(637b) Versatile Strategy for the Combinatorial Design and Fabrication of Thin Film Composite Membranes

Conventional thermal separations of aqueous solvent mixtures are energy intensive and costly. Aqueous polar solvent mixtures often present the challenge of azeotrope formation, requiring additional operations for separation. Membrane-based separations have emerged as an energy- and cost-efficient alternative separation method, with pervaporation as the prime candidate for separating these mixtures. Current polymeric pervaporation membranes are limited to a few commodity polymers that are often not molecularly designed for the intended separation, leading to low fluxes and mild selectivity. In addition, synthesizing these polymers and fabricating the membranes requires several liters of volatile organic solvent per gram of polymer deposited. This project combines polymer synthesis and deposition into one step to rapidly produce thin polymer films with a wide variety of compositions through a process we term spin-coating ring-opening metathesis polymerization (scROMP). The scROMP approach allows for thin polymer films to be fabricated in under three minutes on coupon-sized supports using cyclic olefin monomers, Grubbs 3^rd generation catalyst, and as little as half a mL of solvent per 25 cm² of polymer selective layer. Polymers fabricated through scROMP were characterized by ATR-FTIR, stylus profilometry, SEM, contact angles, and GPC to determine properties as scROMP parameters and monomers were varied. The monomer norbornene diacyl chloride (NBDAC) has been utilized in scROMP on poly(acrylonitrile) supports to form pNBDAC thin film composite membranes (TFC). The acyl chloride functionality present in pNBDAC enables the TFC to be easily modified with a wide array of amines and alcohols after polymerization to fine-tune the polymer properties for the dehydration of specific solvents. The effects of side chain composition, length, and cross-linking density were correlated to TFC membrane performance in the dehydration of ethanol. The scROMP method is being paired with a screening workflow based on molecular dynamics simulations to rapidly sample the wide array of potential compositions and accelerate the discovery of new polymer membrane selective layers.