(519c) Transforming Barrier Polymers to High-Performance Gas Separation Membranes

Polymer membranes have excellent scalability and good separation performance for many gas pairs. However, owing to their permeability-selectivity tradeoff, their large-scale gas separation application has yet to evolve beyond air separation and natural gas purification. Carbon molecular sieve (CMS) membranes are derived by controlled pyrolysis of polymer membranes to provide a good balance of permeability, selectivity, and scalability. Formation of CMS membranes often relies on pyrolysis of advanced and expensive polymer precursors, such as polymers of intrinsic microporosity and fluorinated polyimides. Barrier polymers are much less expensive and used for beverage packaging at large scale. Barrier polymers, however, have been rarely considered for membrane-based gas separations due to their ultra-low gas permeabilities.

In this talk, we will present the transformation of impermeable barrier polymers to high-performance CMS membranes. An aromatic barrier polymer precursor was synthesized by condensation polymerization, which showed ultra-low CO₂ permeability (<0.002 Barrer) at room temperature. Pyrolysis of the barrier polymer precursor provided a novel CMS membrane that had over 100,000 times higher CO₂ permeability than the barrier polymer precursor. The barrier polymer-derived CMS membrane showed attractive selectivities, which put them above the polymer upper bounds for several commercially important gas pairs.