Progress in Colloid & Polymer Science • Vol. 81 PROGRESS IN COLLOID & POLYMER SCIENCE Editors: H.-G. Kilian (Ulm) and G. Lagaly (Kiel) Volume 81 (1990) Trends in Colloid and Interface Science IV Guest Editors: M. Zulauf (Basel), P. Lindner and P. Terech (Grenoble) Steinkopff Verlag • Darmstadt 0 Springer-Verlag. New York ISBN 3-7985-0839-9 ISBN 0-387-91368-8 ISSN 0340-255-X This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically these rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in other ways, and storage in data banks. Duplication of this publication or parts thereof is only permitted under the provisions of the German Copyright Law of September 9, 1965, in its version of June 24, 1985, and a copyright fee must always be paid. Violations fall under the prosecution act of the German Copyright Law. © 1990 by Dr. Dietrich Steinkopff Verlag GmbH & Co. KG, Darmstadt. Chemistry editor: Dr. Maria Magdalena Nabbe; English editor: James Willis; Production: Holger Frey. Printed in Germany. The use of registered names, trademarks, etc. in this publication does not imply, even in the absence of specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. Type-Setting: Graphische Texterfassung, Hans Vilhard, D-6126 Brombachtal Printing: betz-druck gmbh, D-6100 Darmstadt 12 Preface When the executives of the European Colloid and The conference was hold at the Congress Center of Interface Society (ECIS) decided to have the Third F. Hoffmann-La Roche. We are much indebted to ECIS Meeting in Switzerland, they found that their those responsible and to the executives of the company collegues at the Institut Laue-Langevin (ILL) had an- for the generous support extended to us in preparing nounced a Workshop on "Structure and Dynamics of and running the conference. We gratefully acknowl- Colloid Systems" in Grenoble. It seemed natural for edge financial help from: Institut Laue-Langevin, both parties to join forces, and thus a combined ECIS Hoffmann-La Roche, Ciba-Geigy, and Sandoz. The Conference & ILL Workshop was held in Basel. It scientific program was established under the wise was attended by nearly 250 scientists representing the guidance of an efficient program committee compris- major groups working in the field in Europe, but also ing M. Corti, H.-F. Eicke, D. Langevin, D. Richter, some groups from other countries. Roughly 90% of and A. Vrij. the oral contributions given at the meeting are pub- On behalf of ECIS and ILL, we would like to thank lished here in their written version. They appear in all the participants of the meeting for their brilliant the order that they were presented in the meeting, contributions and stimulating discussions. Certainly within the loosely defined framework of topics. We they inspired a lot of cooperation among colloid scien- hope that both the attendants in Basel and those who could not be there read and reread them with pleasure tists, which is, of course, one of the aims of ECIS. and profit! About 80 posters are covered in this volume by very short abstracts. They appear in alphabetical order of Martin Zulauf the submitting author's name. We regret that those Peter Lindner works had to be abbreviated due to space restrictions. Pierre Terech Contents VII Contents Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V Micelles and mesophases Ottewill RH, Rennie AR, Schofield A: The effect of electric fields on nonaqueous dispersions . . . . . . . . . . . . . . . . 1 Charvolin J: Crystals of fluid films in systems of amphiphiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Almgren M, Alsins J: Fluorescence quenching in the CnE6-water system: Diffusion-control in three to zero dimensions 9 Appell J, Bassereau P, Marignan J, Porte G: Polymorphism in dilute surfactant solutions: A neutron scattering study 13 Schurtenberger P, Scatazzini R, Magid LJ, Leser M, Luisi PL: Structure and dynamics of polymerlike reverse micelles 19 Microemulsions Zemb TN, Barnes IS, Derian P-J, Ninham BW: Scattering as a critical test of microemulsion structural models . . 20 Chen SH, Chang SL, Strey R: On the interpretation of scattering peaks from bicontinuous microemulsions . . . . . 30 Aveyard R, Binks BP, Cooper P, Fletcher PDI: Mixing of oils with surfactant monolayers . . . . . . . . . . . . . . . . . 36 Eriksson JC, Ljunggren S: The multiple chemical equilibrium approach to the theory of droplet microemulsions.. 