Principles and Applications of Emulsion Polymerization / Edition 1

by Chorng-Shyan Chern

Overview

Up-to-date coverage of methods of emulsion polymerization

This book provides a comprehensive reference on emulsion polymerization methods,focusing on the fundamental mechanisms and kinetics of each process, as well as howthey can be applied to the manufacture of environmentally friendly polymeric materials.

Topics covered include:

• Conventional emulsion polymerization
• Miniemulsion polymerization
• Microemulsion polymerization
• Industrial emulsion polymerization processes (primarily the semibatch and continuous reactions systems)
• The role of various colloidal phenomena in emulsion polymerization
• Important end-use properties of emulsion polymer (latex) products
• Information on industrial applications in paints, coatings, adhesives, paper and board, and more

This is a hands-on reference for graduate students and professionals in polymerchemistry, chemical engineering, and materials science who are involved in researchon coatings, adhesives, rubber, latex, paints, finishes, and other materials that can becreated using various methods of emulsion polymerization.

Product Details

ISBN-13:	9780470124314
Publisher:	Wiley
Publication date:	08/04/2008
Pages:	272
Product dimensions:	6.30(w) x 9.30(h) x 0.70(d)

About the Author

Chorng-Shyan Chern, PhD, is Professor in the Department of Chemical Engineering at the National Taiwan University of Science and Technology in Taipei. He received his PhD from the Georgia Institute of Technology, and was associated with United Merchants, S.C. Johnson Wax, and Union Carbide during his industrial career. His major research interests involve nucleation, growth, and stability of latex particles during emulsion polymerization.

