Polymer Synthesis - GBV

Paul Rempp and Edward W. Merrill

Polymer Synthesis 2nd, revised Edition

Hüthig & Wepf Verlag Basel • Heidelberg • New York

Table of Contents

Part I: Polymerization Reactions Chapter 1: General Considerations about Polymers and Polymer Synthesis

1.1 Introduction 21 1.2 Polymerization Reactions 21 1.2.1 Step Growth Polymerizations 22 1.2.2 Chain Growth Polymerizations 22 1.2.3 Thermodynamics 23 1.3 Structural Characteristics of Polymers: Shape and Size 24 1.3.1 Placement of the Monomer Units and Stereoregularity 25 1.3.1.1 Tacticity of Vinyl Polymers 25 1.3.1.2 Stereoregularity of Diene Polymers 27 1.3.1.3 Stereoregularity of Polymers Resulting from Ring Opening Polymeri

zation 27 1.3.2 Homopolymers and Copolymers 28 1.4 Molecular Weight Distribution and Molecular Weight Averages . . . 29

Chapter 2: Step-Growth Polymerization (Polycondensation)

2.1 Introduction 35 2.2 Calculation of Molecular Weights and Molecular Weight Distribu

tions of Polycondensates 40 2.2.1 Molecular Weight Averages 40 2.2.2 Molecular Weight Distributions 42 2.2.2.1 Polycondensates Obtained from ab Type Base Molecules 42 2.2.2.2 aa + bb Type Polycondensates 44 2.3 Kinetics of Step-Growth Polymerization in Homogeneous Systems. 46 2.4 Network Formation by Step-Growth Polymerization 48 2.5 Examples of Step-Growth Polymerization Reactions 50 2.5.1 Polyesters 50 2.5.2 Polyamides 52 2.5.3 Polyurethanes 52 2.5.4 Polycarbonates 53 2.5.5 Polybenzimidazoles and Aromatic Polyimides 54 2.5.6 Crosslinked Polycondensates 54 2.6 Special Cases of Polycondensation Reactions 57 2.6.1 Branched Uncrosslinked Polycondensates 57 2.6.2 Chain Extension Reactions 58 2.6.3 Polyrecombination Reactions 59 2.6.4 Ionenes 60 2.6.5 Polyphenylene Oxides 60

10 Table of Contents

Chapter 3: free Radical Chain Polymerization

3.1 Introduction 65 3.2 Initiators and Monomers Fitted for Free Radical Polymerization .. 65 3.2.1 Initiators and Initiation Processes 65 3.2.2 Monomers 67 3.3 Mechanism of Free Radical Polymerization 68 3.3.1 Initiation 68 3.3.2 Propagation 69 3.3.3 Termination 70 3.3.4 Transfer Reactions 70 3.3.5 Remarks 71 3.4 Kinetics of Free Radical Polymerization 72 3.5 Kinetic Chain Length, Average Degree of Polymerization and Mole

cular Weight Distribution 76 3.6 Influence of Transfer Reactions on the Degree of Polymerization .. 78 3.7 Determination of Rate Constants in Homogeneous Free Radical

Polymerization 81 3.8 Temperature Dependence of Rate Constants and of Degrees of

Polymerization 83 3.9 Trommsdorff Effect 84 3.10 Telomerization 86 3.11 "Living" Free Radical Polymerizations 86

Chapter 4: Free Radical Copolymerization

4.1 Introduction 92 4.2 Copolymerization and Compositional Heterogeneity 93 4.2.1 Plots of the Instantaneous Copolymer Composition 95 4.2.2 Variation of Copolymer Composition versus Conversion 98 4.3 Determination of the Radical Reactivity Ratios 100 4.3.1 Methods 100 4.3.2 Experimental Procedures 103 4.4 Factors Affecting the Copolymerization Reactivity 104 4.5 Q-e-Scheme 105 4.6 Kinetics of Radical Copolymerization 106 4.7 Sequence Distributions in Radical Copolymerization 108 4.8 Penultimate Effects 110 4.9 Crosslinking Free Radical Copolymerization I l l 4.10 Some Specific Cases 112 4.10.1 Polyalkylene Sulfones 112 4.10.2 Cyclopolymerization 112