41 Radiman S, Fountain LE, Toprakcioglu C, de Vallera A, Chieux P: SANS study of polymer-containing micro- emulsions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 Dynamics Farago B, Huang JS, Richter D, Safran SA, Milner ST: Microemulsion shape fluctuation measured by neutron spin echo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 Magid LJ, Weber R, Leser ME, Farago B: Control of curvature in microemulsions: The AOT/Kryptofix couple . . 64 M616ard P, Mitov MD, Faucon JF, Bothorel P: Bending elasticity and dynamical fluctuations of giant lipidic vesicles 68 Huang JS, Ye L, Weitz DA, Ping Sheng, Bhattacharya S, Higgins M J: Dynamic rigidity percolation of inverted AOT micellar solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 Schulz SF, Maier EE, Krause R, Weber R: Dynamic light scattering on liquid-like polyelectrolyte solutions: Cor- relation spectroscopy on dilute solutions of virus particles at very low ionic strength . . . . . . . . . . . . . . . . . . . . 76 Holtzscherer C, Candau F, Ottewill RH: A small-angle neutron scattering study on AOT/toluene/(water + acryl- amide) micellar solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 Bucci S, Hoffmann H, Platz G: Diffusion of latex particles in viscoelastic surfactant solutions . . . . . . . . . . . . . . . 87 Piazza R, Stavans J, Bellini T, Lenti D, Visca M, Degiorgio V: Light-scattering experiment on anisotropic spherical particles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 Felderhof BU: Hydrodynamic interactions in suspensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 Colloidal systems and non-equilibrium conditions Hess S, Loose W: Shear-flow-induced structural changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 Baumann J, Hertel G, Hoffmann H, Ibel K, Jindal V, Kalus J, Lindner P, Neubauer G, Pilsl H, Ulbricht W, Schmelzer U: Time-dependent small-angle neutron measurements of aligned micelles . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 Lindner P, Bewersdorff HW, Heen R, Sittart P, Thiel H, Langowski J, Oberthiir R: Drag-reducing surfactant solutions in laminar and turbulent flow investigated by small-angle neutron scattering and light scattering . . . . . . . . . . . 107 van der Werff JC, de Kruif CG: The rheology of hard-sphere dispersions: The micro-structure as a function of shear rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 Mimouni Z, Bossis G, Mathis C, Meunier A, Paparoditis C: Field-induced structure in a colloidal suspension . . . 120 Additives to colloids and applications Gerber H: Interactions between direct dyes in the dyeing of cellulosic substrates . . . . . . . . . . . . . . . . . . . . . . . . . 126 Ravey JC, Espinat D: Macrostructure of petroleum asphaltenes by small angle neutron scattering . . . . . . . . . . . . 127 VIII Co n t e n t s Schom/icker R: Chemical reactions in microemulsions: Tracing the progress of a reaction from the influence of the reactants on the phase behaviour . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131 Sz6nyi S, Sz6nyi F, Sz6nyi I, Cambon PA: Modification of water-soluble polymers constituting multipurpose fire- fighting foams by new reactive fluorinated surfactants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136 Prochaska K, Szymanowski J: Adsorption of 5,8-diethyl-7-hydroxydodecan-6-oxime at toluene/water interface and the rate of copper extraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140 Solans C, P6s MA, Azemar N, Infante MR: Lipoaminoacid surfactants: Phase behavior of long chain N~-Acyl arginine methyl esters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144 Glatter O, Spurej E: Activation studies on human platelets using electrophoretic and quasi-elastic light scattering. 151 Horisberger M: Quantitative aspects of labelling colloidal gold with proteins in immunocytochemistry . . . . . . . . . 156 Aggregates, ordering and structural transitions Klein R, Weitz DA, Lin MY, Lindsay HM, Ball RC, Meakin P: Theory of scattering from colloidal aggregates . . 