Bicontinuous microemulsions as media for electrochemical studies

Biocontinuous microemulsions of didodecyldimethylammonium bromide (DDAB)/dodecane/water were explored as media for voltammetric reductions and oxidations of ruthenium(III) hexaammine, ferrocyanide, ferrocene, cob(II)alamin, and several polycyclic aromatic hydrocarbons (PAHs). These clear microemulsions are conductive and are believed to contain a dynamic extended network of interconnected water tubules. Agreement of simulated and experimental voltammetric data shows that electrochemical theory for homogeneous media is followed to a good approximation in DDAB microemulsions. Diffusion of electroactive solutes did not reflect the high bulk viscosities of the microemulsions. Non-polar molecules and ions diffuse as if they were in neat oil or aqueous media, respectively, and voltammograms with good signal to noise ratio are obtained. Reductions of PAHs in the microemulsions occurred by an ECE-type pathway, with nearly reversible one-electron reductions achieved at high scan rates.