Chapter 5: Anionic Polymerizations

5.1 Introduction 116 5.2 Anionic Polymerizations Carried out in Protic Media 117

Table of Contents 11

5.2.1 Reaction Scheme 117 5.2.2 Kinetics 118 5.2.3 Molecular Weight Distribution of Polymers Obtained by Anionic

Polymerization in Protic Media 119 5.2.4 Ring Opening Polymerization in Protic Media 120 5.3 Anionic Polymerization in Aprotic Media: "Living" Polymers 121 5.3.1 Reaction Scheme 121 5.3.2 Kinetics and Molecular Weight Distribution of "Living" Polymers . 122 5.3.3 Monomers, Initiators and Solvents in Living Anionic Polymerizations 126 5.3.3.1 Monomers 126 5.3.3.2 Initiators: Metal Organic and Radical Anionic 126 5.3.3.3 Solvents 130 5.3.4 Specific Features of Anionic Polymerizations in Apolar Solvents .. 133 5.3.5 Specific Features of Anionic Polymerizations Carried out in Polar

Solvents 133 5.3.5.1 Ions and Ion Pairs 134 5.3.5.2 Contact and Solvent Separated Ion Pairs 136 5.3.6 Applications of Anionic "Living" Polymerizations 136 5.3.6.1 Protonation 137 5.3.6.2 ю-Functional and aca-difunctional Polymers 137 5.3.6.3 Block Copolymers 138 5.3.6.4 Graft Copolymers 138 5.3.6.5 Networks 139 5.4 Stereoelective Polymerizations 139

Chapter 6: Cationic Polymerizations 6.1 Introduction 144 6.2 Cationic Polymerization of Vinylic Monomers 145 6.2.1 Initiators and Initiating Reactions 145 6.2.2 Propagation Reaction 146 6.2.3 Transfer and Termination Reactions 147 6.2.4 Kinetic Expressions for Cationic Polymerizations 149 6.2.5 Polyisobutene and Butyl Rubber 152 6.2.6 Inifer Processes 152 6.3 Cationic Polymerization of Heterocycles 154 6.3.1 Initiation 154 6.3.2 Propagation 156 6.3.3 Transfer and Termination 156 6.3.4 "Living" Cationic Ring Opening Polymerizations 157 6.3.5 Some Specific Cases 158 6.3.6 Other Ring Opening Polymerizations 160 6.3.6.1 Polyphosphonitrilic Chloride (Polyphosphazenes) 160 6.3.6.2 Polydimethylsiloxanes 160


Chapter 7: Special Features of Ionic and Pseudo-Ionic Polymerizations

7.1 Propagation-Depropagation Equilibria 164 7.1.1 General 164 7.1.2 Kinetics and Thermodynamics of Reversible Propagation 165 7.1.3 Influence of the Reversibility of Chain Growth on the Molecular

Weight Distribution 167 7.1.4 Consequences of the Reversibility of the Propagation Step 170 7.2 Polymerization Processes Involving Dipole-Dipole Interactions 171 7.2.1 "Living" Cationic Polymerization of Vinylic or Vinylenic Monomers 171 7.2.2 Group Transfer Polymerization 173 7.3 Activated Monomer Polymerizations 175 7.3.1 Anionic "Activated Monomer" Polymerizations 175 7.3.2 Cationic "Activated Monomer" Polymerizations 177 7.4 Rationalization of Polymerization Processes Involving Ions or

Dipoles 178

Chapter 8: Polymerizations Involving Stereoregulation

8.1 Introduction 182 8.2 Ziegler-Natta Polymerizations 183 8.3 Mechanisms Involved in Ziegler-Natta Polymerizations 186 8.4 Kinetics of Ziegler-Natta Polymerizations 188 8.5 Ziegler-Natta Ring Opening Polymerizations 191 8.6 Ziegler-Natta Copolymerization Reactions 192 8.7 Applications of Ziegler-Natta Polymerizations 193 8.8 Other Stereoregulating Catalyst Systems 194 8.9 Metathesis Polymerizations 195

Chapter 9: Chemical Reactions on Polymers

9.1 Introduction 198 9.2 Chemical Reactions Involving the Backbone Chain 200 9.2.1 Oxydative Degradation 200 9.2.2 Chain Unzipping 202 9.2.3 Cleavage by Ozone 202 9.2.4 Periodic Acid Cleavage 202 9.2.5 Free Radical Crosslinking 203 9.2.6 Vulcanization of Elastomers 203 9.3 Chemical Reactions Involving the Functions 204 9.3.1 Kinetic Aspects of the Chemical Modification of Polymers 204 9.3.2 Cyclization Reactions 206 9.3.3 Examples of Chemical Reactions Affecting the Substituents of a