161 Pefferkorn E, Widmaier J, Graillat C, Varoqui R: Dynamic scaling in colloid aggregation reaction limited process induced by electrolytes and polyelectrolytes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169 Rouw PW, de Kruif CG, Vrij A: Scattering properties of lyophilic colloidal silica particles in non-polar solvents. Effects of attraction forces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174 Joanicot M, Wong K, Maquet J, Chevalier Y, Pichot C, Graillat C, Lindner P, Rios L, Cabane B: Ordering of latex particles during film formation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175 Pistoor N, Kremer K: Molecular dynamics simulations of colloids: Supercooled Yukawa systems . . . . . . . . . . . . . 184 Seddon JM, Hogan JL, Warrender NA, Pebay-Peyroula E: Structural studies of phospholipid cubic phases . . . . . 189 Films, membranes, surfaces and wetting Penfold J: The use of the specular reflection of neutrons to study surfaces and interfaces . . . . . . . . . . . . . . . . . . . 198 Lee EM, Thomas RK, Rennie AR: The specular reflection of neutrons from interfacial systems . . . . . . . . . . . . . . 203 Lee LT, Langevin D, Meunier J, Wong K, Cabane B: Film bending elasticity in microemutsions made with nonionic surfactants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209 Strey R, Kahlweit M: Microemulsions - A qualitative thermodynamic approach . . . . . . . . . . . . . . . . . . . . . . . . 215 Winter R, Thiyagarajan P: High-pressure phase transitions in model biomembranes . . . . . . . . . . . . . . . . . . . . . . 216 Rolandi R, Ricci D: Photovoltages in bilayer lipid membranes incorporation cadmium sulfide particles . . . . . . . . 222 Hjelm RP, Thiyagaragan P, Silvia DS, Lindner P, Alkan H, Schwahn D: Small-angle neutron scattering from aqeuous mixed colloids of lecithin and bile salt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225 Braganza LF, Crawford R J, Smalley MV, Thomas RK: A study of the swelling of n-butylammonium vermiculite in water by neutron diffraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232 Malliaris A: Global fluorescence analysis in micellar systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238 Zimmermann F, Wokaun A: Characterization of silver colloid stabilization by surface enhanced Raman scattering (SERS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242 Abstracts Adelbert P, Dreyfus B, Gebel G, Nakamura N, Pineri M, Volino F: Structure of perfluorinated ionomer solutions 248 Bewersdorff H-W: Drag reduction in surfactant solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248 Mathew C, Saidi Z, Peyrelasse J, Bonded C: Waterless ternary microemulsions: Viscosity, dielectric relaxation and conductivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249 Borkovec M: Role of stretching and bending energies in the transition from micelles to swollen microemulsion droplets: Interfacial tensions, size distributions and shape fluctuations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250 Bossis G, Lemaire E, Mathis C, Mimouni Z, Paparoditis C: Magnetoviscosity of colloidal suspensions . . . . . . . . . 251 Cametti C, Codastefano P, Tartaglia P, Rouch J, Chen SH: Percolation in water-in-oil microemulsions. Low- frequency electrical conductivity measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251 Collin D, Kern F, Candau F: Rheological behavior of copolymer latexes prepared in inverse microemulsions . . . . 252 Canselier JP, Pellegatta JL, Monfort JP: Cosurfactant structure and solubilization properties of middle-phase mi- croemulsions. Application of the pseudophase model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 Cao A, Hantz-Brachet E, Taillandier E: Effect of D-Propanolol on neutral phospholipidic liposomes . . . . . . . . . . 254 Cichocki B, Hinsen K: Dynamical computer simulation of concentrated hard sphere suspensions . . . . . . . . . . . . . 254 Meziani A, Touraud D, Clausse M: Alkanals versus alkanols as microemulsion cosurfactants . . . . . . . . . . . . . . . . 255 Clausse M, Touraud D: Realm-of-existence and electroconductive behavior of water/ionic surfactant/alkanol/hydro- carbon microemulsions. Influence of the hydrocarbon nature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255 D'Aguanno B, Klein R: Structural effects of polydispersity in charged colloidal suspensions: A comparison of ex- perimental results with integral equation theories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256 de Kruif CG: The gas-liquid phase separation in colloidal dispersions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257 Denkinger P, Kunz M, Burchard W: Spherical and rodlike micelles from non-ionic surfactants with oligosaccharide