Spatiotemporal Pattern Formation in Reactive Microemulsions

Irv Epstein, Department of Chemistry, Brandeis University

I shall discuss pattern formation in a system consisting of the components of the Belousov-Zhabotinsky oscillating chemical reaction dissolved in a reverse microemulsion (ME) composed of oil (octane), water and the surfactant AOT. The ME is structured as nanodroplets of water surrounded by a monolayer of surfactant floating in a sea of oil. The BZ reactants reside in the water droplets, whose size and spacing can be tuned by varying the [water]:[AOT] and [oil]:[water] ratios. By varying the structure of the ME and the chemical composition of the reacting mixture, we can sweep through a wide variety of patterns including Turing patterns, spirals and antispirals, oscillons and spatiotemporal chaos. Several of these patterns have not been observed in simpler aqueous media. Model calculations suggest possible explanations for the enhanced pattern-forming capabilities of such microemulsion systems.