Applied Surfactants

After finishing his PhD at Alexandria University, Tharwat Tadros was appointed lecturer in Physical Chemistry (1962-1966) at the same University. Between 1966 and 1969, he spent a sabbatical at the Agricultural University of Wageningen and T.N.O in Delft, the Netherlands. Thereafter he joined I.C.I. and ZENECA until 1994, where he researched various fields of surfactants, emulsions, suspensions, microemulsions, wetting spreading and adhesion and rheology. During that period he was also appointed visiting professor at Imperial College London, Bristol University and Reading University. In 1992, he was elected President of the International Association of Colloid and Interface Science. Since leaving ZENECA, Dr Tadros has worked as a consultant for various industries and also given several courses in his specialized field. He is the recipient of two medals from the Royal Society of Chemistry in the UK, and has more than 250 scientific papers to his name.

• Preface xix1 Introduction 11.1 General Classification of Surface Active Agents 21.2 Anionic Surfactants 21.2.1 Carboxylates 31.2.2 Sulphates 41.2.3 Sulphonates 41.2.4 Phosphate-containing Anionic Surfactants 51.3 Cationic Surfactants 61.4 Amphoteric (Zwitterionic) Surfactants 71.5 Nonionic Surfactants 81.6 Speciality Surfactants – Fluorocarbon and Silicone Surfactants 131.7 Polymeric Surfactants 141.8 Toxicological and Environmental Aspects of Surfactants 15References 162 Physical Chemistry of Surfactant Solutions 192.1 Properties of Solutions of Surface Active Agents 192.2 Solubility–Temperature Relationship for Surfactants 252.3 Thermodynamics of Micellization 262.4 Micellization in Surfactant Mixtures (Mixed Micelles) 342.5 Surfactant–Polymer Interaction 39References 503 Phase Behavior of Surfactant Systems 533.1 Solubility–Temperature Relationship for Ionic Surfactants 573.2 Surfactant Self-Assembly 583.3 Structure of Liquid Crystalline Phases 593.4 Experimental Studies of the Phase Behaviour of Surfactants 623.5 Phase Diagrams of Ionic Surfactants 653.6 Phase Diagrams of Nonionic Surfactants 66References 714 Adsorption of Surfactants at the Air/Liquid and Liquid/Liquid Interfaces 734.1 Introduction 734.2 Adsorption of Surfactants 744.3 Interfacial Tension Measurements 80References 845 Adsorption of Surfactants and Polymeric Surfactants at the Solid/Liquid Interface 855.1 Introduction 855.2 Surfactant Adsorption 865.3 Adsorption of Polymeric Surfactants at the Solid/Liquid Interface 935.4 Adsorption and Conformation of Polymeric Surfactants at Interfaces 965.5 Experimental Methods for Measurement of Adsorption Parameters for Polymeric Surfactants 102References 1126 Applications of Surfactants in Emulsion Formation and Stabilisation 1156.1 Introduction 1156.2 Physical Chemistry of Emulsion Systems 1176.3 Mechanism of Emulsification 1236.4 Methods of Emulsification 1266.5 Role of Surfactants in Emulsion Formation 1276.6 Selection of Emulsifiers 1346.7 Cohesive Energy Ratio (CER) Concept for Emulsifier Selection 1406.8 Critical Packing Parameter (CPP) for Emulsifier Selection 1426.9 Creaming or Sedimentation of Emulsions 1436.10 Flocculation of Emulsions 1506.11 Ostwald Ripening 1546.12 Emulsion Coalescence 1556.13 Phase Inversion 1586.14 Rheology of Emulsions 1596.15 Interfacial Rheology 1626.16 Investigations of Bulk Rheology of Emulsion Systems 1716.17 Experimental Methods for Assessing Emulsion Stability 182References 1847 Surfactants as Dispersants and Stabilisation of Suspensions 1877.1 Introduction 1877.2 Role of Surfactants in Preparation of Solid/Liquid Dispersions 1887.3 Effect of Surfactant Adsorption 1997.4 Wetting of Powders by Liquids 2017.5 Rate of Penetration of Liquids 2037.6 Structure of the Solid/Liquid Interface 2047.7 Structure of the Electrical Double Layer 2067.8 Electrical Double Layer Repulsion 2077.9 Van der Waals Attraction 2087.10 Total Energy of Interaction: Deryaguin–Landau–Verwey–Overbeek (DLVO) Theory 2107.11 Criteria for Stabilisation of Dispersions with Double Layer Interaction 2117.12 Electrokinetic Phenomena and the Zeta Potential 2127.13 Calculation of Zeta Potential 2147.14 Measurement of Electrophoretic Mobility 2167.15 General Classification of Dispersing Agents 2177.16 Steric Stabilisation of Suspensions 2187.17 Interaction Between Particles Containing Adsorbed Polymer Layers 2197.18 Criteria for Effective Steric Stabilisation 2247.19 Flocculation of Sterically Stabilised Dispersions 2247.20 Properties of Concentrated Suspensions 2257.21 Characterisation of Suspensions and Assessment of their Stability 2317.22 Bulk Properties of Suspensions 2357.23 Sedimentation of Suspensions and Prevention of Formation of Dilatant Sediments (Clays) 2497.24 Prevention of Sedimentation and Formation of Dilatant Sediments 253References 2568 Surfactants in Foams 2598.1 Introduction 2598.2 Foam Preparation 2608.3 Foam Structure 2618.4 Classification of Foam Stability 2628.5 Drainage and Thinning of Foam Films 2638.6 Theories of Foam Stability 2678.7 Foam Inhibitors 2748.8 Physical