Modern Aspects of Emulsion Science

Transcription

1 Modern Aspects of Emulsion Science Edited by Bernard P. Binks Department of Chemistry, University ofhull, UK THE ROYAL SOCIETY OF CHEMISTRY Information Services

2 Chapter 1 Emulsions - Recent Advances in Understanding Bernard P Binks Introduction Emulsion Type and the System Hydrophile-Lipophile Balance Emulsions of Two Liquid Phases Emulsions of Three Liquid Phases Phase Inversion Emulsion Stability Creaming Flocculation Coalescence Ostwald Ripening Gel Emulsions Forces between Oil-Water Interfaces Forces between Emulsion Drops Forces between a Drop and a Planar Oil-Water Interface References Chapter 2 Emulsion Formation 56 Pieter Walstra and Pauline E.A. Smulders 2.1 Introduction Regimes Droplet Break-up Laminar Flow Turbulent Flow Effect of Droplet Viscosity Effects of Scale and Continuous Phase Viscosity Roles of the Surfactant Surfactant Properties Effective Interfacial Tension Effect on Droplet Deformation Preventing Recoalescence 'Spontaneous Emulsification' 91

3 Vlll 2.5 Further Considerations Effects of Volume Fraction Emulsification Efficiency Membrane Emulsification Concluding Remarks References 98 Chapter 3 Emulsion Formation by Nucleation and Growth Mechanisms 100 Brian Vincent, Zoltan Kiraly and Tim M. Obey 3.1 Introduction Physical Methods Chemical Methods References 114 Chapter 4 Emulsion Flocculation and Creaming 115 Margaret M. Robins and David J. Hibberd 4.1 Introduction Instability Processes Strategies for Stability Interaction Potential between Droplets Flocculation Due to Polymers Emulsion Creaming Introduction and Theoretical Principles Ultrasonic Monitoring of Creaming Creamingof Polydisperse Emulsions without Added Polymer Creaming of Emulsions with Low Concentrations of Non-adsorbing polymer Creaming of Emulsions with High Concentrations of Non-adsorbing Polymer Creamingof Emulsions with Adsorbing Polymer Non-intrusive Determination of Flocculation in Emulsions Introduction and the Principle of Ultrasonic Scattering Ultrasonic Scattering from Unflocculated Emulsions Ultrasonic Scattering from Emulsions during Depletion Flocculation Summary References 143 Chapter 5 Rheology of Emulsions - The Relationship to Structure and Stability 145 Eric Dickinson 5.1 Introduction Theoretical Background Dilute Dispersions of Spherical Particles 147

4 5.2.2 Concentrated Dispersions of Spherical Particles Flocculated Emulsions Experimental Investigations Non-flocculated Emulsions Flocculated Emulsions References 171 Chapter 6 Phase Inversion and Drop Formation in Agitated Liquid-Liquid Dispersions in the Presence of Nonionic Surfactants 175 Brian W. Brooks, Howard N. Richmond and Mohamed Zerfa 6.1 Introduction Basic Principles of Phase Inversion Dissolution State of Nonionic Surfactants Change of Phase Behaviour with Temperature Factors Affecting Phase Inversion Dynamic Inversion Maps Catastrophic Inversion Transitional Inversion Partitioning of Surfactant Basis of Phase Separation Model Theory Applied to Transitional Inversion Lumping of Distributed Surfactant Terms Concluding Remarks References 202 Chapter 7 Coalescence in Emulsions 205 Alexey S. Kabalnov 7.1 Introduction Thermodynamic Properties of Surfactant Monolayers: Phase Behavior, Monolayer Elasticity and Interfacial Tension Surfactant Adsorption and Micellization Elasticity of Monolayers Spontaneous Curvature Implications for the Phase Behavior Interfacial Tension Experimental Trends in Macroemulsion Stability Surfactant Nature: Oriented Wedge Trend Bancroft's Rule HLB Scale 'Molecular Complexes' PIT Concept 'Optimal Surfactant Formulation' Other Empirical Correlations Multiple Emulsions 229 ix

