared bylonic Chain-Growth Polymerization 249 5.12.3. Polymers from Substituted Styrene 250

5.13. Copolymersof Styrene 252 5.13.1. High-Impact Polystyrene 252

5.13.2. ABS Resins 253 Xi 5.13.3. Copolymers of Styrene with Maleic Anhydride 253

5.14. Polymers ofAcrylic and Methacrylic Esters 254 CONTENTS 5.14.1. Polymerizations of Acrylic and Methacrylic Esters 254 5.14.2. Acrylic Elastomers 256 5.14.3. Thermoplastic and Thermoset Acrylic Resins 257

5.15. Acrylonitrile and Methacrylonitrile Polymers 258 5.16. Polyacrylamide, Poly(acrylic acid), and Poly(methacrylic acid) 260 5.17. Halogen-Bearing Polymers 261

5.17.1. Polytetrafluoroethylene 261 5.17.2. Polychlorotrifluoroethylene 261 5.17.3. Poly(vinylidine fluoride) 262 5.17.4. Poly(vinyl fluoride) 262 5.17.5. Copolymers ofFluoroolefins 262 5.17.6. Miscellaneous Fluorine Containing Chain-Growth Polymers 263 5.17.7. Poly(vinyl Chloride) 264 5.17.8. Poly(vinylidine Chloride) 267

5.18. Poly(vinyl acetate) 267 5.19. Poly(vinyl alcohol) and Poly(vinyl acetal)s 268 Review Questions 269 References 271

6. Step-Growth Polymerization and Step-Growth Polymers 6.1. Mechanism and Kinetics of Step-Growth Polymerization 279

6.1.1. ReactionsofFunctionalGroups 279 6.1.2. Kinetic Considerations , . 280 6.1.3. Ring Formation in Step-Growth Polymerization 285 6.1.4. Techniquesof Polymer Preparation 286

6.2. Polyesters 286 6.2.1. Linear Saturated Polyesters 287

6.2.1.1. Synthetic Methods 287 6.2.1.2. Commercial Linear Saturated Polyesters 290 6.2.1.3. Copolyesters 293

6.2.2. Linear Unsaturated Polyesters 294 6.2.3. Network Polyesters for Surface Coatings 297 6.2.4. Polycarbonates 298 6.2.5. Polyesters fromLactones 300

6.3. Polyamides 300 6.3.1. Nylons 301 6.3.2. Fatty Polyamides 309 6.3.3. Special Reactions for Formation of Polyamides 310 6.3.4. Aromatic Polyamides 311

6.4. Aromatic Polyamide-Imides and Aromatic Polyester-Imides 313 6.5. Polyimides 316 6.6. Polyethers 321

6.6.1. Poly(phenylene oxide)s 321 6.6.2. Phenoxy Polymers 323

6.7. Polyacetals and Polyketals 324 6.8. Poly(p-xylylene)s 325 6.9. Sulfur-Containing Polymers 327

6.9.1. Polysulfones 327 6.9.2. Polythioethers and Polymercaptals 329

XÜ 6.10. Polyurethanes 331 6.10.1. Preparations of Polyfunctional Isocyanates 331

CONTENTS 6.10.2. Commercial Polyisocyanates 331 6.10.3. Reactions of the Isocyanates 332 6.10.4. The Effect ofCatalysts 332 6.10.5. Polyurethane Fibers 333 6.10.6. Polyurethane Elastomers 334 6.10.7. Polyurethane Foams 335

ö.ll.Epoxy Resins 335 6.11.1. Preparation of Commercial EpoxyResins 335 6.11.2. The Crosslinking Reactions 336 6.11.3. Cycloaliphatic Epoxides 342

6.12. Phenol-Formaldehyde Resins 342 6.12.1. Resols 343 6.12.2. Novolacs 346 6.12.3. Ammonia-Catalyzed Phenolic Resins 348 6.12.4. Typical Commercial Preparations 348

6.13. Aminopolymers 349 6.13.1. Urea-Formaldehyde Resins 349 6.13.2. Melamine-Formaldehyde Resins 350

6.14. Silicone Polymers 350 6.14.1. Polysiloxanes . 351 6.14.2. Silicone Elastomers 352 6.14.3. Polysiloxane Coating Resins 353 6.14.4. Fluorosilicone Elastomers 354 6.14.5. Polyarylsiloxanes 354

6.15. Polysilanes 355 6.16. Phosphonitrilic Polymers 355 6.17. High-Performance Polymers 356

6.17.1. Fluorine-Containing Aromatic Polymers 357 6.17.2. Polyphenylene 358 6.17.3. Diels-Alder Polymers 359 6.17.4. Silicone-Containing Aromatic Polymers 363 6.17.5. Direct Condensation Polymers 364

6.17.5.1. Polybenzimidazoles,Polybenzthiazoles, and Related Polymers . . 364 6.17.6. Oligomers with Terminal Functional Groups 366 6.17.7. Cardo Polymers 368 6.17.8. Double Stranded Polymers ,, 368 6.17.9. Poly(aryleneether)s and Poly(arylene ether ketone)s 370

