Colloid Science Principles, methods and applications

Transcription

1 Colloid Science Principles, methods and applications Second Edition Edited by TERENCE COSGROVE School of Chemistry, University of Bristol, Bristol, UK WILEY A John Wiley and Sons, Ltd, Publication

2 Contents Preface Introduction Acknowledgements List of Contributors xv xvii xix xxi 1 An Introduction to Colloids 1 Roy Hughes 1.1 Introduction Basic Definitions Concentration Interfacial Area Effective Concentrations Average Separation Stability Quiescent Systems Sedimentation or Creaming Shearing Flows Other Forms of Instability Colloid Frontiers 18 References 20 2 Charge in Colloidal Systems 23 David Fermin and Jason Riley 2.1 Introduction The Origin of Surface Charge Ionisation of Surface Groups Ion Adsorption Dissolution of Ionic Solids Isomorphous Substitution Potential Determining Ions The Electrochemical Double Layer The Stern-Gouy-Chapman (SGC) Model of the Double Layer The Double Layer at the Hg/Electrolyte Interface Specific Adsorption Interparticle Forces 36

3 v/77 Contents 2.4 Electrokinetic Properties Electrolyte Flow Streaming Potential Measurements Electro-osmosis Electrophoresis Electroacoustic Technique 42 References 42 3 Stability of Charge-stabilised Colloids 45 John Eastman 3.1 Introduction The Colloidal Pair Potential Attractive Forces Electrostatic Repulsion Effect of Particle Concentration Total Potential Criteria for Stability Salt Concentration Counter-ion Valency Zeta Potential Particle Size Kinetics of Coagulation Diffusion-limited Rapid Coagulation Interaction-limited Coagulation ExperimentalDeterminationofc.ee Conclusions 58 References 59 4 Surfactant Aggregation and Adsorption at Interfaces 61 Julian Eastoe 4.1 Introduction Characteristic Features of Surfactants Classification and Applications of Surfactants Types of Surfactants Surfactant Uses and Development Adsorption of Surfactants at Interfaces Surface Tension and Surface Activity Surface Excess and Thermodynamics of Adsorption Efficiency and Effectiveness of Surfactant Adsorption Surfactant Solubility The Krafft Temperature The Cloud Point Micellisation Thermodynamics of Micellisation 75

4 Contents ix Factors Affecting the CMC Structure of Micelles and Molecular Packing Liquid Crystalline Mesophases Definition Structures Phase Diagrams Advanced Surfactants 87 References 88 Microemulsions 91 Julian Eastoe 5.1 Introduction Microemulsions: Definition and History Theory of Formation and Stability Interfacial Tension in Microemulsions Kinetic Instability Physicochemical Properties Predicting Microemulsion Type Surfactant Film Properties Phase Behaviour Developments and Applications Microemulsions with Green and Novel Solvents Microemulsions as Reaction Media for Nanoparticles 113 References 114 Emulsions Brian Vincent 6.1 Introduction Definitions of Emulsion Type Novel Features of Emulsion Systems, Compared to Solid/Liquid Dispersions 6.2 Preparation Stability References Comminution - Batch Comminution - Continuous Nucleation and Growth Introduction Sedimentation and Creaming Aggregation Coalescence Ostwald Ripening Phase Inversion

5 x Contents Polymers and Polymer Solutions 135 Terence Cosgrove 7.1 Introduction Polymerisation Condensation Free Radical Ionic Methods Copolymers Polymer Physical Properties Entanglements Polymer Uses Theoretical Models of Polymer Structure Radius of Gyration Worm-like Chains Radius of Gyration in Ideal Solution Excluded Volume Scaling Theory: Blobs Polyelectrolytes Measuring Polymer Molecular Weight Viscosity Flory-Huggins Theory Polymer Solutions Polymer Melts Copolymers 150 References 150 Polymers at Interfaces 151 Terence Cosgrove 8.1 Introduction Steric Stability The Size and Shape of Polymers in Solution Adsorption of Small Molecules Adsorption of Polymers Configurational Entropy The Flory Surface Parameter ^s Models and Simulations for Terminally Attached Chains Atomistic Modelling Exact Enumeration: Terminally Attached Chains Approximate Methods: Terminally Attached Chains Scaling Models for Terminally Attached Chains (Brushes) Physically Adsorbed Chains: Scheutjens and Fleer Theory Scaling Theory for Physical Adsorption Experimental Aspects Volume Fraction Profiles Adsorption Isotherms 167