5 X Surfactant Concentration: Tight Monolayer Packing Concentration for Formation of Black Films, C black Stabilization by a Lamellar Phase Effectof Volume Fractionof Disperse Phase and Droplet Size Theoryof Emulsion Coalescence Rupture of Single Films and the Emulsion Lifetime Activation Energy: de Vries Theory The Kabalnov-Wennerström Theory Nucleation Pore in Multilamellar-covered Emulsion Films The Kabalnov-Wennerström Theory versus Experiment Experimental Measurements of the Activation Energy and the Pre-exponent C 12 E 5 -n-octane-water-nacl System: Overall Trend Winsor III Region Winsor II Region Pre-exponent Surfactant Concentration Summary and Outlook References 257 Chapter 8 Lifetime and Destruction of Concentrated Emulsions Undergoing Coalescence 261 Benedicte Deminiere, Annie Colin, Fernando Leal Calderon and Jeröme Bibette 8.1 Introduction Thin Film Metastability: Background Destruction of Concentrated Emulsions Undergoing Coalescence Droplet Growth in Dense Emulsions Undergoing Coalescence Growth Model for Dense Emulsions Determination of a^r), co 0 and a Discussion Conclusion References 290 Chapter 9 Molecular Diffusion in Emulsions and Emulsion Mixtures 292 Jeffry G. Weers 9.1 Ostwald Ripening The Kelvin Equation Lifshitz-Slezov-Wagner (LSW) Theory Deviations from LSW Theory Effect ofbrownian Motion Effect of Disperse Phase Volume Fraction Role of Micelles in Facilitating Molecular Diffusion Stabilization ofemulsions withrespectto Ostwald Ripening 303

6 9.3.1 Ostwald Ripening in Emulsions Containing Two Disperse Phase Components Effect of the Interfacial Layer in Slowing Ostwald Ripening Other Ways of Slowing Ostwald Ripening Effect of Ostwald Ripening on Initial DropletSize Composition Ripening Praetical Importanceof Molecular Diffusion Ostwald Ripening in Fluorocarbon Emulsions Ostwald Ripening in Triglyceride Emulsions with Added Ethanol Miniemulsion Polymerization Use of Composition Ripening to Produce Large Monodisperse Latex Particles Stabilization of Gas Emulsions References 325 XI Chapter 10 Interactions and Macroscopic Properties of Emulsions and M icroemulsions 328 Dimiter N. Petsev 10.1 Introduction Pair Energy of Interaction van der Waals Interaction Energy Interactions Calculated by Means of Derjuagin's Approximation Interaction Energy Contributions Due to the Interfacial Properties of the Individual Droplet-Surface Area Extension and Bending Energies Applications of the Expressions for the Pair Interaction Energy Accuracy of the Model Shape-Actual Geometry of Two Interacting Deformable Droplets Dense Systems Nonionic Emulsions and Microemulsions Ionic Emulsions and Microemulsions Concluding Remarks References 363 Chapter 11 Gel Emulsions - Relationship between Phase Behaviour and Formation 367 Conxita Solans, Ramon Pons andhironobu Kunieda 11.1 Introduction Gel Emulsions: Stractural Aspects and Properties Structure Stability 370

7 xii Rheological Properties Diffusion Gel Emulsion Formation Phase Behaviour of Water/Polyoxyethylene Nonionic Surfactant/Oil Systems Methods of Preparation Relationship between Phase Behaviour and Spontaneous Gel Emulsion Formation Water-in-oil (W/O) Gel Emulsions Oil-in-water (O/W) Gel Emulsions References 393 Chapter 12 Applications of Emulsions 395 Thomas Förster and Wolfgang von Rybinski 12.1 Introduction Cosmetics Spreading Properties and Viscosity NewTypes of Emulsions Microemulsions Skin Penetration Metal Processing Rolling Oil Emulsions Lubricant Emulsions Textiles Textile Fiber Preparations Textile Finishing Oilfields Washing and Cleaning Processes Detergency Mechanisms Dry Cleaning Microemulsion Cleaners Soil Remediation References 423 Subject Index 427