Introduction to Applied Colloid and Surface Chemistry

Georgios M. Kontogeorgis and Søren Kiil are both at the Technical University of Denmark, in the Dept of Chemical and Biochemical Engineering. Kontogeorgis is Professor of Applied Thermodynamics, and Kiil is Associate Professor in Coatings Science and Engineering.Prof Kontogeorgis has been teaching the colloid and surface chemistry course for 12 years, for the past 3 co-teaching with Kiil. Both authors have diverse research interests in strongly interconnected fields. Kontogeorgis' research interests are in the fields of thermodynamics, physical chemistry (especially surface science and polymers), while Kiil’s interests are primarily in coatings science and engineering (antifouling-, anticorrosive-, wind turbine blades etc).Both have valuable books publishing experience: Kontogeorgis most recently on thermodynamic models (2010, Wiley); and Kiil has co-authored a textbook on product design (2007, Wiley).

• Preface xiUseful Constants xviSymbols and Some Basic Abbreviations xviiAbout the Companion Web Site xx1 Introduction to Colloid and Surface Chemistry 11.1 What are the colloids and interfaces? Why are they important? Why do we study them together? 11.1.1 Colloids and interfaces 31.2 Applications 41.3 Three ways of classifying the colloids 51.4 How to prepare colloid systems 61.5 Key properties of colloids 71.6 Concluding remarks 7Appendix 1.1 8Problems 9References 102 Intermolecular and Interparticle Forces 112.1 Introduction – Why and which forces are of importance in colloid and surface chemistry? 112.2 Two important long-range forces between molecules 122.3 The van der Waals forces 152.3.1 Van der Waals forces between molecules 152.3.2 Forces between particles and surfaces 162.3.3 Importance of the van der Waals forces 212.4 Concluding remarks 25Appendix 2.1 A note on the uniqueness of the water molecule and some of the recent debates on water structure and peculiar properties 26References for the Appendix 2.1 28Problems 29References 333 Surface and Interfacial Tensions – Principles and Estimation Methods 343.1 Introduction 343.2 Concept of surface tension – applications 343.3 Interfacial tensions, work of adhesion and spreading 393.3.1 Interfacial tensions 393.3.2 Work of adhesion and cohesion 433.3.3 Spreading coefficient in liquid–liquid interfaces 443.4 Measurement and estimation methods for surface tensions 453.4.1 The parachor method 463.4.2 Other methods 483.5 Measurement and estimation methods for interfacial tensions 503.5.1 “Direct” theories (Girifalco–Good and Neumann) 513.5.2 Early “surface component” theories (Fowkes, Owens–Wendt, Hansen/Skaarup) 523.5.3 Acid–base theory of van Oss–Good (van Oss et al., 1987) – possibly the best theory to-date 573.5.4 Discussion 593.6 Summary 60Appendix 3.1 Hansen solubility parameters (HSP) for selected solvents 61Appendix 3.2 The “φ” parameter of the Girifalco–Good equation (Equation 3.16) for liquid–liquid interfaces. Data from Girifalco and Good (1957, 1960) 66Problems 67References 724 Fundamental Equations in Colloid and Surface Science 744.1 Introduction 744.2 The Young equation of contact angle 744.2.1 Contact angle, spreading pressure and work of adhesion for solid–liquid interfaces 744.2.2 Validity of the Young equation 774.2.3 Complexity of solid surfaces and effects on contact angle 784.3 Young–Laplace equation for the pressure difference across a curved surface 794.4 Kelvin equation for the vapour pressure, P, of a droplet (curved surface) over the “ordinary” vapour pressure Psat for a flat surface 804.4.1 Applications of the Kelvin equation 814.5 The Gibbs adsorption equation 824.6 Applications of the Gibbs equation (adsorption, monolayers, molecular weight of proteins) 834.7 Monolayers 864.8 Conclusions 89Appendix 4.1 Derivation of the Young–Laplace equation 90Appendix 4.2 Derivation of the Kelvin equation 91Appendix 4.3 Derivation of the Gibbs adsorption equation 91Problems 93References 955 Surfactants and Self-assembly. Detergents and Cleaning 965.1 Introduction to surfactants – basic properties, self-assembly and critical packing parameter (CPP) 965.2 Micelles and critical micelle concentration (CMC) 995.3 Micellization – theories and key parameters 1065.4 Surfactants and cleaning (detergency) 1125.5 Other applications of surfactants 1135.6 Concluding remarks 114Appendix 5.1 Useful relationships from geometry 115Appendix 5.2 The Hydrophilic–Lipophilic Balance (HLB) 116Problems 117References 1196 Wetting and Adhesion 1216.1 Introduction 1216.2 Wetting and adhesion via the Zisman plot and theories for interfacial tensions 1226.2.1 Zisman plot 1226.2.2 Combining theories of interfacial tensions with Young equation and work of adhesion for studying wetting and adhesion 1246.2.3 Applications of wetting and solid characterization 1306.3 Adhesion theories 1416.3.1 Introduction – adhesion theories 1416.3.2 Adhesive forces 1446.4 Practical adhesion: forces, work of adhesion, problems and protection 1476.4.1 Effect of surface phenomena and mechanical properties 1476.4.2 Practical adhesion – locus of failure 1486.4.3 Adhesion problems and some solutions 1496.5 Concluding remarks 154Problems 155References 1607 Adsorption in Colloid and Surface Science – A Universal Concept 1617.1 Introduction – universality of adsorption – overview 1617.2 Adsorption theories, two-dimensional equations of state and surface tension–concentration trends: a clear relationship 1617.3 Adsorption of gases on solids 1627.3.1 Adsorption using the Langmuir equation 1637.3.2 Adsorption of gases on solids using the BET equation 1647.4 Adsorption from solution 1687.4.1 Adsorption using the Langmuir equation 1687.4.2 Adsorption from solution – the effect of solvent and concentration on adsorption 1717.5 Adsorption of surfactants and polymers 1737.5.1 Adsorption of surfactants and the role of CPP 1737.5.2 Adsorption of polymers 1747.6 Concluding remarks 179Problems 180References 1848 Characterization Methods of Colloids – Part I: Kinetic Properties and Rheology 1858.1 Introduction – importance of kinetic properties 1858.2 Brownian motion 1858.3 Sedimentation and creaming (Stokes and Einstein equations) 1878.3.1 Stokes equation 1878.3.2 Effect of particle shape 1888.3.3 Einstein equation 1908.4 Kinetic properties via the ultracentrifuge 1918.4.1 Molecular weight estimated from kinetic experiments (1 = medium and 2 = particle or droplet) 1938.4.2 Sedimentation velocity experiments (1 = medium and 2 = particle or droplet) 1938.5 Osmosis and osmotic pressure 1938.6 Rheology of colloidal dispersions 1948.6.1 Introduction 1948.6.2 Special characteristics of colloid dispersions’ rheology 1968.7 Concluding remarks 198Problems 198References 2019 Characterization Methods of Colloids – Part II: Optical Properties (Scattering, Spectroscopy and Microscopy) 2029.1 Introduction 2029.2 Optical microscopy 2029.3 Electron microscopy 2049.4 Atomic force microscopy 2069.5 Light scattering 2079.6 Spectroscopy 2099.7 Concluding remarks 210Problems 210References 21010 Colloid Stability – Part I: The Major Players (van der Waals and Electrical Forces) 21110.1 Introduction – key forces and potential energy plots – overview 21110.1.1 Critical coagulation concentration 21310.2 van der Waals forces between particles and surfaces – basics 21410.3 Estimation of effective Hamaker constants 21510.4 vdW forces for different geometries – some examples 