Dynamic Aggregation Behavior of Surfactant Mixtures in Solutions and at Solid/liquid Interfaces

Columbia University, New York NY

Investigators

Abstract

ABSTRACT CTS-0089530 Columbia University The goal of the proposed research is to investigate the formation of surfactant aggregates in mixed systems and particularly the dynamics involved. As the experimental system is complex the strategy involves use of multi-pronged approach, combining several techniques such as ultra-filtration, analytical, centrifuge, micro-calorimetry and AFM, with advanced spectroscopic techniques including Surface Plasmon Resonance Spectroscopy, fluorescence and ESR. The goal is to determine the relationship between structures of surfactants and their properties as determined by the shape, composition and structure of mixed micelles and hemimicelles. Based on these results a recent theoretical model will be refined to enable prediction of the formation of surfactant aggregates in their mixtures and changes in them. Surfactants to be studied in this proposal will include environmentally benign sugar-based and pyrrolidone-type surfactants. The investigators have seen that these surfactants do show unusual selectivity in their adsorption on solids, but the reasons for the selectivity are not known. Similarly, another important example is the synergy observed between the thiol surfactants in flotation, which is not well understood. Study of their synergy will be a collaborative effort between us and the University of Cape Town, South Africa group which has been studying the issue from a thermodynamic point of view. The proposed research will enable the investigators to advance the frontiers of surfactant colloidal chemistry by acquiring new information on the formation of surfactant aggregates in their mixtures. Such information will make it possible to develop opportunities to fully utilize the unique nano-environment provided by mixed surfactant aggregates for particle processing, ultra-purification, reactions in nano-domains as well as controlled release from such domains.