Thin-Film Composite Membrane Fabrication By Atom Transfer Radical Polymerization

Surface-initiated atom transfer radical polymerization (ATRP) has been used extensively by our group to uniformly coat membrane surfaces with structurally well-defined polymer nanolayers for liquid-phase separations. In this study, we applied this coating strategy to prepare thin-film composite membranes for gas-phase CO₂ separations. We seek to understand how polymer film structure impacts permeance, selectivity, plasticization, and physical aging. Surface-initiated ATRP was used to graft poly(poly(ethylene glycol) monomethyl ether methacylate (PEGMA)-co-glycidyl methacrylate (GMA)) from a support membrane that was pre-coated by a proprietary nonporous gutter layer material. Ether groups of PEGMA enhance CO₂ selectivity, while epoxy groups on GMA provide sites for crosslinking. Parallel efforts on a reflective substrate allowed us to measure polymer nanolayer growth kinetics. Atomic force microscopy was used to assess coating uniformity. Membrane performance was evaluated using CO₂ and N₂ as model gases. Permeance and selectivity were measured before and after crosslinking.