Tharwat F. Tadros – författare

This fundamental book on interfacial phenomena forms the basis of application of interface and colloid science to various disperse systems. These include suspensions, emulsions, nano-dispersions, wetting, spreading, deposition and adhesion of particles to surfaces. These systems occur in most industrial applications, such as personal care and cosmetic formulations, pharmaceutical systems particularly for controlled and targeted delivery of drugs, agrochemical formulations and enhancement of their biological performance, paints and coatings as well as most food formulations. These applications are described in volume 2. The text is very valuable for formulation chemists, chemical engineers and technologies who are involved in such applications. In addition this fundamental text is also valuable for research scientists and Ph.D. students investigating various aspects of interface and colloid science.

General introduction - Definition of nanodispersions (nanosuspensions, nanoemulsions, swollen micelles or microemulsions, liposomes and vesicles) and their size range. General description of their colloid stability. Main advantages of nanodispersions and their industrial applications.Preparation of nanosuspensions by top-up process - Nucleation and growth and control of particle size distribution. Factors determining the formation of narrow particle size distribution. Role of surfactants and polymers. Preparation of nano-polymer colloids (lattices) by emulsion and dispersion polymerization. Factors affects the stability of nanosuspensions.Preparation of nanosuspensions by bottom down process - Dispersion of preformed particles in liquids and the need of a wetting agent. Break-up of aggregates and agglomerates by application of high speed stirrers. Reduction of particle size by application of intense energy (microfluidization or bead milling). Maintenance of the colloid stability of the resulting particles. Reduction of Ostwald ripening.Industrial applications of nanosuspensions - Application in pharmacy to enhance bioavailability, Application in sunscreens for UV protection. Application in paints and coatings.Preparation of nanoemulsions by the use of high pressure homogenisers - Principles of emulsion formation and the role of the emulsifier. Selection of emulsifiers. Methods of emulsification and prevention of coalescence during emulsification. Origin of colloid stability of nanoemulsions. Prevention of Ostwald ripeningLow energy methods for nanoemulsion preparation - The phase inversion composition method and the role of mixing the surfactant with oil and water. The phase inversion temperature method for preparation of nanoemulsions. Preparation of nanoemulsions by dilution of microemulsions.Practical examples of nanoemulsions and their industrial application - Nanoemulsions based on non-ionic surfactants and the role of the hydrophilic-lipophilic balance. Effect of oil solubility on the stabilityof nanoemulsions. Nanoemulsions based on polymeric surfactants. Applications in pharmacy and cosmetics.Swollen micelles or microemulsionsDefinition of microemulsions and their size range. Thermodynamic definition of microemulstions. Theories of microemulsion formation and stability. Characterisation of microemulsions using scattering, conductivity and NMR rechniques.Formulation of microemulsions and their industrial applications - Distinction between microemulsions and macroemulsions. Formulation of oil/water and water/oil microemulsions. Selection of emulsifiers for microemulsions. Application of microemulsions in tertiary oil recovery.Liposomes and vesicles - Formation of multilamellar lipid layers (liposomes) by dispersion of lipids in water. Formation of unilamellar vesicles by sonication of the liposomes. Factors responsible for stabilisation of liposomes and vesicles. Use of block copolymers to enhance the stability of vesicles. Applications of liposomes and vesicles in pharmacy and cosmetics.

Surfactants are surface active agents, molecules that have a significant role in emulsions, suspensions, and foams. They find widespread application in personal care, cosmetics, pharmaceuticals, agrochemicals and the food industry. The main objective of this graduate level textbook is to present an overview of the classification, physical properties, phase behavior, their effects and applications of surfactants, e.g. as emulsifiers, foam stabilizer, in nano- and microemulsions and as wetting agents.

