Novel Ultrathin Membranes Composed of Organic Ions

Until recently, construction of bilayers was an exclusive mission of nature. It requires careful choice of compounds, whose delicate interplay between head group attraction and chain repulsion engenders a truly unique balance over a narrow temperature range. We report the investigation of artificial bilayers composed of long-chained organic ions, such as dodecyltrimethylammonium (DMA(+)) and perfluorooctaonate (PFO-). Various ratios of DMA/PFO surfactants result in bilayers of different stability, thickness, area per molecule, and density profiles. In our quest for water filtration, we incorporated aquaporin protein into the DMA/PFO bilayer but did not observe sufficient stability of the system. We discuss further steps to utilize these surfactant bilayers as highly selective, salt-impermeable membranes.