Trends in Colloid and Interface Science X

The remarkable stability of water–in–crude oil emulsions is due to the presence of a complex adsorbed layer at the surfaces of the dispersed droplets. Except for its role as a steric barrier, little is known about the in situ properties of this interfacial structure. In this study, new insights into the adsorbed layer are provided by direct micrometre–scale measurements. At low crude content in the bulk where, according to interfacial tension isotherms, there should be little or no surfactants on the droplet surface, the adsorbed layer displays pronounced rigidity and is capable of preventing coalescence and coagulation of the droplets. Such interfaces are highly dissipative and can be well described by the Boussinesq–Scriven model. As the supply of surface active materials in the bulk (i.e. the crude content) increases, the adsorbed layer transforms from a rigid structure to a fluid interface. This fluid layer continues to inhibit coalescence, although signs of weak interdroplet adhesion begin to appear. Under area compression, the fluid interface will discharge micrometre–sized emulsion droplets into the oil phase via a 'budding' mechanism.

The Surface Evolver is an interactive program for studying the shapes of liquid surfaces. Recently added features permit the calculation of the Hessian matrix of second derivatives of the energy. The Hessian can be used for fast convergence to an equilibrium, and eigenvalue analysis of the stability of that equilibrium. This paper describes the use of the Hessian by the Surface Evolver, presents some sample stability analyses, and gives some numerical results on the accuracy and convergence of the methods. It is also shown how one can evolve unstable surfaces.

On the analysis of ionic surface conduction to unravel charging processes at macroscopic soft and hard solid–liquid interfaces

Professor Brian Vincent is a leading light in colloid science both in the UK and internationally. The science Brian has been involved in has influenced many areas of colloids both academically and industrially. He has collaborated with many sectors of industry (including pharmaceuticals, petrochemicals, agrochemicals, personal products, laundry products, paints and coatings). Brian has also been an active member of both the RSC and the SCI and has collaborated with many universities in the UK and overseas. Brian Vincent retired from the position of Leverhulme Professor of Physical Chemistry at the University of Bristol at the end of 2007 after a long and distinguished career which started as a chemistry undergraduate in Bristol in 1961. After obtaining a 1st class honours degree in Chemistry and an MSc in Surface Chemistry and Colloids and a PhD, Brian then moved to Wageningen to work in Hans Lyklema's laboratory on a Royal Society Fellowship. This was to be the start of a lifelong friendship and scientific collaboration with the Colloid and Physical Chemistry Group there. After returning to the UK in 1969, Brian had a succession of top posts and appointments culminating in 1993 when he became the 5th Leverhulme Professor in Physical Chemistry. In 1994, together with Dr Jim Goodwin, Brian founded the very successful Bristol Colloid Centre, an organisation which carries out short-term research and consultancy work for industry. Brian has received many honours including the SCI Founder's Lecture and Award, the SCI Distinguished Service Award, the RSC award in Surface and Colloid Chemistry and the Rehbinder Lecture and Medal (Moscow). He has had numerous invitations to give lectures throughout the world and has published over 250 papers, articles, books and patents during his career. He has also been very active at the academic /industry interface and has been a consultant for many of the leading companies that use colloid technology worldwide. This unique book is effectively a compendium of Brian's research, complemented by contributions on current topics in colloids by some of the leading scientists in the field. It provides an overview of the broad spectrum of colloid and interface science in which Brian has been a research pioneer for many years. The contributors to this symposium volume comprise a selection of Brian's past students and postdocs who have themselves pursued academic careers and other colleagues with whom he has worked extensively, all of whom are of international standing in colloid science and as such make this book an invaluable reference tool. The book backs up a meeting organised jointly by the RSC Colloid and Interface Science Group and the SCI Colloid & Surface Science Group and covers topics such as: The Adsorption of Small, Negative Particles onto Large Positive Particles Polymer Chemistry, Hypervelocity Physics and the CASSINI Space Mission The BV Droplets Downunder: From Model Emulsions to Drug Delivery Polymers and Surfactants at Interfaces Controlled Release as Desorption from Porous Polymeric Systems Characterisation and Application of Colloidal Micorogels Surface Modification The range of the subject material highlights Brian's own very broad interests in colloid science; it also reflects his long-standing interest in both the academic fundamentals as well as practical applications of the subject. The volume is dedicated to Brian in recognition of his considerable contribution to the world of colloid science and to the guidance and inspiration he has given to many future generations of colloid scientists. However, the book is not just reflective, but provides insight into new areas in which colloid science is being applied. It has specific appeal to both colloid scientists in academia and industry who will find this book fascinating as well as an indispensable reference tool.