Properties of Foams 2788.9 Experimental Techniques for Studying Foams 281References 2839 Surfactants in Nano-Emulsions 2859.1 Introduction 2859.2 Mechanism of Emulsification 2879.3 Methods of Emulsification and the Role of Surfactants 2899.4 Preparation of Nano-Emulsions 2909.5 Steric Stabilization and the Role of the Adsorbed Layer Thickness 2949.6 Ostwald Ripening 2969.7 Practical Examples of Nano-Emulsions 298References 30710 Microemulsions 30910.1 Introduction 30910.2 Thermodynamic Definition of Microemulsions 31010.3 Mixed Film and Solubilisation Theories of Microemulsions 31210.4 Thermodynamic Theory of Microemulsion Formation 31610.5 Free Energy of Formation of Microemulsion 31810.6 Factors Determining W/O versus O/W Microemulsions 32010.7 Characterisation of Microemulsions Using Scattering Techniques 321References 33311 Role of Surfactants in Wetting, Spreading and Adhesion 33511.1 General Introduction 33511.2 Concept of Contact Angle 33811.3 Adhesion Tension 34011.4 Work of Adhesion W a 34211.5 Work of Cohesion 34211.6 Calculation of Surface Tension and Contact Angle 34311.7 Spreading of Liquids on Surfaces 34611.8 Contact Angle Hysteresis 34611.9 Critical Surface Tension of Wetting and the Role of Surfactants 34911.10 Effect of Surfactant Adsorption 35111.11 Measurement of Contact Angles 35211.12 Dynamic Processes of Adsorption and Wetting 35611.13 Wetting Kinetics 36411.14 Adhesion 36811.15 Deposition of Particles on Surfaces 37911.16 Particle–Surface Adhesion 38911.17 Role of Particle Deposition and Adhesion in Detergency 393References 39612 Surfactants in Personal Care and Cosmetics 39912.1 Introduction 39912.2 Surfactants Used in Cosmetic Formulations 40212.3 Cosmetic Emulsions 40312.4 Nano-Emulsions in Cosmetics 41212.5 Microemulsions in Cosmetics 41312.6 Liposomes (Vesicles) 41312.7 Multiple Emulsions 41612.8 Polymeric Surfactants and Polymers in Personal Care and Cosmetic Formulations 41812.9 Industrial Examples of Personal Care Formulations and the Role of Surfactants 419References 43213 Surfactants in Pharmaceutical Formulations 43313.1 General Introduction 43313.2 Surfactants in Disperse Systems 43713.3 Electrostatic Stabilisation of Disperse Systems 44413.4 Steric Stabilization of Disperse Systems 44713.5 Surface Activity and Colloidal Properties of Drugs 45213.6 Biological Implications of the Presence of Surfactants in Pharmaceutical Formulations 46013.7 Aspects of Surfactant Toxicity 46213.8 Solubilised Systems 46413.9 Pharmaceutical Suspensions 47113.10 Pharmaceutical Emulsions 47713.11 Multiple Emulsions in Pharmacy 48213.12 Liposomes and Vesicles in Pharmacy 48713.13 Nano-particles, Drug Delivery and Drug Targeting 49113.14 Topical Formulations and Semi-solid Systems 494References 49914 Applications of Surfactants in Agrochemicals 50314.1 Introduction 50314.2 Emulsifiable Concentrates 50614.3 Concentrated Emulsions in Agrochemicals (EWs) 52414.4 Suspension Concentrates (SCs) 53714.5 Microemulsions in Agrochemicals 55814.6 Role of Surfactants in Biological Enhancement 567References 59215 Surfactants in the Food Industry 59515.1 Introduction 59515.2 Interaction Between Food-grade Surfactants and Water 59615.3 Proteins as Emulsifiers 60115.4 Protein–Polysaccharide Interactions in Food Colloids 60415.5 Polysaccharide–Surfactant Interactions 60615.6 Surfactant Association Structures, Microemulsions and Emulsions in Food 60815.7 Effect of Food Surfactants on the Rheology of Food Emulsions 60915.8 Practical Applications of Food Colloids 626References 629Subject Index 631

"This book provides a rich...source of information, especially for the industrial chemist who wishes to learn more about this fascinating world. ...this work will be consulted frequently by the practicing industrial surfactant chemist."Angewandte Chemie "This handbook meets the need for a comprehensive survey of surfactants and their properties, with a strong emphasis on applications and their correlation to the fundamentals. The author covers their classification, physical properties, phase behavior, adsorption, but also effects, such as wetting, spreading and adhesion, as well as industrial applications in personal care and cosmetics, pharmaceuticals, agrochemicals and food products. The author is a well-known expert on the topic of surfactants, with much experience in colloid science. In this volume, he uses his industrial experience to close the gap between the already published fundamentals of surfactants and their application in practice. Therefore, this book is recommended as a useful guideline for all scientists working in academics or industry with surface-active substances, especially in research and development. Together with 'Emulsions, Foams and Suspensions written by Laurier L. Schramm' and also published by Wiley-VCH this year, it is a basical platform for very special investigations in the interesting field of surfactants, such as sustainable enrichment of valuable plant ingredients by foaming for their further use as drugs or food additives."AFS: Advances in Food Sciences