Low-Resistance Transport Pathways in POSS/CPBI Mixed Matrix Membranes for Efficient CO2 Separation.

An amino-functionalized polyhedral oligomeric silsesquioxane (NH₂-POSS) was grafted onto molecular chains of a chlorinated alkane-activated polybenzimidazole (CPBI) matrix to fabricate mixed matrix membranes (MMMs) for highly efficient CO₂/CH₄ separation. The nanocages NH₂-POSS contributed significantly to the improvement of the CO₂ separation performance. The following explanations were given as the primary causes: first, the nanocages NH₂-POSS constructed low-resistance transport pathways for accelerating CO₂ transport in MMMs. Second, the amino groups of NH₂-POSS provided carriers for CO₂, benefiting the improvement of CO₂ selectivity. Moreover, the introduced nanocages NH₂-POSS reduced the face to face packing and strong hydrogen bonding between CPBI molecule chains to enhance CO₂ permeability. As a result, the CO₂/CH₄ separation performance of CPBI/NH₂-POSS MMMs was significantly improved. In particular, compared with the pure CPBI membrane, the CO₂ permeability and CO₂/CH₄ separation factor of CPBI/NH₂-POSS-6 MMM were increased by 196.9 and 248.2%, respectively. This work suggested that an efficient strategy for CO₂/CH₄ separation involved the construction of low-resistance transport pathways by nanocage fillers. [ABSTRACT FROM AUTHOR]