Colloids and Interfaces with Surfactants and Polymers An Introduction Colloids and Interfaces with Surfactants and Polymers An Introduction J. W. Goodwin ß 2004 John Wiley & Sons, Ltd ISBN: 0-470-84142-7 (HB) ISBN: 0-470-84143-5 (PB)
Scanning electron micrographs of some colloidal particles: (a) A film of printing ink showing well-dispersed titanium dioxide pigment (3400). (b) Sodium kaolinite (china clay) particles in an open card-house aggregate (9100). (c) Dried polystyrene latex showing how the order in a concentrated dispersion is maintained on drying (9100). (d) Coagulated bimodal latex mixture after shear processing showing densely packed, uniform aggregates (700). Reproduced with permission from Modern Aspects of Colloidal Dispersions edited by Ottewill and Rennie. Copyright (1998) Kluwer Academic Publishers.
Colloids and Interfaces with Surfactants and Polymers An Introduction Jim W. Goodwin Interfacial Dynamics Corporation Portland, Oregon, USA
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Contents Preface ix Chapter 1 The Nature of Colloids 1 1 INTRODUCTION 1 2 COLLOIDS IN ACTION 4 3 CONCENTRATED COLLOIDAL DISPERSIONS 8 4 INTERFACES 12 5 SURFACTANTS 20 6 SOLUTION POLYMERS 24 7 SUMMARY 25 REFERENCES 26 Chapter 2 Macromolecules and Surfactants 27 1 INTRODUCTION 27 2 MACROMOLECULAR DEFINITIONS 27 3 CONFORMATIONS IN DILUTE SOLUTIONS 29 4 THE FLORY HUGGINS THEORY OF POLYMER SOLUTIONS 32 5 POLYMER SOLUTION PHASE BEHAVIOUR 36 6 POLYMERS AT SURFACES 39 7 POLYMER CHARACTERIZATION 42 8 SURFACTANTS IN SOLUTION 46 REFERENCES 58 Chapter 3 Interactions between Colloidal Particles 61 1 INTRODUCTION 61 2 INTERMOLECULAR ATTRACTION 63 3 COMPLEX NUMBER MANIPULATION 68 4 DISPERSION FORCES BETWEEN PARTICLES 71 5 RETARDED DISPERSION FORCES 78 6 THE GENERAL OR LIFSHITZ THEORY OF DISPERSION FORCES BETWEEN PARTICLES 79 7 SUMMARY AND CALCULATION GUIDE 81
vi Colloids and Interfaces with Surfactants and Polymers 8 CALCULATION STRATEGY 82 9 THE DEPLETION INTERACTION 87 REFERENCES 93 Chapter 4 Forces of Repulsion 95 1 INTRODUCTION 95 2 ELECTROSTATIC INTERACTIONS 95 3 THE ORIGINS OF SURFACE CHARGE 96 4 THE INTERACTION BETWEEN DIFFUSE DOUBLE LAYERS 109 5 THE INTERACTION BETWEEN TWO SPHERES 112 6 THE EFFECT OF PARTICLE CONCENTRATION 114 7 STERIC INTERACTIONS 116 8 CALCULATION STRATEGY 123 REFERENCES 125 Chapter 5 The Stability of Dispersions 127 1 INTRODUCTION 127 2 THE STABILITY OF CHARGE-STABILIZED COLLOIDS THE DVLO THEORY 127 3 MECHANISMS OF AGGREGATION 129 4 HETERO-COAGULATION AND HETERO-FLOCCULATION 132 5 THE RATE OF COAGULATION 139 6 AGGREGATION IN FLOWING DISPERSIONS 143 REFERENCES 150 Chapter 6 The Wetting of Surfaces by Liquids 153 1 INTRODUCTION 153 2 THE CONTACT ANGLE 154 3 METHODS FOR THE MEASUREMENT OF CONTACT ANGLE 156 4 CONTACT ANGLE HYSTERESIS 158 5 SPREADING 160 6 CURVED SURFACES 164 7 CAPILLARITY 165 8 TEMPERATURE EFFECTS 171 REFERENCES 176 Chapter 7 Emulsions and Microemulsions 177 1 INTRODUCTION 177 2 EMULSIFICATION 178 3 STABILITY OF EMULSIONS 182 4 MICROEMULSIONS 187 REFERENCES 193
Contents vii Chapter 8 Characterization of Colloidal Particles 195 1 INTRODUCTION 195 2 PARTICLE SIZE 195 3 MICROSCOPY 198 4 ZONAL METHODS 201 5 SCATTERING METHODS 203 6 ANALYSIS OF SCATTERED RADIATION 206 7 NEUTRON REFLECTION 215 8 DYNAMIC LIGHT SCATTERING 216 9 CHARACTERIZATION OF THE ELECTRICAL PROPERTIES OF PARTICLES 218 10 VISCOSITIES OF DISPERSIONS 232 REFERENCES 238 Chapter 9 Concentrated Dispersions 241 1 INTRODUCTION 241 2 THE STRUCTURE OF CONCENTRATED DISPERSIONS 242 3 RHEOLOGY 247 4 LINEAR VISCOELASTICITY OF COLLOIDAL DISPERSIONS 257 5 PHENOMENOLOGY 259 REFERENCES 279 Index 281
Preface We take for granted the behaviour of colloidal systems from a very early age and as we are formerly taught the various scientific disciplines, the nature of colloids is rarely mentioned. This is surprising as it impacts on so many products that we use everyday. The processing and delivery of the correct properties is often dependent on the material being in the colloid state and yet few courses cover the subject in depth, if at all. As a result, many scientific workers have to acquire their knowledge piecemeal while working on other problems. An introductory text is what is most used in this situation. Specialist texts are often left on the shelf as we search for attempts to solve a particular problem. This present text covers a little more ground than some of the older introductory volumes that are still available but I have attempted to help the reader in the more complicated regions by providing a strategy for any calculations. Some derivations are outside the scope of an introduction, but, where they are straightforward, they are included in order to help readers gain as much insight as possible. None of the mathematics is at a high level. The references are mainly to specialist volumes in the area. This is not to discourage the reading of the original work but it is because the general volumes are more readily available in many libraries and often help to put the work in context. There will inevitably be some areas that are neglected, as with any introductory volume. This is in part due to what areas are perceived to be currently most generally needed and the composition of this volume has been governed by the questions which are currently asked when discussing problems in industry. I would like to acknowledge with gratitude the help and encouragement of all of my previous colleagues in the Department of Physical Chemistry at the University of Bristol, UK, especially Professors Ron Ottewill and Brian Vincent, the past and current holders of the Leverhulme Chair in that Department and also to Dr Paul Reynolds, the manager of the Bristol Colloid Centre. Jim Goodwin Portland, Oregon, 2003