The main objective of this volume is to demonstrate the importance of the fundamental aspects of interfacial phenomena in various industrial applications. The text provides the reader with the knowledge that is essential for the composition of the complex multi-phase systems used in the above mentioned areas of application. It should enable the physical and formulation chemist as well as the chemical engineer in designing the formulation on the basis of a rational approach. It will also enable the formulation scientist to better understanding the factors responsible for producing a stable product with optimum application conditions. The book should also be very useful for teaching the subject of formulation at academic institutions.

Surfactants are surface active agents, molecules that have a significant role in emulsions, suspensions, and foams. They find widespread application in personal care, cosmetics, pharmaceuticals, agrochemicals and the food industry. The main objective of this graduate level textbook is to present an overview of the classification, physical properties, phase behavior, their effects and applications of surfactants, e.g. as emulsifiers, foam stabilizer, in nano- and microemulsions and as wetting agents.

The main objective of this volume is to demonstrate the importance of the fundamental aspects of interfacial phenomena in various industrial applications. The text provides the reader with the knowledge that is essential for the composition of the complex multi-phase systems used in the above mentioned areas of application. It should enable the physical and formulation chemist as well as the chemical engineer in designing the formulation on the basis of a rational approach. It will also enable the formulation scientist to better understanding the factors responsible for producing a stable product with optimum application conditions. The book should also be very useful for teaching the subject of formulation at academic institutions.

This fundamental book on interfacial phenomena forms the basis of application of interface and colloid science to various disperse systems. These include suspensions, emulsions, nano-dispersions, wetting, spreading, deposition and adhesion of particles to surfaces. These systems occur in most industrial applications, such as personal care and cosmetic formulations, pharmaceutical systems particularly for controlled and targeted delivery of drugs, agrochemical formulations and enhancement of their biological performance, paints and coatings as well as most food formulations. These applications are described in volume 2. The text is very valuable for formulation chemists, chemical engineers and technologies who are involved in such applications. In addition this fundamental text is also valuable for research scientists and Ph.D. students investigating various aspects of interface and colloid science.

General introduction - Definition of nanodispersions (nanosuspensions, nanoemulsions, swollen micelles or microemulsions, liposomes and vesicles) and their size range. General description of their colloid stability. Main advantages of nanodispersions and their industrial applications.Preparation of nanosuspensions by top-up process - Nucleation and growth and control of particle size distribution. Factors determining the formation of narrow particle size distribution. Role of surfactants and polymers. Preparation of nano-polymer colloids (lattices) by emulsion and dispersion polymerization. Factors affects the stability of nanosuspensions.Preparation of nanosuspensions by bottom down process - Dispersion of preformed particles in liquids and the need of a wetting agent. Break-up of aggregates and agglomerates by application of high speed stirrers. Reduction of particle size by application of intense energy (microfluidization or bead milling). Maintenance of the colloid stability of the resulting particles. Reduction of Ostwald ripening.Industrial applications of nanosuspensions - Application in pharmacy to enhance bioavailability, Application in sunscreens for UV protection. Application in paints and coatings.Preparation of nanoemulsions by the use of high pressure homogenisers - Principles of emulsion formation and the role of the emulsifier. Selection of emulsifiers. Methods of emulsification and prevention of coalescence during emulsification. Origin of colloid stability of nanoemulsions. Prevention of Ostwald ripeningLow energy methods for nanoemulsion preparation - The phase inversion composition method and the role of mixing the surfactant with oil and water. The phase inversion temperature method for preparation of nanoemulsions. Preparation of nanoemulsions by dilution of microemulsions.Practical examples of nanoemulsions and their industrial application - Nanoemulsions based on non-ionic surfactants and the role of the hydrophilic-lipophilic balance. Effect of oil solubility on the stabilityof nanoemulsions. Nanoemulsions based on polymeric surfactants. Applications in pharmacy and cosmetics.Swollen micelles or microemulsionsDefinition of microemulsions and their size range. Thermodynamic definition of microemulstions. Theories of microemulsion formation and stability. Characterisation of microemulsions using scattering, conductivity and NMR rechniques.Formulation of microemulsions and their industrial applications - Distinction between microemulsions and macroemulsions. Formulation of oil/water and water/oil microemulsions. Selection of emulsifiers for microemulsions. Application of microemulsions in tertiary oil recovery.Liposomes and vesicles - Formation of multilamellar lipid layers (liposomes) by dispersion of lipids in water. Formation of unilamellar vesicles by sonication of the liposomes. Factors responsible for stabilisation of liposomes and vesicles. Use of block copolymers to enhance the stability of vesicles. Applications of liposomes and vesicles in pharmacy and cosmetics.

