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How complex is the self-assembling of polyion-surfactant complex salts ?

Watson Loh Institute of Chemistry, Universidade Estadual de Campinas (UNICAMP), Campinas, SP, Brazil

Oppositely-charged surfactants and polyelectrolytes are considered a rather complex mixture due to the effects of their strong association onto their phase behavior, most notably phase separation and self-assembling. During the last few years, our group has been using the approach proposed by Piculell and coworkers of preparing so called complex salts composed of the surfactant and polyion. Such chemical species have been prepared with different polyelectrolytes and surfactants and their phase behavior in binary or ternary (addition of oils, especially alcohols) mixtures was determined. Phase diagrams and structural analyses (carried out using mostly SAXS and diffusion measurements) produced rich information on the effect of the polymeric counterion on surfactant association.
This presentation will summarize some of these results for complex salts of different polyions (homopolymer and block-copolymers) and In the presence of different oils, with emphasis on generalizations that were possible through the use of this new methodology. These comprise the possibility of mesophase formation at much lower surfactant concentrations, with lower water contents and of tailoring mesophase geometry and structure by selecting appropriate system. Additionally, properties of water and oil-soluble complex salts assemblies will be described.