Oriented Monolayer Assemblies to Modify Fouling Propensities of Membranes

摘要

Research was conducted to test whether oriented monomolecular-layer assemblies bearing positive charges would mitigate the fouling propensities of anion-exchange membranes, especially if the oriented layers were fluorinated. Fouling tests with membranes coated by oppositely and similarly charged multilayers should also demonstrate the relative importance of several membrane surface characteristics earlier shown to play roles in initiation of autocatalytic concentration polarization and fouling. Membrane surfaces were modified by coating with individually-oriented layers of amphiphilic modules (having polar and non-polar ends), using the classical Blodgett dipping technique. It was determined that, with appropriate selection of amphiphilic compounds and packing densities, it was possible to independently vary hydrophilicity, homogeneity, and rugosity, thereby establishing the relative importance of these factors in the fouling process. Even a single deposited oriented monolayer of 20A thickness strikingly modified the microscopic appearance and the electrical and fouling behaviors of anion-exchange membranes.