Tuning the microstructure of organosilica membranes with improved gas permselectivity via the co-polymerization of 1,2-bis(triethoxysilyl)ethane and 1,2-bis(triethoxysilyl)methane

1,2-bis(triethoxysilyl)ethane (BTESE)-derived membranes have proven thermal and hydrothermal stability and molecular sieving properties. However, BTESE-derived membranes still have low gas permselectivity due to their loose structure. Herein, we propose a novel strategy of co-polymerization using precursors of both BTESE and 1,2-bis(triethoxysilyl)methane (BTESM) to improve the gas permselectivity of BTESE-derived membranes. BTESM is introduced into BTESE network and the microstructure can be adjusted by different molar ratios of BTESE to BTESM. We find that, as the content of BTESM increase, H₂ permeations of BTESE-BTESM membranes remain nearly constant, while the permeations of larger gases (CO₂ and N₂ etc.) exhibit a greatly decreased. The membrane with a molar ratio of BTESE:BTESM = 3:7 exhibits the highest H₂/CO₂ (11.3) and H₂/N₂ (26.8) permselectivity while having a relatively high H₂ permeance (1.52 × 10⁻⁶ mol m² s⁻¹⋅Pa⁻¹). Our findings may provide novel insights into preparation of co-polymerization organosilica membranes with excellent H₂/CO₂ and H₂/N₂ separation performance.