Chapter 1 General IntroductionDefinition of emulsions and the role of the emulsifier. Classification based on the nature of the emulsifier. Classification based on the structure of the system. General instability problems with emulsions : creaming/sedimentation, flocculation, Ostwald ripening, coalescence and phase inversion. Importance of emulsions in various industrial applications.

Chapter 2 Thermodynamics of Emulsion Formation and BreakdownApplication of the second law of thermodynamics for emulsion formation : Balance of energy and entropy and non-spontaneous formation of emulsions. Breakdown of the emulsion by flocculation and coalescence in the absence of an emulsifier. Role of the emulsifier in preventing flocculation and coalescence by creating an energy barrier resulting from the repulsive energies between the droplets.

Chapter 3 Interaction Forces between Emulsion DropletsVan der Waals attraction and its dependence on droplet size, Hamaker constant and separation distance between the droplets. Electrostatic repulsion resulting from the presence of electrical double layers and its dependence on surface (or zeta) potential and electrolyte concentration and valency. Combination of the van der Waals attraction with double layer repulsion and the theory of colloid stability. Steric repulsion resulting from the presence of adsorbed non-ionic surfactants and polymers. Combination of van der Waals attraction with steric repulsion and the theory of steric stabilisation.

Chapter 4 Adsorption of Surfactants at the Oil/Water InterfaceThermodynamic analysis of surfactant adsorption and the Gibbs adsorption isotherm. Calculation of the amount of surfactant adsorption and area per surfactant molecule at the interface. Experimental techniques for measuring the interfacial tension.

Chapter 5 Mechanism of Emulsification and the Role of the EmulsifierDescription of the factors responsible for droplet deformation and its break-up. Role of surfactant in preventing coalescence during emulsification. Definition of the Gibbs dilational elasticity and the Marangoni effect in preventing coalescence.

Chapter 6 Methods of EmulsificationPipe flow, static mixers and high speed stirrers (rotor-stator mixer). Laminar and turbulent flow. Membrane emulsification. High pressure homogenisers and ultrasonic methods.

Chapter 7 Selection of EmulsifiersThe hydrophilic-lipophilic-balance (HLB) and its application in surfactant selection. Calculation of HLB numbers and the effect of the nature of the oil phase. The phase inversion temperature (PIT) method for emulsifier selection. The cohesive energy ratio method for emulsifier selection.

Chapter 8 Creaming/Sedimentation of Emulsions and its preventionDriving force for creaming/sedimentation: effect of gravity, droplet size and density difference between the oil and continuous phase. Calculation of the rate of creaming/sedimentation in dilute emulsions. Influence of increase of the volume fraction of the disperse phase on the rate of creaming/sedimentation. Reduction of creaming/sedimentation: Balance of the density of the two phases, reduction of droplet size and effect of addition of ''''thickeners''.

Chapter 9 Flocculation of Emulsions and its PreventionFactors affecting flocculation. Calculation of fast and slow flocculation rate. Definition of stability ratio and its dependence on electrolyte concentration and valency. Definition of the critical coagulation concentration and its dependence on electrolyte valency. Reduction of flocculation by enhancing the repulsive forces.

