(386d) Tuning Pore Size and Robustness of Membranes Formed By Scalable Self-Assembly of Random Copolymer Micelles

Membrane separations are energy-efficient, simple, and scalable. Yet, their broader use is limited by the separation capabilities of membranes prepared by conventional methods, typically confined to size-based separations. Self-assembly of functional polymeric materials is a powerful method for designing membranes capable of new separations, including the separation of organic compounds of similar size from each other. This can potentially be achieved by membranes that mimic biological pores such as porins, with pores that are only slightly larger than the target solute and functionalized with groups that selectively interact with one compound over another. Our group has developed a method for preparing such membranes by the spontaneous self-assembly of random amphiphilic copolymer in methanol into micelles that are then coated onto a support to form a selective layer of tightly packed micelles. These membranes, produced by a simple manufacturing process, have 1-4 nm pores lined with carboxylic acid groups that enable charge-based separation of organic solutes. Additionally, the carboxylic acid groups can be converted to a wide range of possible functional groups through coupling reactions. This can provide selectivity towards solutes by affinity. Because of the distinctive geometry and selectivity of these membranes, it is valuable to assess the versatility of this technology. The goal of this study was to tune the pore size and increase the robustness of these thin film composite membranes. The pore size was tuned by changing the composition of the copolymer and also by changing the casting solvent, while the robustness of the system was altered by different crosslinking procedures.