Colloid science : principles, methods and applications

Colloidal systems are important across a range of industries, such as the food, pharmaceutical, agrochemical, cosmetics, polymer, paint and oil industries, and form the basis of a wide range of products (eg cosmetics & toiletries, processed foodstuffs and photographic film). A detailed understanding of their formation, control and application is required in those industries, yet many new graduate or postgraduate chemists or chemical engineers have little or no direct experience of colloids.Based on lectures given at the highly successful Bristol Colloid Centre Spring School, Colloid Science: Principles, Methods and Applications provides a thorough introduction to colloid science for industrial chemists, technologists and engineers. Lectures are collated and presented in a coherent and logical text on practical colloid science. Colloid Science Principles, methods and applications......Page 1 Contents......Page 9 Preface......Page 17 Introduction......Page 19 Acknowledgements......Page 21 List of Contributors......Page 23 1.1 Introduction......Page 25 1.2.1 Concentration......Page 29 1.2.2 Interfacial Area......Page 34 1.2.3 Effective Concentrations......Page 35 1.2.4 Average Separation......Page 36 1.3 Stability......Page 38 1.3.1 Quiescent Systems......Page 39 1.3.2 Sedimentation or Creaming......Page 40 1.3.4 Other Forms of Instability......Page 41 1.4 Colloid Frontiers......Page 42 References......Page 44 2.1 Introduction......Page 47 2.2.1 Ionisation of Surface Groups......Page 48 2.2.5 Potential Determining Ions......Page 49 2.3.1 The Stern–Gouy–Chapman (SGC) Model of the Double Layer......Page 50 2.3.2 The Double Layer at the Hg/Electrolyte Interface......Page 54 2.3.3 Specific Adsorption......Page 58 2.4.1 Electrolyte Flow......Page 60 2.4.2 Streaming Potential Measurements......Page 61 2.4.3 Electro-osmosis......Page 62 2.4.4 Electrophoresis......Page 63 References......Page 66 3.1 Introduction......Page 69 3.2.1 Attractive Forces......Page 70 3.2.2 Electrostatic Repulsion......Page 71 3.2.3 Effect of Particle Concentration......Page 73 3.2.4 Total Potential......Page 74 3.3.1 Salt Concentration......Page 75 3.3.2 Counter-ion Valency......Page 76 3.3.4 Particle Size......Page 78 3.4.1 Diffusion-limited Rapid Coagulation......Page 79 3.4.2 Interaction-limited Coagulation......Page 80 3.4.3 Experimental Determination of c.c.c.......Page 81 3.5 Conclusions......Page 82 References......Page 83 4.2 Characteristic Features of Surfactants......Page 85 4.3.1 Types of Surfactants......Page 86 4.3.2 Surfactant Uses and Development......Page 88 4.4.1 Surface Tension and Surface Activity......Page 90 4.4.2 Surface Excess and Thermodynamics of Adsorption......Page 91 4.4.3 Efficiency and Effectiveness of Surfactant Adsorption......Page 95 4.5.1 The Krafft Temperature......Page 97 4.5.2 The Cloud Point......Page 98 4.6.1 Thermodynamics of Micellisation......Page 99 4.6.2 Factors Affecting the CMC......Page 102 4.6.3 Structure of Micelles and Molecular Packing......Page 104 4.7.1 Definition......Page 106 4.7.2 Structures......Page 107 4.7.3 Phase Diagrams......Page 110 4.8 Advanced Surfactants......Page 111 References......Page 112 5.2 Microemulsions: Definition and History......Page 115 5.3.1 Interfacial Tension in Microemulsions......Page 117 5.4.1 Predicting Microemulsion Type......Page 119 5.4.2 Surfactant Film Properties......Page 125 5.4.3 Phase Behaviour......Page 131 5.5.1 Microemulsions with Green and Novel Solvents......Page 134 5.5.2 Microemulsions as Reaction Media for Nanoparticles......Page 