head-groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257 Contents IX Djakovi6 Lj, ~ever I, Djakovi6 T: Flow equations of real colloidal systems derived by the chemical kinetics methods 258 Domazou AS, Mantaka-Marketou AE: Influence of 17a-ethinylestradiol on the fluidity, polarity and size of DDAB vesicles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258 Dufourc E J, Campos A, Abad C, Laroche G, P6zolet M, Dufourcq J: Interaction of basic peptides with negatively charged biological model membranes. A 31p. and 2H-NMR study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259 Delnomdedieu M, Boudou A, Georgescauld D, Dufourc E J: Mercury NMR. A tool to investigate the chemical structure of mercury compounds in solution and to follow binding phenomena to membrane systems . . . . . . . . 259 Bedeaux D, Borkovec M, Eicke H-F, Hilfiker R, van der Linden E: Rigidities and dynamics of shape fluctuations in dilute AOT-microemulsions by Kerr effect measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260 Fagotti C, Heenan RK: Small-angle neutron scattering of ethoxylated sodium alkylcarboxylates surfactants . . . . . 261 Bettarini S, Bonosi F, Gabrielli G, Puggelli M: Langmuir Blodgett films containing metal ions . . . . . . . . . . . . . . 261 Margheri E, Niccolai A, Lo Nostro P, Gabrielli G: Monolayers and bilayers of lipids as models of biological membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262 Borbely S, Cser L, Gladkih IA, Ostanevich YM, Vass S: Small angle neutron scattering (SANS) investigations of sodium alkyl sulfate micelles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262 Glatter O, Schnablegger H, Sieberer J: A comparative study on different techniques and evaluation methods for sizing of colloidal systems using light-scattering techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263 Gottis P-G, Lalanne J-R: Coupling or radial and orientational orders between colloidal particles in asphaltenes solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263 Hanssen JE, Meling T, Jakobsen KR: Interaction of gas-blocking foam with oil in model porous media . . . . . . . . 264 Hiltrop K: Iridescent colours of a surfactant in water at very high dilution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265 Wanka G, Hoffmann H, Ulbricht W: The aggregation behaviour of triblock copolymers of ethylene oxide and propylene oxide in aqueous solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266 Atkinson P J, Heenan RK, Grimson M J, Howe AM, Robinson BH: Structure of microemulsion-based organo-gels 266 Huber K, Hall M: Interfacial behavior of binary surfactant mixtures in aqueous solution . . . . . . . . . . . . . . . . . . . 267 Hfidicke E, Hahn K, Ley G, Streib J, Lindner P: SANS studies on the distribution of surfactants in latex films . . . 267 Alavi F, Jones RB: Rotational diffusion of a tracer particle in a magnetic field . . . . . . . . . . . . . . . . . . . . . . . . . . . 268 Akesson T, Woodward C, J6nsson B: Electric double layer forces in the presence of polyelectrolytes . . . . . . . . . . 268 Laggner P, Kriechbaum M, Rapp G, Hendrix J: Structural pathways and short-lived intermediates in phospholipid phase-transitions. Millisecond synchrotron x-ray diffraction studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 268 Langowski J, Bryan R: A new maximum entropy algorithm for the analysis of dynamic light-scattering data: Ap- plication to particle distribution and DNA internal motions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269 Lin T-L, Chen S-H, Roberts MF: Theory and small-angle neutron scattering studies of the rod-to-sphere transition of diheptanoyl-PC micelles solubilizing tributyrin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 270 Ldpez Quintela MA, Fernfindez Ndva A, Liz L: Hydrodynamic instabilities in microemulsions . . . . . . . . . . . . . . 270 Aveyard R, Binks BP, Fletcher PDI, Lu JR: The resolutions of water-in-crude-oil emulsions by the addition of low molar mass demulsifiers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271 Majolino D, Mallamace F, Migliardo P, Micali N, Vasi C: Viscosity measurements in dense microemulsions, evidence of aggregation processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271 Marcozzi G, Caselli M, Luisi PL: Use of reverse micelles for the extraction of proteins . . . . . . . . . . . . . . . . . . . . 