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Table of Contents

Preface xi

1 Introduction 1

1.1 Free Radical Polymerization 1

1.1.1 Free Radical Polymerization Mechanisms 1

1.1.2 Free Radical Polymerization Kinetics 3

1.2 Emulsion Polymerization 5

1.2.1 Conventional Emulsion Polymerization 5

1.2.2 Emulsion Polymerization Processes 6

1.2.3 Miniemulsion Polymerization 8

1.2.4 Microemulsion Polymerization 9

1.2.5 Inverse Emulsion Polymerization 10

1.3 Colloidal Stability 11

1.3.1 A Critical but Often Ignored Issue 11

1.3.2 Electrostatic Interactions 12

1.3.3 Steric Interactions 13

1.3.4 Mechanical Stability 14

1.4 Some Performance Properties for Industrial Applications 15

1.4.1 Rheology 15

1.4.2 Film Formation 16

References 19

2 Interfacial Phenomena 23

2.1 Thermodynamic Consideration 23

2.1.1 Emulsification of Oil in Water 23

2.1.2 Interfaces 25

2.1.3 Surfactant Molecules Adsorbed at an Interface 26

2.2 Surfactants 26

2.2.1 Critical Micelle Concentration (CMC) 27

2.2.2 Hydrophile-Lipophile Balance (HLB) 27

2.2.3 Solubility Parameter 29

2.3 Colloidal Stability 32

2.3.1 Van der Waals Forces 32

2.3.2 Electrostatic Interactions 36

2.3.3 Steric Interactions 44

2.3.4 Kinetics of Flocculation 48

References 50

3 Particle Nucleation Mechanisms 53

3.1 Micellar Nucleation 54

3.1.1 Harkins-Smith-Ewart Theory 54

3.1.2 Competitive Absorption of Free Radicals by Micelles and Particle Nuclei 57

3.2 Homogeneous Nucleation 60

3.2.1 Formation of Particle Nuclei in the Continuous Aqueous Phase 60

3.2.2 Hansen-Ugelstad-Fitch-Tsai (HUFT) Model 63

3.3 Coagulative Nucleation 65

3.3.1 General Features of Coagulative Nucleation 65

3.3.2 Coagulative Nucleation Model Development 66

3.4 Mixed Mode of Particle Nucleation Mechanisms 68

3.5 Surfactant-Free Emulsion Polymerization 71

3.6 Experimental Work on Particle Nucleation 76

3.6.1 A Dilemma about Particle Nucleation Mechanisms 76

3.6.2 Some Representative Experimental Data of Particle Nucleation 77

3.6.3 Some Potential Techniques for Studying Particle Nucleation 82

3.6.4 Effects of Surfactant Concentration on Particle Nucleation 86

3.7 Nonionic and Mixed Surfactant Systems 87

3.7.1 Nonionic Surfactant Systems 88

3.7.2 Mixed Anionic and Nonionic Surfactant Systems 89

References 91

4 Emulsion Polymerization Kinetics 95

4.1 Emulsion Polymerization Kinetics 96

4.1.1 Smith-Ewart Theory 96

4.1.2 Pioneering Kinetic Models for Predicting Average Number of Free Radicals per Particle 100

4.2 Absorption of Free Radicals by Latex Particles 103

4.2.1 Collision- and Diffusion-Controlled Models 104

4.2.2 Propagation-Controlled Model 106

4.2.3 Some Controversial Issues 108

4.3 Desorption of Free Radicals Out of Latex Particles 109

4.3.1 Desorption of Free Radicals in Emulsion Homopolymerization Systems 110

4.3.2 Desorption of Free Radicals in Emulsion Copolymerization Systems 112

4.3.3 Effect of Interfacial Properties on Desorption of Free Radicals 113

4.4 Growth of Latex Particles 114

4.4.1 Thermodynamic Consideration 114

4.4.2 Concentrations of Comonomers in Emulsion Copolymerization Systems 116

4.4.3 Competitive Growth of Latex Particles 119

4.5 Polymer Molecular Weight 120

References 123

5 Miniemulsion Polymerization 128

5.1 Polymerization in Monomer Droplets 129

5.2 Stability of Monomer Emulsions 130

5.2.1 Ostwald Ripening Effect 130

5.2.2 Role of Costabilizer in Stabilizing Monomer Emulsions 132

5.3 Type of Costabilizers in Miniemulsion Polymerization 133

5.4 Miniemulsion Polymerization Mechanisms and Kinetics 135

5.4.1 Initial Conditions for Miniemulsion Polymerization Systems 135

5.4.2 Particle Nucleation Mechanisms 136

5.4.3 Effect of Functional Monomers and Initiators on Particle Nucleation 140

5.4.4 Polymerization Kinetics 142

5.5 Versatility of Miniemulsion Polymerization 145

5.5.1 Catalytic Chain Transfer Reaction 147

5.5.2 Living Free Radical Polymerization 147

5.5.3 Step Polymerization 148

References 150

6 Microemulsion Polymerization 154

6.1 Introduction 154

6.2 Formation and Microstructure of Microemulsions 155

6.2.1 Formation of Microemulsions 155

6.2.2 Factors that Govern Microemulsion Structures 157

6.3 O/W Microemulsion Polymerization 158

6.3.1 General Features 158

6.3.2 Polymerization Mechanisms and Kinetics 159

6.4 W/O Microemulsion Polymerization 167

6.5 Polymerization in Continuous or Bicontinuous Phases of Microemulsions 169

References 170

7 Semibatch and Continuous Emulsion Polymerizations 175

7.1 Semibatch Emulsion Polymerization 175

7.1.1 Pseudo-Steady-State Polymerization Behavior 175

7.1.2 Polymerization Mechanisms and Kinetics 177

7.1.3 Mathematical Modeling Studies 186

7.2 Continuous Emulsion Polymerization 187

7.2.1 General Features of Continuous Emulsion Polymerization Processes 187

7.2.2 Particle Nucleation and Growth Mechanisms 191

7.3 Development of Commercial Continuous Emulsion Polymerization Processes 194

References 196

8 Emulsion Polymerizations in Nonuniform Latex Particles 200

8.1 Origin of Nonuniform Latex Particles 200

8.2 Seeded Emulsion Polymerizations 201

8.3 Factors Affecting Particle Morphology 202

8.3.1 Effect of Initiators 202

8.3.2 Effect of Monomer Addition Methods 203

8.3.3 Effect of Polymer Molecular Weight 204

8.3.4 Effect of Volume Fractions of Polymer Pairs 205

8.3.5 Effect of Polymerization Temperature 205

8.4 Morphology Development in Latex Particles 205

8.4.1 Thermodynamic Considerations 205

8.4.2 Nonequilibrium Morphology Development 206

8.4.3 Techniques for Characterization of Particle Morphology 210

8.5 Polymerization Kinetics in Nonuniform Latex Particles 211

8.5.1 Pioneering Studies 212

8.5.2 Effect of Distribution of Free Radicals in Nonuniform Latex Particles 213

References 220

9 Applications of Emulsion Polymers 223

9.1 Physical Properties of Emulsion Polymers 224

9.1.1 Effect of Polymer Molecular Weight 224

9.1.2 Effect of Polymer Morphology 225

9.1.3 Effect of Crosslinking Reactions 229

9.2 Rheological Properties of Emulsion Polymers 230

9.3 Film Formation of Emulsion Polymers 233

9.4 Foaming and Antifoaming Agents 236

9.5 Wetting 238

9.6 Surface Modifications 241

9.7 Stability of Latex Products 242

References 245

Index 248