The issue is dedicated to Professor Dr. h. c. Milan Schwuger on the occasion of his 60th birthday. Most of the papers included in this volume are related to the central theme: the interaction of surfa

Ultrasound for Characterizing Colloids - Particle Sizing, Zeta Potential, Rheology

Impact of atomic force microscopy on interface and colloid science

Spontaneous vesicle formation by mixed surfactants.- Electrolyte dependent phase separation in aqueous mixtures of a polyelectrolyte and an ionic surfactant.- Sodium dodecylsulfate-poly(ethyleneoxide) Interactions studied by time-resolved fluorescence quenching.- Spontaneous vesicle formation from a one-component solution of a biological surfactant.- Shear-induced transitions in micellar solutions.- Mixed short-chain lecithin/long-chain lecithin aggregates studied by small-angle neutron scattering.- Polymer-like giant micelles. An invesetigation by light scattering.- Scattering studies on colloids of biological interest (Amphiphilic systems).- Electron spin echo modulation and electron spin resonance studies of sodium dodecylsulfate and dodecyltrimethylammonium bromide micellar solutions: Effect of urea addition.- Aqueous solution properties of hydrophobically associating copolymers.- On mixed surfactant systems.- A shear-induced structure transition on a micellar solution measured by time-dependent small-angle neutron scattering.- A fluorescence and phosphorescence study of AOT/H2O/alkane systems in the L2 reversed micellar phase.- Interactions between surfactants and polymers. I: HPMC.- Interactions between surfactants and polymers. II: Polyelectrolytes.- Solubilization of aprotic additives in aqueous micelles.- Aggregation of polyamphiphiles with the polar head on the main chain.- Properties of water solubilized in reversed AOT micelles from near-infrared spectra.- Shape and solvation of water-containing reversed AOT micelles from viscosity measurements.- Mixed systems of fluorinated and hydrogenated nonionic surfactants: The air/water adsorbed film and micelles.- Stretched exponential relaxation processes in viscoelastic surfactant solutions.- 3PHEX: A new surfactant purification technique.- Solubilization of electrolyte solutiions in AOT reversed micelles. Conductivity percolation and phase behavior.- Peculiar micellar solubilization of benzyl alcohol in binary benzyldimethyletradecylammonium chloride and trimethyletradecylammonium chloride solutions: A calorimetric investigation.- Spin-controlled reactions on the micellar surface.- Glass transition in microemulsions.- W/O microemulsions as model systems for the study of water confined in microenvironments: Low resolution 1H magnetic resonance relaxation analysis.- Characterization of microemulsion-based organo-gels.- Pusle electron spin resonance and quasi-elastic light scattering of Winsor microemuslions.- A dynamic transition at the percolation threshold of a three-component microemulsion.- Phase electric birefringence measurements in attractive-type W/O microemulsion systems.- Fractal models for luminescence probing of organized assemblies. Studies with respect to the nature of the assembly, the temperature, and the quencher concentration.- Microemulsion as model system for the study of the glass-like transition: Refractive index and calorimetric measurements.- Hypersound velocity measurements in dense microemulsions, evidence of a viscoelastic behavior connected with the percolation process.- Critical phenomena in associative binary liquid mixtures with miscibility gap.- Surface-induced polarization properties of highly viscous liquids.- Aggregation phenomena in water-alcohol solutions. Thermodynamic and dynamic studies.- Effects of subphase pH on the successive deposition of monolayers of docosanoic acid onto mica.- Effect of surface charges on the electroporation process in lipid bilayers.- Optical study of monolayers at liquid interfaces: Direct observation of first order phase transitions and measurement of the bending elastic constant.- The interaction between polymer and surfactant as revealed by interfacial tension.- Adsorption of surfactants on low-charged layer silicates Part I: Adsorption of cationic surfactants.- Study of local and cooperative molecular movements in Poly(ethylene oxide) - Potassium thiocyanate complexes by mechanical measurements.- Photo-induced electron transfer at polyelectrolyte-water interface.- Luminescence study of fluidity in the L a mesophase and liquid phase of lead(II) decanoate.- Relaxation processes in polymeric electrolytes: Effect of the cation size and of the thermal history.- Mono- and multi-layers containing ion carriers.- Influence of surfactant concentration on the time-dependent rheological behavior of the lamellar liquid crystal.- Influence of organic counterions on the structure of lyotropic mesophases.- L 3 phases: Their structure and dynamic properties.- Alignment of lyotropic nematics by surface action.