272 Marion G, E1 Ahmadi S, Graciaa A, Lachaise J: Dynamic light scattering in middle phase microemulsions: Detection of the oil-in-water/bicontinuous transition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272 Masson G, Iseli F: The role of hydrocolloids in the stabilization of oil-in-water emulsions for enteral nutrition . . . 273 Mendiboure B, Graciaa A, Lachaise J, Marion G, Salager JL: Emulsion formation: A stochastic model to forecast the drop size distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 274 Middendorf HD, Cavatorta F, Deriu A: Small-angle neutron scattering from polysaccharide gels . . . . . . . . . . . . . 274 Mossa G, Annesini MC, Di Giutio A, Finazzi-Agr6 A: Liposomes as bioreactors: Transport/kinetic phenomena . . 275 Hadzianestis J, Nikokavouras J: Chemiluminescence of 9-(p-methyl)-benzylidene-9,10-dihydro-10-methylacridine in CTAC micelles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276 Strey R, Schomaecker R, Roux D, Nallet F, Olsson U: Phase diagram of the water-Ci2E5 system: Extension and properties of the L3 and dilute lamellar phases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276 Gorski NI, Ostanevich YM: Investigation of the structure of reversed micelles in a AOT + C6 (H, D)6 + D20 system by small-angle scattering (SANS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277 Paillette M: Experimental survey of the dynamic on the electrical charges in a water-in-oil microemulsion . . . . . . 277 Deggelmann M, Palberg T, Leiderer P, Versmold H, Weber R: Electrophilic light scattering in ordered colloidal suspensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278 Penfold J, Staples E, Cummins PG: Small-angle neutron scattering from anisotropic micelles aligned by shear flow 279 Penfold J, Staples E, Cummins PG: The nature of adsorbed layers of nonionic surfactants on sol particles . . . . . . 280 Petit C, Zemb T, Pileni MP: Structure of apolar gels at the sol~gel transition point . . . . . . . . . . . . . . . . . . . . . . . 28~ Ri6ka J, Borkovec M, Hofmeier U, Eicke H-F: Time-correlated photon counting and self-diffusion in concentrated microemulsions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282 Sadaghiani AS, Khan A: Solution structures of catanionic surfactant systems . . . . . . . . . . . . . . . . . . . . . . . . . . . 283 Scartazzini R, Schurtenberger P, Luisi PL: Phase behaviour and viscoelastic properties of lecithin reverse micelles 283 X Contents Lendinara L, Senatra D, Giri MG: 1H magnetic resonance relaxation study - low-resolution technique - of water- in-hexadecane microemulsions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284 Smits C, Dhont JKG, Lekkerker HNW: Influence of the presence of non-adsorbing polymer on the crystallization phenomena of colloidal dispersions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284 Wigniewski M, Szymanowski J: Adsorption of model 4-alkylphenylamines at aqueous/organic interfaces and the rate of palladium (II) extraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285 Oshima R, Takada M, Tsuchiya S, Miyakoshi T, Seno M, Ebert G: Oxidation of urushiol homologues by Rhus laccase in microemulsions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 286 Terech P: Surfactant aggregation in hydrocarbons: Solvent-induced structural variations in physical steroid gels . . 286 Tezak D, Strajnar F, Fischer-Palkovic I: Temperature dependence of solubility and the liquid crystal formation in aqueous solutions of metal-dodecylbenzenesulfonates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287 Filipovi6 N, Tomagi6 V: Mixed micelle formation and precipitation in mixture of anionic and cationic surfactants 288 Tondre C, Kim HS, Claude B: Effect of linear and micelle-like polyelectrolytes on the kinetics of reduction of dialkyl- viologens by dithionite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 288 Radiman S, Toprakcioglu C, Raedler JO, de Vallera A, Hjelm Jr. RP: Structural investigation of liquid crystalline phases of ternary surfactant systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289 Field JB, Toprakcioglu C, Ball RC, Stanley H, Rennie A, Penfold J, Barford W: Neutron reflection investigation of polymer layers adsorbed at the solid-liquid interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 290 Traber RH, Fehlbaum M: Improvement of wicking flow of surfactant solutions in fabrics by the use of cosurfactants 29i Vass S: Use of thermodynamic and nuclear/SANS, positron annihilation/methods in the investigation of alkylsulphate micelles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 291 Wagner NJ, Klein R: The rheology and microstructure of charged suspensions . . . . . . . . . . . . . . . . . . . . . . . . . . 