Chapter 10 Ostwald Ripening and its ReductionFactors responsible for Ostwald ripening : difference in solubility between small and large droplets and the Kelvin equation. Calculation of the rate of Ostwald ripening. Reduction of Ostwald ripening by incorporation of a small amount of highly insoluble oil. Reduction of Ostwald ripening by the use of strongly adsorbed polymeric surfactant and enhancement of the Gibbs elasticity.

Chapter 11 Emulsion Coalescence and its PreventionDriving force for emulsion coalescence : Thinning and disruption of the liquid film between the droplets. The concept of disjoining pressure for prevention of coalescence. Methods for reduction or elimination of coalescence : Use of mixed surfactant films, use of lamellar liquid crystalline phases and use of polymeric surfactants.

Chapter 12 Phase Inversion and its PreventionDistinction between catastrophic and transient phase inversion. Influence of the disperse volume fraction and surfactant HLB number. Explanation of the factors responsible for phase inversion.

Chapter 13 Characterisation of EmulsionsMeasurement of droplet size distribution : Optical microscopy and image analysis. Phase contrast and polarising microscopyDiffraction methods. Confocal laser microscopy. Back scattering methods

Chapter 14 Industrial Application of Emulsions14.1 Application in Pharmacy14.2 Application in Cosmetics 14.3 Application in Agrochemicals14.4 Application in Paints14.5 Application in the Oil Industry

Chapter 1 General IntroductionDefinition of emulsions and the role of the emulsifier. Classification based on the nature of the emulsifier. Classification based on the structure of the system. General instability problems with emulsions : creaming/sedimentation, flocculation, Ostwald ripening, coalescence and phase inversion. Importance of emulsions in various industrial applications.

Chapter 2 Thermodynamics of Emulsion Formation and BreakdownApplication of the second law of thermodynamics for emulsion formation : Balance of energy and entropy and non-spontaneous formation of emulsions. Breakdown of the emulsion by flocculation and coalescence in the absence of an emulsifier. Role of the emulsifier in preventing flocculation and coalescence by creating an energy barrier resulting from the repulsive energies between the droplets.

Chapter 3 Interaction Forces between Emulsion DropletsVan der Waals attraction and its dependence on droplet size, Hamaker constant and separation distance between the droplets. Electrostatic repulsion resulting from the presence of electrical double layers and its dependence on surface (or zeta) potential and electrolyte concentration and valency. Combination of the van der Waals attraction with double layer repulsion and the theory of colloid stability. Steric repulsion resulting from the presence of adsorbed non-ionic surfactants and polymers. Combination of van der Waals attraction with steric repulsion and the theory of steric stabilisation.

Chapter 4 Adsorption of Surfactants at the Oil/Water InterfaceThermodynamic analysis of surfactant adsorption and the Gibbs adsorption isotherm. Calculation of the amount of surfactant adsorption and area per surfactant molecule at the interface. Experimental techniques for measuring the interfacial tension.

Chapter 5 Mechanism of Emulsification and the Role of the EmulsifierDescription of the factors responsible for droplet deformation and its break-up. Role of surfactant in preventing coalescence during emulsification. Definition of the Gibbs dilational elasticity and the Marangoni effect in preventing coalescence.

Chapter 6 Methods of EmulsificationPipe flow, static mixers and high speed stirrers (rotor-stator mixer). Laminar and turbulent flow. Membrane emulsification. High pressure homogenisers and ultrasonic methods.

Chapter 7 Selection of EmulsifiersThe hydrophilic-lipophilic-balance (HLB) and its application in surfactant selection. Calculation of HLB numbers and the effect of the nature of the oil phase. The phase inversion temperature (PIT) method for emulsifier selection. The cohesive energy ratio method for emulsifier selection.

Chapter 8 Creaming/Sedimentation of Emulsions and its preventionDriving force for creaming/sedimentation: effect of gravity, droplet size and density difference between the oil and continuous phase. Calculation of the rate of creaming/sedimentation in dilute emulsions. Influence of increase of the volume fraction of the disperse phase on the rate of creaming/sedimentation. Reduction of creaming/sedimentation: Balance of the density of the two phases, reduction of droplet size and effect of addition of ''''thickeners''.