- Improved determination of the initial structure of liquid foams.- Surface characteristics of colloidal aluminas and barium titanates determined by inverse gas chromatography.- Impedance-spectroscopic investigations of water structure near silica surfaces.- Scaling laws for some physical properties of the L 3 phase.- Effect of halogeno substituted ethyl alcohols on the surface potential and on the surface tension at the water/air interface.- Two-dimensional model networks.- Domains formation in polymerized monolayers revealed by fluorescence microscopy.- Study of the swelling of latex particles by means of ultrasonic techniques.- Structure-reactivity relationship in langmuir-blodgett films of bisethylenedithio-tetrathiafulvalene (BEDT-TFF) derivatives.- p,T dependence of the hydrophobic interaction in a model solution.- The change in density and pressure tensor at the liquid-vapor interface.- Optical properties of Langmuir-Blodgett films: perylene excimer formation.- The influence of charged gel layers on the electrokinetic phenomena.- Direct approach of two particles covered with a porous layer.- Small-angle neutron scattering from dispersions of organophilic clays.- Low-angle static light scattering by fast aggregation of polystyrene latex.- Competition between micellization and adsorption of alkyl-PEO diblock copolymers on titanium dioxide particles.- Density dependence of the extinction coefficient of a dispersion of spherical metal particles.- Electrokinetic behavior of polyester and solid impurity during washing process in the presence of cellulose ethers and NTA.- Micelle shape and capacity of solubilization.- Electrokinetic characterization and colloid stability of calcium oxalate monohydrate dispersions in the presence of certain inhibitors.- Enzyme kinetic studies using lipase immobilised in microemulsion-based organogels.- Influence of the intensity of mixing on the droplet size distribution of emulsions: Theory and experiment.- Synthesis in situ in reverse micelle of copper metallic clusters.- Metal-ion complexation by micelle-solubilized long-chain complexing agents.- Precipitation of aluminum with surfactant in sea-water.- Comparison of charge numbers of interacting latex spheres from different experiments: Conductivity, electrophoresis, torsional resonance detection, and static light scattering.- Structural properties of dilute aqueous solutions of charged rods studied by light-scattering techniques.- Light scattering from aggregating colloids: Stretched exponential behavior of the time correlation function.- On the structure of suspensions of charged rodlike particles.- Structure and properties of partially neutralized poly(acrylic acid) gels.- Brownian dynamics close to a wall, measured by quasi-elastic light scattering from an evanescent wave.- Tracer-diffusion in binary mixtures of charged spherical macroparticles.- Structure and thermodynamics of mixtures of charged spherical colloidal particles.- The interaction between charged colloids with adsorbed polyelectrolytes.- Forced rayleigh scattering in mixtures of colloidal particles.- Analysis of alignments of colloidal spheres by light scattering.- The contribution of hydration forces to particle-particle interaction in a silica hydrosol.- Measurement and interpretation of counterion distribution around cylindrical polyelectrolytes.- Electrophoretic mobility, primary electroviscous effect and colloid stability of highly charged polystyrene latexes.- Yield stress in magnetic suspensions.- Role of the ionic strength in the viscosity of charged colloids.- Spectroscopic investigation on the effect of the addition of ceramide into lipid vesicles.- SANS in lysozyme solutions.- Changes in the percolation threshold by cytochrome c addition in AOT reverse micelles.- A study of the effect of different amino acids on the electrical properties of nitrofurantoin suspensions.- Effect of dimethylsulfoxide on the kinetics and thermodynamics of asymmetric phospholipid fluxes between magnetic and non-magnetic vesicles.- Molecular structure and dynamics of biopolymer gels by neutron scattering.- The ripple phase in model membrane systems.- Fluidity variation of DODAB vesicular membranes with estrogen hormone using the lucigenin chemiluminescent reaction.- Solubilization of lecithin vesicles by C12E8.- Osmotic coefficients of N-nonyl- and N-decyl-nicotinamide chloride surfactant aqueous solutions.- Hypersonic properties in macromolecular aqueous solutions.- Static and dynamic properties in thixotropic structures.- Study of temperature and pH effects on phase transition between liquid expanded/liquid condensed of cholesterol, lecithin and lithocholic acid mixed monolayers.- Study of non-ionic monoalkyl amphiphile-cholesterol vesicles solubilization by octylglucoside.- The use of a trace amount of methylated bovine serum albumin as a probe of the state of bovine serum albumin adsorbed on montmorillonite.- Microemulsions as a tool for enzymatic studies: The case of lipase.