292 Han D, Peng P, Walde P, Luisi PL: Dependence of enzyme activity and conformation on water content in reverse micelles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292 Baaken C, Belkoura L, Fusenig S, Mi.iller-Kirschbaum T, Woermann D: Study of 2-butoxyethanol/water mixtures of critical composition in the vicinity of the lower critical point: measurements of light scattering and ultrasonic absorption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293 Wolff T, Emming C-S, KlauBner B, von Biinau G: In situ viscosity changes and phase transitions in cationic and non-ionic aqueous surfactant systems triggered via photoreactions of solubilizates . . . . . . . . . . . . . . . . . . . . . . 294 Xenakis A, Cazianis CT, Matliaris A: Nonionic microemulsions as model of biosystems studied by probing techniques 295 Dubois M, Zemb T: Transition of a disordered random bilayer to a swollen lamellar liquid crystal . . . . . . . . . . . 296 Schmidt D, Colombo VE, Zulauf M: Colloidal particles with dodecahedral symmetry formed spontaneously by lecithin, bile salts, cholesterol and a plant saponin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 297 Author Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 298 Subject Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300 Progress in Colloid & Polymer Science Progr Colloid Polym Sci 81:1 - 5 (1990) The effect of electric fields on nonaqueous dispersions R. H. OttewilP), A. R. Rennie 2) and A. Schofield 1) 1) School of Chemistry, University of Bristol, UK 2) Institut Laue Langevin, Grenoble, France Abstract: Small angle neutron scattering has been used to investigate the struc- ture of poly(methylmethacrylate) dispersions in dodecane in the presence of an electric field. In dodecane alone field effects were not observed. In the presence of calcium octanoate, however, the particles apparently become charged and increased ordering was observed. The effect of an electric field on the latter dispersions produced an anisotropy of structure which suggested that the par- ticles were forming loose "strings of beads" in the direction of the applied field. Key words: Neutron s_cattering; polymer latices; _nonaqueous _dispersions; electric _fields; m_i crostructure Introduction NUOSYN CALCIUM 10% was obtained from Durham Chemicals Limited, Birtley, Chester-le-Street, Co. Durham, U.K. According to the manufacturers this is a solution of The effects of electric fields on nonaqueous disper- calcium iso-octanoates in a hydrocarbon medium. It is re- sions have been rather sparsely studied in comparison ported in this communication as calcium octanoate. to studies carried out on aqueous systems. However, The polymer latex, SPSO90, was prepared by the disper- the availability of monodisperse spherical polymer sion polymerisation technique previously described [2]. The number average particle diameter determined by electron particles at high volume fractions in media of low microscopy was 0.20 gm and the weight average diameter relative permittivity [1, 2] has provided excellent sys- determined by small angle neutron scattering was 0.22 gm tems for fundamental studies [3, 4]. Moreover, the de- [5]. velopment of small angle neutron scattering has pro- vided a means of studying the structure of concen- Small angle neutron scattering trated colloidal systems in applied fields and has The small angle scattering measurements were carried out already been used to examine systems of this type using the neutron diffractometer D I 1, at the Institut Laue under shear fields [5, 9]. Langevin, Grenoble [10], with a sample-detector distance of In this communicat ion we provide a brief report on 35.7 m and a neutron beam wavelength of 0.80 nm. For the use of small angle neutron scattering to investigate elastic scattering measurements, the magnitude of the scat- the effect of applied electric fields on the microstruc- tering vector, Q, is defined by, ture of dispersions of poly(methylmethacrylate) par- Q = 4 rc sin (0/2)/2 ticles