Chapter 9 Flocculation of Emulsions and its PreventionFactors affecting flocculation. Calculation of fast and slow flocculation rate. Definition of stability ratio and its dependence on electrolyte concentration and valency. Definition of the critical coagulation concentration and its dependence on electrolyte valency. Reduction of flocculation by enhancing the repulsive forces.

Chapter 10 Ostwald Ripening and its ReductionFactors responsible for Ostwald ripening : difference in solubility between small and large droplets and the Kelvin equation. Calculation of the rate of Ostwald ripening. Reduction of Ostwald ripening by incorporation of a small amount of highly insoluble oil. Reduction of Ostwald ripening by the use of strongly adsorbed polymeric surfactant and enhancement of the Gibbs elasticity.

Chapter 11 Emulsion Coalescence and its PreventionDriving force for emulsion coalescence : Thinning and disruption of the liquid film between the droplets. The concept of disjoining pressure for prevention of coalescence. Methods for reduction or elimination of coalescence : Use of mixed surfactant films, use of lamellar liquid crystalline phases and use of polymeric surfactants.

Chapter 12 Phase Inversion and its PreventionDistinction between catastrophic and transient phase inversion. Influence of the disperse volume fraction and surfactant HLB number. Explanation of the factors responsible for phase inversion.

Chapter 13 Characterisation of EmulsionsMeasurement of droplet size distribution : Optical microscopy and image analysis. Phase contrast and polarising microscopyDiffraction methods. Confocal laser microscopy. Back scattering methods

Chapter 14 Industrial Application of Emulsions14.1 Application in Pharmacy14.2 Application in Cosmetics 14.3 Application in Agrochemicals14.4 Application in Paints14.5 Application in the Oil Industry

Formulations starts with a general introduction, explaining interaction forces between particles and droplets, self-assembly systems, polymeric surfactants and nanoemulsions. The second part covers the industrial examples ranging from foams, soaps over to hair care, sunscreen and make-up products. Combines information needed by formulation chemists as well as researchers in the cosmetic industry due the increasing number of products.

Formulations starts with a general introduction, explaining interaction forces between particles and droplets, self-assembly systems, polymeric surfactants and nanoemulsions. The second part covers the industrial examples ranging from foams, soaps over to hair care, sunscreen and make-up products. Combines information needed by formulation chemists as well as researchers in the cosmetic industry due the increasing number of products.

Suspension Concentrates is a survey into the theory of the formulation and stabilization of suspensions, elaborating on the breaking of aggregates and agglomerates and the role of dispersing agents on flocculation and electrostatic and steric stabilization. Practical analysis by rheology is discussed. Suspension Concentrates is ideal for research scientists and Ph.D. students investigating chemistry, chemical engineering and colloidal science.

Suspension Concentrates is a survey into the theory of the formulation and stabilization of suspensions, elaborating on the breaking of aggregates and agglomerates and the role of dispersing agents on flocculation and electrostatic and steric stabilization. Practical analysis by rheology is discussed. Suspension Concentrates is ideal for research scientists and Ph.D. students investigating chemistry, chemical engineering and colloidal science.

Polymeric Surfactants covers the structure and stability origins of these highly useful surfactants. Adsorption and solution properties in emulsions are discussed based on their underlying thermodynamics and kinetics. Research scientists and Ph.D. students investigating chemistry, chemical engineering and colloidal science will benefit from this text on polymeric surfactants and their value in preparation and stabilization of disperse systems.

Polymeric Surfactants covers the structure and stability origins of these highly useful surfactants. Adsorption and solution properties in emulsions are discussed based on their underlying thermodynamics and kinetics. Research scientists and Ph.D. students investigating chemistry, chemical engineering and colloidal science will benefit from this text on polymeric surfactants and their value in preparation and stabilization of disperse systems.