We show that diffusing wave spectroscopy (DWS) permits the characterization of dynamic properties of concentrated colloidal suspensions on a large range of time– and length–scales ranging from a few angstroms to tens of nanometres. We focus in particular on the study of the aggregation and sol–gel transition in concentrated colloidal suspensions. We present a new technique to overcome the problem of nonergodicity in DWS of solid–like systems. Using this technique we obtain quantitative information about the microscopic dynamics all the way from an aggregating suspension to the final gel, thereby covering the whole sol–gel transition. At the gel point a dramatic change of the particle dynamics from diffusion to a subdiffusive arrested motion is observed. We combine DWS with small–angle neutron scattering and demonstrate that we can obtain an in situ characterization of the changes in the microstructure and the local particle dynamics as the system undergoes a sol–gel transition.

Molecular Interactions in Thin Films * Polymer-Surfactant Interactions * Structure and Dynamics at Interfaces * Biocolloids * Colloids in Pharmaceutical and Biological Applications * New Trends in Colloid and Interface Science Techniques * Rheology * Self Assembly of Amphiphiles * Measurements in Concentrated Suspensions.

Colloid science can be used to provide significant benefits in the design and manufacture of personal care, cosmetic, pharmaceutical and medical products and processes. It has been called the midwife of invention; somewhere in the function, formulation and processing necessary to achieve new and improved products the influence of colloid science, though sometimes hidden from the untrained eye, will be felt. Brian Vincent has contributed much to the fundamentals of this science, in particular pushing forward the theoretical boundaries. Paraphrasing Nobel laureate Richard Smalley, if colloid science research is the “garden of the physical sciences”, then Brian also has been a creative master gardener harvesting solutions to many a thorny problem (no pun intended). And, like a good artisan, he has passed on his skills to those who have been fortunate enough to have been called his students. That he is an excellent teacher is evident from the many eminent scientists worldwide continuing his legacy.Trained in this discipline, I have continued to work for nearly forty years, not as a scientist or as an academic but as an instrument designer, cosmetics formulator and salesperson. Unlike many in academe and industry I have not stayed “in one place” but have moved as new opportunities and new challenges arose. In so doing I became a “jack-of-all-trades” but have had the good fortune of never having been bored. My contribution to this book celebrating the career of Brian Vincent is thus as an eminent businessman who has dabbled in colloid science.My contact with Brian dates back to 1968, and so this chapter will first chart the early associations with him and then focus on a few examples of how I have used some practical facets of colloid science such as surface modification, encapsulation and coating to build a successful and, financially, extremely rewarding business. I will end with a couple of examples of how the application of colloid science might help in the fight against HIV/AIDS. Throughout Brian's career I have been privileged to have him as a friend and to be able to call on his vast experience in the field of colloid and interface science. Discussions with him were always lively and instructive; the help and advice he has given me over the years has been invaluable. He is the epitome of the truly eminent scientist.

