Microemulsion structure and its effect on electrochemical reactions

Changes in the microstructure of oil-in-water microemulsions were identified electrochemically by using ferrocene derivatives, methyl viologen, and ferricyanide as the electroactive probes. Microdroplets as well as the bicontinuous microstructure were detected. This was accomplished by determining diffusion coefficients of the probes. Use of probes of different hydrophobicity/hydrophilicity and charge made it possible to investigate different microenvironments of microemulsions including oil, water, and surfactant/cosurfactant interface. Electrochemical reversibility of the probes was affected by the structure and appeared to reflect the ease of mobility across interphases. Reaction potential (E{sub 1/2}) of the probes depended on the composition of the microemulsion.