Enhanced CO2 selectivities by incorporating CO2-philic PEG-POSS into polymers of intrinsic microporosity membrane

The urgent demand of capturing CO2 from energy relevant applications stimulated researchers to develop novel high-performance membrane materials. PIM-1, a representative class of polymers of intrinsic microporosity (PIMs), possesses high permeability but low selectivity due to its highly twisted ladder-like structure. A facile approach to improve CO2 separation performance of PIM-1 is to implant CO2-philic fillers. In this study, a novel nano-sized filler Poly(ethylene glycol) functionalized Polyhedral oligomeric (PEG-POSS), with PEG anchored on POSS was incorporated into PIM-1 membrane at nanoscale level to increment CO2 selectivities of the membrane. The as-prepared PIM-1/PEG-POSS mixed matrix membranes (MMMs) were characterized by Fourier transform infrared (FT-IR) spectra, thermal gravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Single gas permeabilities of N2, CH4 and CO2 were measured by the time-lag method. PIM-1/PEG-POSS membranes showed enhanced CO2 selectivity over CH4 and N2 at high PEG-POSS loadings. Specifically, the PIM-1/PEG-POSS membrane with 10 wt% PEG-POSS nanoparticles exhibited the optimal separation performance, of which the CO2 permeability reached 1300 Barrer and CO2/CH4 selectivity increased by 150% compared with the pristine PIM-1, which surpassed the 2008 Robeson upper bound. The as-prepared PIM-1/PEG-POSS MMMs show great potential for CO2 capture.