(611b) Ionic Liquid-Modified Block Copolymer Microstructures with Tunable Domain Sizes for Wastewater Treatment and Ion Exchange Membranes

Wastewater is now contaminated with oil, particulates, metals, and other organic compounds due to the rapid rise in oil and gas, petrochemical, pharmaceutical, and food processing industries. Membranes present an easy and energy-efficient solution for removing particulates and oily matter from wastewater. Here we present a methodology to rapidly order block copolymer thin films with well-defined through-thickness channels having low tortuosity. The technique involves blending an ionic additive into the block copolymer solution made from a binary mixture of solvents. This additive acts as a plasticizer in addition to preferentially interacting and segregating into one block of the diblock copolymer. Owing to this plasticization and selective interaction, the films are fully ordered in the casting step. With careful selection of the casting environment that neutralizes surface interactions, we can obtain completely perpendicular domain morphologies with swollen domains and variable domain sizes. This perpendicular microstructure is an excellent candidate for ion conduction membranes. Alternatively, these films can be supported by commercial membranes like poly-ether-sulfone (PES), treated to selectively crosslink one and etch the other block to open the pores and serve as porous filtration membranes. The microstructure can be further altered by changing the solvent components to cast a film with a micellar structure. These micellar films, when annealed, assemble into non-equilibrium asymmetric structures that have a high potential for ion conduction membranes. The film microstructures are characterized via atomic force microscopy, x-ray scattering, and neutron reflectivity. At the same time, the membrane performance is tested using a dead-end cell and UV-vis spectroscopy for wastewater filtration and electrochemical impedance spectroscopy for ion conduction.