ABSTRACT CTS-9410147 Nicholas Abbott/U. Cal @ Davis Studies of water-soluble surfactant molecules have, in the past, largely concentrated on systems in which the amphiphilicity of each surfactant was fixed at the time of its synthesis; at fixed temperature, pressure and composition, the properties of systems containing these surfactants are invariant. The research proposed here moves to active control of amphiphilicity, and aims to explore molecular-level principles to change, in situ and reversibly, the amphiphilicity of molecules and thereby control the surfactant-based properties of solutions and interfaces. Amphiphiles with redox-active groups that change hydrophilicity with oxidation state will designed and synthesized. Electrochemical and photochemical techniques will be used to control, in situ, the oxidation states of redox-wettability, micellization, and macroscopic phase-behavior of their solutions. The proposed research aims to develop the capability to cycle, on time-scale of seconds, properties of aqueous surfactant solutions and to direct changes in amphiphilicity to specific regions of a solution or interface thereby creating spatial gradients in their surfactant-based properties. The fundamental relationships between the molecular structures of surfactants and their collective properties will be investigated.