21710.4.1 Complex fluids 21910.5 Electrostatic forces: the electric double layer and the origin of surface charge 21910.6 Electrical forces: key parameters (Debye length and zeta potential) 22210.6.1 Surface or zeta potential and electrophoretic experiments 22310.6.2 The Debye length 22510.7 Electrical forces 22810.7.1 Effect of particle concentration in a dispersion 22910.8 Schulze–Hardy rule and the critical coagulation concentration (CCC) 23010.9 Concluding remarks on colloid stability, the vdW and electric forces 23310.9.1 vdW forces 23310.9.2 Electric forces 234Appendix 10.1 A note on the terminology of colloid stability 235Appendix 10.2 Gouy–Chapman theory of the diffuse electrical double-layer 236Problems 238References 24211 Colloid Stability – Part II: The DLVO Theory – Kinetics of Aggregation 24311.1 DLVO theory – a rapid overview 24311.2 DLVO theory – effect of various parameters 24411.3 DLVO theory – experimental verification and applications 24511.3.1 Critical coagulation concentration and the Hofmeister series 24511.3.2 DLVO, experiments and limitations 24711.4 Kinetics of aggregation 25511.4.1 General – the Smoluchowski model 25511.4.2 Fast (diffusion-controlled) coagulation 25511.4.3 Stability ratio W 25511.4.4 Structure of aggregates 25711.5 Concluding remarks 264Problems 265References 26812 Emulsions 26912.1 Introduction 26912.2 Applications and characterization of emulsions 26912.3 Destabilization of emulsions 27212.4 Emulsion stability 27312.5 Quantitative representation of the steric stabilization 27512.5.1 Temperature-dependency of steric stabilization 27612.5.2 Conditions for good stabilization 27712.6 Emulsion design 27812.7 PIT – Phase inversion temperature of emulsion based on non-ionic emulsifiers 27912.8 Concluding remarks 279Problems 280References 28213 Foams 28313.1 Introduction 28313.2 Applications of foams 28313.3 Characterization of foams 28513.4 Preparation of foams 28713.5 Measurements of foam stability 28713.6 Destabilization of foams 28813.6.1 Gas diffusion 28913.6.2 Film (lamella) rupture 29013.6.3 Drainage of foam by gravity 29113.7 Stabilization of foams 29313.7.1 Changing surface viscosity 29313.7.2 Surface elasticity 29313.7.3 Polymers and foam stabilization 29513.7.4 Additives 29613.7.5 Foams and DLVO theory 29613.8 How to avoid and destroy foams 29613.8.1 Mechanisms of antifoaming/defoaming 29713.9 Rheology of foams 29913.10 Concluding remarks 300Problems 301References 30214 Multicomponent Adsorption 30314.1 Introduction 30314.2 Langmuir theory for multicomponent adsorption 30414.3 Thermodynamic (ideal and real) adsorbed solution theories (IAST and RAST) 30614.4 Multicomponent potential theory of adsorption (MPTA) 31214.5 Discussion. Comparison of models 31514.5.1 IAST – literature studies 31514.5.2 IAST versus Langmuir 31514.5.3 MPTA versus IAST versus Langmuir 31714.6 Conclusions 317Acknowledgments 319Appendix 14.1 Proof of Equations 14.10a,b 319Problems 319References 32015 Sixty Years with Theories for Interfacial Tension – Quo Vadis? 32115.1 Introduction 32115.2 Early theories 32115.3 van Oss–Good and Neumann theories 33115.3.1 The two theories in brief 33115.3.2 What do van Oss–Good and Neumann say about their own theories? 33315.3.3 What do van Oss–Good and Neumann say about each other’s theories? 33415.3.4 What do others say about van Oss–Good and Neumann theories? 33515.3.5 What do we believe about the van Oss–Good and Neumann theories? 33815.4 A new theory for estimating interfacial tension using the partial solvation parameters (Panayiotou) 33915.5 Conclusions – Quo Vadis? 344Problems 345References 34916 Epilogue and Review Problems 352Review Problems in Colloid and Surface Chemistry 353Index 358