Rigid-flexible coupled organosilica membranes toward high-efficiency molecules separation

Membrane-based technology has garnered significant interest in the separation and purification of molecules due to its inherent advantages, such as high efficiency, low energy consumption, and ease of operation. In this study, rigid-flexible coupled organosilica membranes were fabricated through co-polymerization using 1,2-bis(triethoxysilyl)acetylene (BTESA) containing rigid acetylene bridges and 1,2-bis(triethoxysilyl)propane (BTESP) containing flexible propane bridges. The incorporation of flexible propane bridges into BTESA networks allowed for precise adjustment of the network structures, resulting in composite BTESA-P membranes with improved molecular sieving properties. BTESA-P membrane demonstrated significant promise for applications in both CO₂ capture and pervaporation (PV) dehydration due to its high potential. BTESA-P30 membrane, fabricated using the rigid-flexible coupled strategy, demonstrated a CO₂ permeance of 3807 GPU and a CO₂/N₂ selectivity of approximately 40. These results surpassed those of numerous previously reported membranes, indicating significant potential for CO₂ capture applications. BTESA-P30 membrane exhibited significant competitiveness in the decarbonization process of natural gas. More significantly, analogous occurrences are evident in gas permeation and PV separation process, where the permeation mechanism of gas and PV separation is primarily governed by molecular sieving. The utilization of diverse organosilica precursors in the rigid-flexible coupled strategy proposed in this study offers increased potential for membrane structure design and energy-efficient separation of molecules.