stabilised by poly (12-hydroxystearic acid) in a hydrocarbon medium. In the first instance the parti- with 0 = the angle between the incident and the scattered cles were examined in dodecane alone and then in beams. The measurements were carried out in an optical-standard dodecane with the addition of small amounts of cal- quartz cell with a pathlength of I ram. Bright platinum rods cium octanoate to provide some conductance to the were inserted into the cell at a separation distance of 6 mm. dispersion medium. An A.C. field of frequency 50 Hz was applied across the electrodes. The applied voltage was varied from zero to 1800 V. The experimental arrangement is illustrated sche- Experimental matically in Fig. 1. The neutron beam, of diameter 4 mm, passed between the electrodes in a direction perpendicular Materials to the applied electric field. The scattered neutrons were measured using a two-di- Dodecane was B.D.H. material. mensional detector, a square matrix of 64 x 64 elements. 2 Progress in Colloid & Polymer Science, Vol. 8t (1990) Electrodes Detector ~ 1600 m % Incident Beam , ~ 800 Beam stop 0,002 0,004 0.006 Q/Aq Fig. 1. Experimental arrangement used for examining the small angle neutron scattering from a polymer colloid dis- Fig. 2. Intensity, I(Q), against scattering vector, Q, for a 40% persion during the application of an electric field w/w poly(methylmethacrylate) latex dispersion: - O - , in dodecane; - A - , in dodecane containing 0.1% calcium oc- tanoate This allowed either two-dimensional contour plots to be obtained showing lines of equal intensity or three-dimen- sional plots showing the intensity across the detector. For isotropic two-dimensional patterns the intensities can read- and the samples were essentially in the same medium, ily be radially averaged to give one-dimensional plots of intensity, I(Q), against Q. Anisotropy of the sample can be A also remained constant. Thus the changes in the clearly recognised in a contour plot. In this case in order to scattering curve were attributed to changes in S(Q). obtain plots of I(Q) against Q the averaging procedure can The changes in shape indicated an increase in inter- be restricted to small sectors, for example, parallel (0 ___ 15 °) action between the particles with the implication that and perpendicular (90 + 15 °) to the direction of the applied field [l 1]. this arose because the addition of calcium octanoate caused the particles to acquire a weak electrical charge. This led to the form of the interaction chang- ing from that between sterically stabilised particles, a Results short-range repulsion, to that between electrically charged particles, a long-range repulsion. In the latter Intensity measurements without an electric field case the system becomes more ordered at the same volume fraction, and hence the peak in I(Q) against The intensity of scattering at a particular value of Q becomes more clearly defined. Electrophoresis Q is, for spherical particles, given by [3, 4], measurements on dilute dispersions confirmed that in the presence of calcium octanoate the particles had a I(Q) = A ¢ VpP(Q)S(Q) positive mobility. where for spheres of the core-shell type A contains instrumental constants, and terms in coherent scat- tering length density described elsewhere, [3], Vp = The effect of an electric field the particle volume, ¢ = volume fraction of the par- ticles, P(Q) = the particle shape factor and S(Q) = the structure factor. Calcium octanoate absent Figure 2 shows a curve for a 40% w/w dispersion of the latex SPSO90 in dodecane. This shows a broad peak consistent with short-range interactions of the Figure 3 shows the 2-dimensional contour plots ob- hard sphere type examined in earlier work on poly- tained using an 18% w/w dispersion of poly(methyl- methylmethacrylate latices [ 3 - 5 ] . The addition of methacrylate) particles in dodecane alone. The pattern calcium octanoate to the sample caused a substantial obtained from latex in the absence of the field is shown change in the form of the curve. As can be seen from in Fig. 3 a, and that with a field strength of 3800 V Fig. 2, the broad peak of the original latex became cm -1 applied is shown in Fig. 3b. No discernable very much narrower and sharper. Since the basic latex change in the pattern was observed on the application was the same in both cases, i.e. P(Q) was the same, of the field.