6 Contents xi The Bound Fraction The Layer Thickness Copolymers Liquid/Liquid Interfaces Polymer Brushes Conclusions 179 References Effect of Polymers on Colloid Stability 181 Jeroen van Duijneveldt 9.1 Introduction Colloid Stability Limitations of Charge Stabilisation Effect of Polymers on Interactions Particle Interaction Potential Measuring Surface Forces Steric Stabilisation Theory Steric Stabiliser Design Marginal Solvents Depletion Interactions Bridging Interactions Conclusion 193 References Wetting of Surfaces 197 Paul Reynolds 10.1 Introduction Surfaces and Definitions Surface Tension Surface Energy Contact Angles Wetting Liquid Spreading and Spreading Coefficients Cohesion and Adhesion Two Liquids on a Surface Detergency Spreading of a Liquid on a Liquid Characterisation of a Solid Surface Polar and Dispersive Components Polar Materials Wettability Envelopes Measurement Methods Conclusions 216 References 216

7 Contents Aerosols 219 Nana-Owusua A. Kwamena and Jonathan P. Reid 11.1 Introduction Generating and Sampling Aerosols Generating Aerosols Sampling Aerosol Determining the Particle Concentration and Size Determining the Number Concentration Determining the Mass Concentration Determining Particle Size Determining Particle Composition Off-line Analysis Real-time Analysis The Equilibrium State of Aerosols Deliquescence and Efflorescence Köhler Theory Measurements of Hygroscopic Growth Other Phases The Kinetics of Aerosol Transformation Steady and Unsteady Mass and Heat Transfer Uptake of Trace Species and Heterogeneous Chemistry Concluding Remarks 242 References 242 Practical Rheology Roy Hughes Introduction Making Measurements Definitions Designing an Experiment Geometries Viscometry Shear Thinning and Thickening Behaviour Rheometry and Viscoelasticity Viscoelasticity and Deborah Number Oscillation and Linearity Creep Compliance Liquid and Solid Behaviour Sedimentation and Storage Stability Examples of Soft Materials Simple Particles and Polymers Networks and Functionalisation Polymeric Additives Particle Additives Summary 271 References

8 Contents xiii 13 Scattering and Reflection Techniques 273 Robert Richardson 13.1 Introduction The Principle of a Scattering Experiment Radiation for Scattering Experiments Light Scattering Dynamic Light Scattering Small Angle Scattering Sources of Radiation Small Angle Scattering Apparatus Scattering and Absorption by Atoms Scattering Length Density Small Angle Scattering from a Dispersion Form Factor for Spherical Particles Determining Particle Size from SANS and SAXS Guinier Plots to Determine Radius of Gyration Determination of Particle Shape Polydispersity Determination of Particle Size Distribution Alignment of Anisotropic Particles Concentrated Dispersions Contrast Variation Using SANS High Q Limit: Porod Law Introduction to X-Ray and Neutron Reflection Reflection Experiment A Simple Example of a Reflection Measurement Conclusion 297 References Optical Manipulation 299 Paul Bartlett 14.1 Introduction Manipulating Matter with Light Force Generation in Optical Tweezers Nanofabrication Single Particle Dynamics Measuring Nanometer Displacements Brownian Fluctuations in an Optical Trap Dynamical Complexity in Colloidal Gels Conclusions 308 References Electron Microscopy 311 Sean Davis 15.1 General Features of (Electron) Optical Imaging Systems 311

9 xiv Contents 15.2 Conventional ТЕМ Background Practical Aspects Polymer Latex Particles Core/Shell Particles Internal Structure Conventional SEM Background Types of Signal Practical Aspects Summary 327 References Surface Forces 329 Wuge Briscoe 16.1 Introduction Intermolecular Forces From Intermolecular Forces to Surface Forces Why Measure Surface Forces? Forces and Energy; Size and Shape Pressure, Force and Energy The Derjaguin Approximation Surface Force Measurement Techniques Optical Tweezers Total Internal Reflection Microscopy (TIRM) Atomic Force Microscope (AFM) Surface Force Apparatus (SFA) Other Techniques Different Types of Surface Forces van der Waals Forces Electric Double Layer Forces in a Polar Liquid The DLVO Theory Non-DLVO Forces Neutral Polymer-mediated Surface Forces Surface Forces in Surfactant Solutions Recent Examples of Surface Force Measurement Counter-ion Only (CIO) Electric Double Layer Interactions in a Non-polar Liquid Interactions Between Surface-grown Biomimetic Polymer Brushes in Aqueous Media Boundary Lubrication Under Water Future Challenges 360 References 361 Index 363