Molecular design and fabrication of PIM-1/polyphosphazene blend membranes with high performance for CO2/N2 separation

New polymeric blend membranes for CO2 separation were synthesized based on insights from molecular dynamics simulation. A molecular-level structure-property relationship in polymers of intrinsic microporosity (PIM) based blend membranes was investigated in detail computationally. Calculated local density profiles and energy of interaction of the blend membranes, composed of PIM-1 and various polyphosphazenes, showed that using the polyphosphazene with a higher concentration of ether side chains can improve the compatibility with PIM-1. Based on the findings of computational studies, blend membranes were experimentally fabricated from PIM-1 and polyphosphazenes with various polyether side chain concentrations. Polyether concentration in polyphosphazenes was correlated with the film properties and gas transport performance of the blend membranes. Blend membranes showed very high CO2 permeability (3100-5300barrer) and improved CO2/N2 selectivity (24–28), outperforming all other PIM-based blend membranes reported to date. Moreover, the CO2 permeability performance of the blend membranes was tested 566 h under real post-combustion flue gas from a coal-fired power plant, including CO2, N2, H2O, O2, SOx and NOx.