This volume contains the proceedings of the VIIIth annual meeting of the European Colloid and Interface Society (ECIS) held in Montpellier, France, in September 1994. The contributions cover a broad range of fields in modern colloid science, as well as their technical, experimental and theoretical aspects. Specific emphasis is given to: mixed systems (amphiphilic phases incorporating foreign particles); concentrated suspensions and emulsions (structure and mechanical properties); interactions and long-range order; supramolecular structures under flow; and bio-colloids.

This special issue of the Australian Journal of Chemistry comprises a selection of papers from the program of the Australian Colloid and Interface Symposium (ACIS), which was held at Coogee Beach, Sydney from 4 to 8 February 2007. The conference was chaired by Professor Roger Horn from the Ian Wark Research Institute at the University of South Australia. Over 240 scientists gathered at Coogee for this meeting, including 93 international guests from over 20 different countries and 150 Australians from almost every state inAustralia.The weather was excellent during the conference, but, as the conference attendees arrived at Coogee, unfortunately so too did about 6000 bluebottles, who also arrived to enjoy the beautiful local waters. Ironically, the bluebottles left at about the same time as the bulk of the conference delegates. The ACIS 2007 program highlighted current research in colloid and interface science from both fundamental and technological viewpoints, as well as highlighting some of the exciting new areas in which the discipline is having a substantial impact. This year’s themes were Spectroscopy and Scattering in Surface and Colloid Science (chaired by David Beattie, Ian Wark Research Institute, and Jim McQuillan, University of Otago), which drew attention to the opportunities for studying colloidal and interfacial interactions using either spectroscopic or scattering techniques, with the latter particularly focussed towards the Australian Synchrotron and the Opal Replacement Reactor. The theme of Surface Forces, Nanotribology and Biological Interactions (chaired by Michelle Gee, University of Melbourne, and Roger Horn, Ian Wark Research Institute) honoured the work of Professor Jacob Israelachvili (Fig. 1), including his seminal research in surface forces undertaken at the Australian National University in the late 1970s and early 1980s. The Inorganic Oxide Surfaces theme (chaired by George Franks, University of Melbourne, Jonas Addai-Mensah, Ian Wark Research Institute,

There is a big gap between idealized colloid science and the needs of a printing ink formulator. This often leads to formulations based on intuition and experience rather than good science. By bringing together the most relevant colloid and interface science with the capabilities of modern apps, it is possible to bridge the gap between theory and reality to the benefit of both the colloid science community and those who need the science to improve their formulations. The process of making current science usable also exposes the limitations of available theories. This suggests a methodology for highlighting the grand challenges to the colloid science research community, including the challenge of making any new science more usable.

The subject of this book is the rheology of colloidal and nanoparticle dispersions. The reader will quickly appreciate the breadth of the subject area and, furthermore, that mastering colloidal suspension rheology requires some basic knowledge in colloid science as well as rheology. Thus, this chapter introduces some basic and simplified concepts in colloid science and rheology prior to embarking on the main theme of the book. As the term colloid is very general we necessarily need to focus on fundamental aspects of basic colloidal particles, their interactions, and their dispersion thermodynamic properties. These are, of course, the basis for understanding more complex systems. The rheology section is provided as an introduction to the basic concepts (a more advanced treatment of rheological testing of colloidal dispersions is provided in Chapter 9). Therefore, this chapter provides the minimum level of understanding that the reader will find valuable for understanding colloidal suspension rheology, as well as a means to introduce nomenclature and concepts used throughout the book. As a consequence, a reader familiar with either or both subjects may still find it valuable to skim through the material or refer back to it as needed. Colloidal phenomena Colloid science is a rich field with an equally rich literature. The reader is referred to a number of excellent monographs that cover the basics of colloid science in much greater detail. These will be presented without derivation. In particular, we use nomenclature and presentation of many ideas following Colloidal Dispersions [1] and Principles of Colloid and Surface Chemistry [2], which may be of help for further reading and inquiry, and for derivations of the results presented herein. Indeed, there are many additional excellent textbooks and monographs on colloid science, and references are provided where they are most relevant throughout this chapter as well as in the other chapters.