Comparative analysis of complex liquids based on a multi-experimental approach.
A parallel analysis is here presented between the results gathered by the author by means of three different experimental approaches--Dielectric analysis, Thermally Stimulated Depolarization (TSD) and Differential Scanning Calorimetry (DSC)--on some multi-component complex liquids consisting of association structures of self-assembling amphiphiles as, water-in-oil microemulsions. The highly dispersed nature of these systems was evidenced with the dielectric study: a Maxwell-Wagner relaxation was found to characterize this type of systems. The structural evolution of the system, against water addition, was well described by the orientational processes induced in the liquid samples by a nearly static electric field as in the TSD method. The investigation by DSC, besides offering a basic picture of the system's thermodynamics, allowed the measure of the specific heat, at constant pressure, at the higher order percolative phase transition. The comparison between the results obtained on samples processed with identical thermal cycles, once under the action of an impressed electric field as in TSD, and, once in the absence of any impressed electric field as in DSC, did help distinguish three main concentration intervals within which structurally different systems form namely, isotropic microemulsions and two liquid crystalline structures of lyotropic type.
SANS analysis of perfluoropolyether water-in-oil microemulsions by hard sphere and adhesive hard sphere potentials

Abstract.Ternary water-in-oil microemulsions formed from an ammonium carboxylate PFPE surfactant of molecular weight 710 and a PFPE oil of molecular weight 900, leading to microemulsions that show a dynamic percolation phenomenon, were investigated by SANS to characterize the microstructure. Hard sphere and adhesive hard sphere potentials were used to model the droplet–droplet interactions assuming polydispersed droplets with a Schultz distribution of sizes.
Perfluoropolyether microemulsions: Conductivity behaviour of four-component water-in-oil systems
Abstract The solubilization of water in a perfluoropolyether (PFPE) oil by a PFPE carboxylic surfactant is studied by performing conductivity measurements in the presence of ethanol, butanol, hexanol, nonanol and a PFPE alcohol. The insolubility of any alkanol in the PFPE oil enables the confinement of the fourth component in the aqueous phase, in the PFPE oil or at the interface. The electroconductive behaviour of the corresponding water-surfactant-oil system, quantitatively described previously (A. Chittofrati, A. Sanguineti, M. Visca and N. Kallay, Colloids Surfaces, 63 (1992) 219), is the basis for discussion of the data. The results provide evidence for the role of the fourth component in the competition between charge fluctuation among closed water domains (droplets) and migration of hydrated/partially dissociated ionic species (counterions) in solution: one of the two conduction mechanisms becomes predominant, depending on the type of alcohol. The electroconductive properties mirror the structure-maker/breaker effect of each alcohol on the association of this PFPE surfactant, in analogy with hydrocarbon systems. The similarities between four-component PFPE systems and the corresponding three-component PFPE system upon variation of the packing parameter (V/al as defined by Ninham and co-workers (J. Chem. Soc., Faraday Trans. 2, 72 (1976) 1525; 76 (1980) 201)) are discussed in detail.