137 References......Page 138 6.1.1 Definitions of Emulsion Type......Page 141 6.2.1 Comminution – Batch......Page 144 6.2.3 Nucleation and Growth......Page 148 6.3.2 Sedimentation and Creaming......Page 150 6.3.3 Aggregation......Page 151 6.3.4 Coalescence......Page 152 6.3.5 Ostwald Ripening......Page 154 6.3.6 Phase Inversion......Page 155 References......Page 157 7.2 Polymerisation......Page 159 7.2.2 Free Radical......Page 160 7.3 Copolymers......Page 161 7.6 Theoretical Models of Polymer Structure......Page 162 7.6.1 Radius of Gyration......Page 163 7.6.2 Worm-like Chains......Page 165 7.6.4 Excluded Volume......Page 166 7.6.5 Scaling Theory: Blobs......Page 167 7.7 Measuring Polymer Molecular Weight......Page 168 7.8.1 Polymer Solutions......Page 170 References......Page 174 8.1 Introduction......Page 175 8.1.2 The Size and Shape of Polymers in Solution......Page 176 8.1.3 Adsorption of Small Molecules......Page 178 8.2.2 The Flory Surface Parameter ws......Page 179 8.3.1 Atomistic Modelling......Page 180 8.3.2 Exact Enumeration: Terminally Attached Chains......Page 181 8.3.4 Scaling Models for Terminally Attached Chains (Brushes)......Page 184 8.3.5 Physically Adsorbed Chains: Scheutjens and Fleer Theory......Page 185 8.3.6 Scaling Theory for Physical Adsorption......Page 189 8.4.1 Volume Fraction Profiles......Page 190 8.4.2 Adsorption Isotherms......Page 191 8.4.3 The Bound Fraction......Page 194 8.4.4 The Layer Thickness......Page 195 8.5 Copolymers......Page 199 8.5.1 Liquid/Liquid Interfaces......Page 200 8.6 Polymer Brushes......Page 201 8.7 Conclusions......Page 203 References......Page 204 9.1.1 Colloid Stability......Page 205 9.2 Particle Interaction Potential......Page 206 9.3.1 Theory......Page 207 9.3.2 Steric Stabiliser Design......Page 210 9.3.3 Marginal Solvents......Page 211 9.4 Depletion Interactions......Page 213 9.5 Bridging Interactions......Page 216 9.6 Conclusion......Page 217 References......Page 218 10.1 Introduction......Page 221 10.3 Surface Tension......Page 222 10.5 Contact Angles......Page 223 10.6 Wetting......Page 224 10.7 Liquid Spreading and Spreading Coefficients......Page 226 10.8 Cohesion and Adhesion......Page 227 10.9 Two Liquids on a Surface......Page 228 10.11 Spreading of a Liquid on a Liquid......Page 231 10.13 Polar and Dispersive Components......Page 234 10.14 Polar Materials......Page 235 10.15 Wettability Envelopes......Page 236 10.16 Measurement Methods......Page 238 References......Page 240 11.1 Introduction......Page 243 11.2.1 Generating Aerosols......Page 246 11.2.2 Sampling Aerosol......Page 248 11.3 Determining the Particle Concentration and Size......Page 249 11.3.2 Determining the Mass Concentration......Page 250 11.3.3 Determining Particle Size......Page 251 11.4.1 Off-line Analysis......Page 254 11.4.2 Real-time Analysis......Page 255 11.5.1 Deliquescence and Efflorescence......Page 258 11.5.2 K€ohler Theory......Page 259 11.5.3 Measurements of Hygroscopic Growth......Page 261 11.6 The Kinetics of Aerosol Transformation......Page 262 11.6.1 Steady and Unsteady Mass and Heat Transfer......Page 263 11.6.2 Uptake of Trace Species and Heterogeneous Chemistry......Page 264 References......Page 266 12.2 Making Measurements......Page 269 12.2.1 Definitions......Page 270 12.2.2 Designing an Experiment......Page 272 12.2.3 Geometries......Page 274 12.2.4 Viscometry......Page 276 12.2.5 Shear Thinning and Thickening Behaviour......Page 278 12.3.1 Viscoelasticity and Deborah Number......Page 280 12.3.2 Oscillation and Linearity......Page 281 12.3.3 Creep Compliance......Page 282 12.3.4 