Scalable Pillar[5]arene-Integrated Poly(arylate-amide) Molecular Sieve Membranes to Separate Light Gases

Abstract

Molecular sieve membranes and their analogues could potentially transform energy-intensive gas separation processes. However, many such membranes suffer from either limited process ability or physical stability including plasticization of semi-flexible microstructures. Here, we report on a new variation of all-polymer-based molecular sieve membranes that could tackle these specific challenges. These membranes were prepared by the interfacial polymerization of pillar[5]arene, m-phenylenediamine, and trimesoyl chloride to create characteristic poly(arylate-amide) heteropolymer microstructures. Pillar[S]arenes were crosslinked into the films with net weight fractions of up to similar to 47%, wherein the, 4.7 angstrom cavities of pillar[5]arenes were interconnected with similar to 2.8 angstrom apertures. These microstructures provided preferred permeation paths for smaller molecules (He and H-2) among the tested light gases (He, H-2, CO2, O-2, N-2, and CH4) and resulted in significant molecular sieving effects with representative pure gas selectivities of 32 (H-2/CO2), 150 (CO2/CH4), 4600 (H-2/CH4), 13 (O-2/N-2), and 4.7 (N-2/CH4) at 35 degrees C and 10 atm. These separation factors outperform most polymer-based gas separation membranes, while providing membrane features such as thin film barriers, cross-linked polymer backbones, and excellent processability resulting from interfacial polymerization that are critical for large-scale operations.