Review Questions 371 References 374

7. Naturally Occurring Polymers 7.1. Polymers ThatOccur in Nature 381 7.2. Polysaccharides 381

7.2.1. Hemicelluloses 381 7.2.2. Starch 382 7.2.3. Cellulose 383

7.2.3.1 Regenerated Cellulose 383 7.2.3.2. Derivatives of Cellulose 384

7.2.4. Miscellaneous Polysaccharides 387

7.3.Lignin 388 XÜi 7.4. Polyisoprene 388 7.5. Proteins 389 CONTENTS

7.5.1. a-Amino Acids 389 7.5.2. Structures and Chemistryof Proteins 389 7.5.3. Synthetic Methods for the Preparation of Polypeptides 394 7.5.4. Chemical Modification of Proteins 396

7.6. Nucleic Acids 396 7.6.1. DNA and RNA 398 7.6.2. Synthetic Methods for the Preparation of Nucleic Acids 398

7.7 Polyalkanoates 399 Review Questions 400 References 401

8. Reactions of Polymers 8.1.Reactivity of Macromolecules 403

8.1.1. Diffusion-Controlled Reactions 404 8.1.2. Paired Group and Neighboring Group Effects 405 8.1.3. Effect ofMolecularSize 405 8.1.4. Effects ofChanges in Solubility 406 8.1.5. Effects ofCrystallinity 406 8.1.6. Reactions That Favor Large Molecules 407

8.2. Addition Reactions of Polymers . 407 8.2.1. Halogenation 407 8.2.2. Hydrogenation 409 8.2.3. Addition ofCarbenes 409 8.2.4. Electrophilic Additionsof Aldehydes 410 8.2.5. Polar Additions 411

8.2.5.1. Michael Condensation 411 8.2.5.2. Hydroboration 411 8.2.5.3.1,3-Dipolar Additions 411 8.2.5.4. The EneReaction 412 8.2.5.5. The Ritter Reaction 413 8.2.5.6. Diels-Alder Condensations 413 8.2.5.7. Epoxidation Reactions 414

8.3. Rearrangement Reactions 415 8.3.1. Isomerization Reactions 415 8.3.2. Cyclizations and Intramolecular Rearrangements 416

8.4. Substitution Reactions 419 8.4.1. Substitution Reactions of Saturated Polymerie Hydrocarbons 419 8.4.2. Substitution Reactions of Halogen-Bearing Polymers 421 8.4.3. Substitution Reactions of Polymers with Aromatic Rings 425

8.4.3.1. Halogenation Reactions ofPolystyrene 425 8.4.3.2. Chloromethylation Reactions 425 8.4.3.3. Reactions ofHalomethylated Polymers 426 8.4.3.4. Friedel-Craft Alkylation Reactions . 428 8.4.3.5. Sulfonation Reactions 429 8.4.3.6. Nitration, Reduction, and Diazotization 429 8.4.3.7. Metalation Reactions 430

8.4.4. Reactions of Acrylic, Methacrylic, and Related Polymers 431 8.4.4.1. Reduction of the Ester Groups 431 8.4.4.2. Nucleophilic and Electrophilic Substitutions 432

XJV 8.4.5. Substitution Reactions of Poly(vinyl alcohol) 434 8.4.6. Miscellaneous Exchange Reactions 435

CONTENTS 8.5. Crosslinking Reactions of Polymers 437 8.5.1. Vulcanization of Elastomers 437 8.5.2. Crosslinking With the Aid of Peroxides 438 8.5.3. Miscellaneous Crosslinking Reactions of Polymers 439 8.5.4. Radiation Crosslinking 439 8.5.5. Photocrosslinking of Polymers 440

8.5.5.1. Photocrosslinkingof Polymers with Light-Sensitive Groups 441 8.5.5.2. Ultraviolet Light Curing Technology ofCoatings 445

8.5.6. Crosslinking of Polymers With Electron Beams 449 8.6. Polymerie Reagents 450

8.6.1. Immobilized Reagents 450 8.6.2. Polymerie Catalysts 452

8.7. Formation of Graft Copolymers 454 8.7.1. Free-Radical Graftingby the Chain-Transferring Technique 455 8.7.2. Free-Radical Grafting Reactions to Polymers with Double Bonds . 456 8.7.3. Preparation of Graft Copolymers With the Aid ofMacromonomers 457 8.7.4. Initiations of Polymerizations from the Backbone Polymers 457 8.7.5. Photochemical Synthesesof Graft Copolymers 461 8.7.6. Graft-Copolymer Formation With the Aid of High-Energy Radiation 462 8.7.7. Preparation of Graft Copolymers With Ionic Chain-Growth and

Step-Growth Polymerization Reactions 462 8.7.8. Miscellaneous Graft Copolymerizations 465

8.8. Block Copolymers 465 8.8.1. Block Copolyesters 465 8.8.2. Block Copolyamides 466 8.8.3. Polyurethane-Polyamide Block Copolymers 466 8.8.4. Polyamide-Polyester Block Copolymers 467 8.8.5. Polyurethane Ionomers 467 8.8.6. Block Copolymers ofPoly(a-olefin)s 467 8.8.7. Simultaneous Use of Free-Radical and Ionic Chain-Growth Polymerizations . . 468 8.8.8. Preparationof Block Copolymers by Homogeneous Ionic Copolymerization . . 468 8.8.9. Special Reactions for Preparation of Block Copolymers 470 8.8.10. Miscellaneous Block Copolymers 471 8.8.1 l.MechanochemicalTechniques for Formation of Block Copolymers 472

8.9. Conductive Polymers 472 Review Questions 475 References 477

Appendix 487

Index 489