Liquid and Solid Behaviour......Page 283 12.3.5 Sedimentation and Storage Stability......Page 285 12.4 Examples of Soft Materials......Page 287 12.4.1 Simple Particles and Polymers......Page 288 12.4.2 Networks and Functionalisation......Page 291 12.4.4 Particle Additives......Page 292 12.5 Summary......Page 295 References......Page 296 13.1 Introduction......Page 297 13.2 The Principle of a Scattering Experiment......Page 298 13.3 Radiation for Scattering Experiments......Page 299 13.4 Light Scattering......Page 300 13.5 Dynamic Light Scattering......Page 302 13.7 Sources of Radiation......Page 303 13.8 Small Angle Scattering Apparatus......Page 304 13.9 Scattering and Absorption by Atoms......Page 306 13.10 Scattering Length Density......Page 307 13.11 Small Angle Scattering from a Dispersion......Page 308 13.13 Determining Particle Size from SANS and SAXS......Page 309 13.15 Determination of Particle Shape......Page 310 13.16 Polydispersity......Page 311 13.17 Determination of Particle Size Distribution......Page 312 13.19 Concentrated Dispersions......Page 313 13.20 Contrast Variation using SANS......Page 314 13.21 High Q Limit: Porod Law......Page 316 13.22 Introduction to X-ray and Neutron Reflection......Page 318 13.24 A Simple Example of a Reflection Measurement......Page 319 References......Page 321 14.2 Manipulating Matter with Light......Page 323 14.3 Force Generation in Optical Tweezers......Page 326 14.4 Nanofabrication......Page 328 14.5.1 Measuring Nanometer Displacements......Page 329 14.5.2 Brownian Fluctuations in an Optical Trap......Page 330 14.5.3 Dynamical Complexity in Colloidal Gels......Page 331 References......Page 332 15.1 General Features of (Electron) Optical Imaging Systems......Page 335 15.2.1 Background......Page 337 15.2.2 Practical Aspects......Page 338 15.2.3 Polymer Latex Particles......Page 339 15.2.4 Core/Shell Particles......Page 340 15.2.5 Internal Structure......Page 341 15.3.3 Practical Aspects......Page 345 References......Page 351 16.1.1 Intermolecular Forces......Page 353 16.1.2 From Intermolecular Forces to Surface Forces......Page 354 16.1.3 Why Measure Surface Forces?......Page 357 16.2.1 Pressure, Force and Energy......Page 358 16.2.2 The Derjaguin Approximation......Page 359 16.3.1 Optical Tweezers......Page 363 16.3.3 Atomic Force Microscope (AFM)......Page 364 16.3.5 Other Techniques......Page 365 16.4 Different Types of Surface Forces......Page 366 16.4.1 van der Waals Forces......Page 367 16.4.2 Electric Double Layer Forces in a Polar Liquid......Page 368 16.4.4 Non-DLVO Forces......Page 369 16.4.5 Neutral Polymer-mediated Surface Forces......Page 376 16.4.6 Surface Forces in Surfactant Solutions......Page 379 16.5 Recent Examples of Surface Force Measurement......Page 380 16.5.1 Counter-Ion Only (CIO) Electric Double Layer Interactions in a Non-Polar Liquid......Page 381 16.5.3 Boundary Lubrication Under Water......Page 382 16.6 Future Challenges......Page 384 References......Page 385 Index......Page 387 Colloidal systems are important across a range of industries, such as the food, pharmaceutical, agrochemical, cosmetics, polymer, paint and oil industries, and form the basis of a wide range of products (eg cosmetics & toiletries, processed foodstuffs and photographic film). A detailed understanding of their formation, control and application is required in those industries, yet many new graduate or postgraduate chemists or chemical engineers have little or no direct experience of colloids. Based on lectures given at the highly successful Bristol Colloid Centre Spring School, Colloid Science