Polymer Chain 209 9.3.3.1 Addition Reactions 209 9.3.3.2 Elimination Reactions 209 9.3.3.3 Substitution Reactions 210

Table of Contents 13

Chapter 10: Functional Polymers, Block and Graft Copolymers, Model Networks

10.1 Introduction 218 10.2 Functional Polymers 219 10.2.1 Functionalization by Step Growth Polymerization 219 10.2.2 Functionalization by Free Radical Polymerization 219 10.2.2.1 Functional Initiators 220 10.2.2.2 Functionalization by Transfer Processes 220 10.2.2.3 Telomerizations 221 10.2.3 Functionalization by Anionic Polymerization 222 10.2.4 Functionalization by Cationic Polymerization 222 10.3 Block Copolymers 223 10.3.1 Block Copolymers by Free Radical Copolymerization Techniques.. 223 10.3.2 Block Copolymers by Anionic Living Polymerization Techniques .. 224 10.3.3 Other Techniques to Synthesize Block Copolymers 226 10.3.3.1 Cationic Polymerization 226 10.3.3.2 Site Transformation Tfechniques 227 10.3.3.3 Coupling between Preformed Functional Blocks 228 10.4 Graft Copolymer Synthesis 229 10.4.1 "Grafting from" Methods 229 10.4.2 "Grafting onto" Methods 230 10.4.3 Graft Copolymer Synthesis via Macromonomers 231 10.5 Network Formation 233 10.5.1 General Methods - Random Crosslinking 233 10.5.2 End-Linking Methods 234

Part- II: Reactors and Processes for Manufacturing Polymers Chapter 11: Interrelationships of Polymer Structure, Chemistry of Synthesis, and

Process Engineering

11.1 Product Definition: Choice of Chemical Route: Engineering Decisions 237

11.2 Physical Properties: Variation as Monomer is Converted to Polymer 239 11.3 Engineering Decisions Regarding Process and Reactor 242

Chapter 12: Emulsion and Suspension Polymerization

12.1 Emulsion Polymerization 248 12.1.1 Introduction 248 12.1.2 Advantages and Disadvantages 250 12.1.3 Initiators 251 12.1.4 Smith-Ewart Kinetic Scheme 252 12.1.5 Rate of Conversion According to Stage 254 12.1.6 Multiple Radical Effects in Emulsion Polymerization 257 12.1.7 Emulsion Copolymerization 259


12.1.8 Anomalous Emulsion Polymerization 260 12.2 Suspension Polymerization 260 12.2.1 Introduction 260 12.2.2 Problems of Fluid Mechanics 261 12.2.3 Preferred Sequence of Operations 262 12.2.4 Special Bead Polymerized Materials 263

Chapter 13: Heterogeneous Polymerizations and Interfacial Reactions 13.1 Introduction 267 13.2 Polymerization of Monomer without Solvent Resulting in a "Precipi

tated" Polymer 267 13.3 Polymerization of Monomer in a Solvent which Causes "Precipita

tion" of the Polymer 272 13.4 Polymerizations with Particulate Stereoregulating Catalysts 274 13.4.1 Introduction 274 13.4.2 Micromolecules, Macromolecules and Heterogeneous Catalysts . . . 275 13.4.3 Polymerizations by Heterogeneous Catalysts with Continuous Liquid

Phase 277 13.4.4 Polymerization by Heterogeneous Catalysts in a Gas Fluidized Bed 279 13.5 Interfacial Polymerization and Interfacial Reactions 280 13.5.1 Introduction 280 13.5.2 Polymer Formation at an Interfacial Zone Between Two Immiscible

Phases Each Containing a Reagent Monomer 281 13.5.3 Reactions on Polymers at Interfacial Zones 284 13.5.3.1 Hydrolysis of Xanthate Cellulose 284 13.5.3.2 Hydrolysis of Poly(methyl acrylate) Presented as Cross-Linked Beads 284

Appendices: Examples of Polymerization or Cross-Linking Processes in Reactors which Impart Special Shape

A.l Soft Contact Lens: Hydroxyethylmethacrylate 288 A.2 Unsaturated Polyester-Styrene Reinforced with Glass Fiber 289 A.3 Laminates from Epoxy Resins Reinforced with Fabrics 290 A.4 Reaction Injection Molding of Polyurethanes 292 A.5 Reaction Injection Molding of Nylon-6 293 A.6 Polymethacrylate Formed into Tube, Rod, Sheet 294 В High Pressure Radical Polymerization of Ethylene 295

Solutions of the Problems 298

Bibliography 334

Polymer Synthesis - GBV

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