(280a) Rapidly Ordered Block Copolymer Membranes with Tunable Pore Sizes for Wastewater Treatment

The present surface water resources will soon be insufficient to meet the needs of the next generations. One of the solutions is to reuse water after purification. Wastewater is now contaminated with oil and other organic compounds due to the rapid rise in oil & gas, petrochemical, pharmaceutical, and food processing industries. Membranes present an easy and energy-efficient solution for the removal of both particulate and oily matter from wastewater. Here we present a methodology to rapidly order low χ (Flory Huggins interaction parameter) block copolymer (Poly(styrene-b-methyl methacrylate)) thin films with well-defined through-thickness channels having minimal tortuosity. The technique involves solvent casting of asymmetric BCP films from solution mixtures doped with plasticizing additives that selectively segregate into one of the domains of the BCP and modify domain sizes. Owing to the selectivity and plasticization capability of the additive and the preferential solvation of BCP components in the solvent mixture, the film is fully ordered in the casting process. With careful selection of the casting environment, a completely perpendicular domain morphology can be achieved. These films are supported by commercial membranes like PES and treated to selectively crosslink one and etch the other block to open the pores. The tradeoff between size selectivity and permeability can be controlled through additive concentration in the system. Overall, the membranes show high water fluxes due to the lower pore tortuosity. The film microstructure is characterized via atomic force microscopy and x-ray scattering. At the same time, the membrane performance is tested using a dead end and a cross-flow fluid cell and UV-vis spectroscopy.