(410b) Amphiphilic Polyelectrolyte Complexes As High Flux, Highly Selective, Fouling-Resistant Membrane Selective Layers

Membranes offer a highly energy-efficient, simple to operate, scalable and portable separation method for many applications, from water treatment to oil and gas processing to pharmaceutical manufacturing. Yet, their broader use is often limited by insufficient selectivity and/or fouling with complex feeds. Self-assembling copolymers have led to the formation of some of the best-performing membranes in the literature, particularly in terms of fouling resistance and selectivity control. This project describes a new family of self-assembling polymer selective layers: amphiphilic polyelectrolyte complexes (APECs), prepared by coating consecutive layers of two amphiphilic polyelectrolytes (APEs). APEs are water-insoluble copolymers combining a hydrophobic monomer (e.g. trifluoroethyl methacrylate, TFEMA) with either an anionic monomer (e.g. sulfopropyl methacrylate, SEMA) or a cationic monomer (e.g. trimethylaminoethyl methacrylate, TMAEMA). To prepare APEC membranes, a porous support is first bar-coated by the first APE (e.g. a copolymer of TFEMA and SEMA) in an alcohol. Upon solvent evaporation, a layer of the oppositely-charged APE (e.g. a copolymer of TFEMA and TMAEMA) is bar coated on top, again from alcohol. APEC membranes exhibit much smaller effective pore sizes than that obtained from either APE as a selective layer, combined with exceptional permeance. For instance, some APEC membranes exhibit permeances of 20 liters/m².bar with molecular weight cutoffs below 500 Da. The effective pore size and salt selectivity of APEC membranes can be tuned by changing the charged monomer chemistry and the hydrophobic/charged monomer ratios. APEC membranes also exhibit excellent resistance to fouling by oil emulsions. This demonstrates a versatile and highly customizable approach for developing novel high-performance membranes.