PIM-1/ Matrimid Blend Membranes for Gas Separation

Owing to the cost competitiveness and ease of processing of polymeric membranes, polymers have been widely used as the material for the fabrication of gas separation membranes in both research development and industrial applications. Recently, the polymers of intrinsic microporosity have gained the attention as one of the potential materials for membrane gas separation. The contorted ladder-like structure in polymers of intrinsic microporosity, specifically PIM-1 possesses high permeability but with moderate selectivity for O₂/N₂, CO₂/N₂ and CO₂/CH₄ separation. In this work, we explore the most convenient and time efficient strategy of tuning the permeability and selectivity by blending PIM-1 with different compositions of Matrimid. The polarized light microscope (PLM) analyses evidence that most of the PIM-1/Matrimid blends reveal partially miscible behavior. The incorporation of PIM-1 in Matrimid leads to a significant increase in gas permeability of Matrimid rich membranes with a minimal decrease in gas-pair selectivity. The additions of 5 and 10 wt% PIM-1 into Matrimid induce the permeability increments of 25% and 77%, respectively from the original 9.6 to 12 and 17 Barrer without compromising its CO₂/CH₄ selectivity. For O₂/N₂ separation, the incorporation of a small amount of Matrimid (e.g., 5-30 wt%) into PIM-1 promotes a fair increase in selectivity and drives the overall gas separation performance surpassing or close to the upper bound. At binary gas tests of CO₂/CH₄ (50%/50%), the 30 wt% PIM-1 in Matrimid membrane has a CO₂ permeability of 50 Barrer and a CO₂/CH₄ selectivity of 31.