Foundations of. Colloid Science SECOND EDITION. Robert J. Hunter. School of Chemistry University of Sydney OXPORD UNIVERSITY PRESS

Transcription

1 Foundations of Colloid Science SECOND EDITION Robert J. Hunter School of Chemistry University of Sydney OXPORD UNIVERSITY PRESS

2 CONTENTS 1 NATURE OF COLLOIDAL DISPERSIONS 1.1 Introduction Technological and biological significance of colloidal dispersions Classification of colloids Some typical colloidal dispersions б 1.5 Brownian motion and diffusion Electrical charge and colloid stability Effect of polymers on colloid stability 40 2 THERMODYNAMICS OF SURFACES 2.1 Introduction Surface energy and its consequences Thermodynamics of surfaces The Gibbs adsorption equation Thermodynamic behaviour of small particles Equilibrium shape of a crystal Behaviour of liquids in capillaries Homogeneous nucleation Limits of applicability of the Kelvin and Young-Laplace equations Contact angle and wetting behaviour Measurement of surface tension and contact angle RESPONSE TO EXTERNAL FIELDS AND STRESSES 3.1 Response to gravitational and centrifugal fields Response of a dielectric material to an electric field Response to electromagnetic (light) waves Response to a mechanical stress TRANSPORT PROPERTIES OF SUSPENSIONS 4.1 Introduction The mass conservation equation Stress in a moving fluid Stress and velocity field in a fluid in thermodynamic equilibrium Relationship between the stress tensor and the velocity field The Navier-Stokes equations Methods for measuring the viscosity Sedimentation of a suspension Brownian motion revisited The flow properties of suspensions 188

3 X I CONTENTS 5 PARTICLE SIZE AND SHAPE 5.1 General considerations Direct microscopic observation Particle size distribution Theoretical distribution functions Sedimentation methods of determining particle size Electrical pulse counters Light scattering methods Hydrodynamic methods Acoustic methods Summary of sizing methods ADSORPTION ONTO SOLID SURFACES 6.1 Vacuum characterization methods Some non-vacuum techniques Adsorption and desorption at the solid-gas interface Adsorption at the solid-liquid interface Adsorption of neutral polymers ELECTRIFIED INTERFACES: THE ELECTRICAL DOUBLE LAYER 7.1 The electrostatic potential of a phase The mercury-solution interface Potential distribution at a flat surface the Gouy-Chapman model Comparison with experiment Adsorption of (uncharged) molecules at the mercury-solution interface Limitations of the Poisson-Boltzmann equation The silver iodide-solution interface Other Nernstian surfaces Mechanisms of surface charge generation The double layer on oxide surfaces The double layer around a sphere The double layer around a cylinder ELECTROKINETICS AND THE ZETA POTENTIAL 8.1 Introduction Equilibrium double layer theory of electrokinetics Reciprocity relations The surface of shear Measuring electrokinetic properties Limitations of the elementary theory The standard double layer model Double layer dynamics Electrokinetic effects in thin double layer systems Numerical solutions of the linearized electrokinetic equations Electrokinetics in alternating fields Validity of the electrokinetic equations 426

4 CONTENTS I XI 9 ASSOCIATION COLLOIDS 9.1 The critical micellization concentration (c.m.c) Factors affecting the c.m.c Equilibrium constant treatment of micelle formation Thermodynamics of micelle formation Spectroscopic techniques for investigating micelle structure Micellar dynamics Molecular packing and its effect on aggregate formation Statistical thermodynamics of chain packing in micelles ADSORPTION AT CHARGED INTERFACES 10.1 Introduction Adsorption of potential determining ions Detection of Stern layer adsorption The oxide-solution interface Adsorption of multivalent ions Su rfacta nt adsorption THE THEORY OF VAN DER WAALS FORCES 11.1 Introduction London theory Pairwise summation of forces (Hamaker theory) Retardation effects in Hamaker theory The Deryaguin approximation Modern dispersion force theory Numerical computation of interaction energy Influence of electrolyte concentration Theoretical estimation of surface properties DOUBLE LAYER INTERACTION AND PARTICLE COAGULATION 12.1 Surface conditions during interaction Free energy of formation of a double layer Overlap of two flat double layers Interaction between dissimilar flat plates Interaction between two spherical particles Total potential energy of interaction Experimental studies of the equilibrium interaction between diffuse double layers Kinetics of coagulation Effect of polymers on colloid stability INTRODUCTION TO STATISTICAL MECHANICS OF FLUIDS 13.1 Introduction Molecular interactions The structure of liquids The potential of mean force 646

5 xii I CONTENTS 13.5 Time-dependent correlation functions Applications of the pair distribution function Measurement of correlation functions Calculation of distribution functions SCATTERING STUDIES OF COLLOID STRUCTURE 14.1 Introduction Relating potential to structure Use of scattering to measure structure Structure of concentrated isotropic dispersions of spherical particles Neutron reflectivity RHEOLOGY OF COLLOIDAL DISPERSIONS 15.1 Introduction Behaviour of time-independent inelastic fluids Behaviour of time-dependent inelastic fluids Visco-elastic fluids Measurement of rheological properties of inelastic fluids in Couette flow Capillary viscometer Cone and plate or cone and cone viscometer Time-dependent inelastic behaviour Microrheology Microscopic basis of rheological models 749 APPENDICES Appendix A1 Calculation of the allowed surface interaction modes in modern Dispersion Force Theory 767 Appendix A2 Evaluation of the sum of the roots of the dispersion relation 768 Appendix A3 Vector calculus and Poisson's equation 770 Appendix A4 Fourier transforms 777 Appendix A5 Elementary thermodynamic relationships in the absence of surface contributions 780 Appendix A6 Electrical units 784 INDEX 787