Intermediate thermal manipulation of polymers of intrinsic microporous (PIMs) membranes for gas separations

Abstract The high fractional free volume (FFV) endowed polymers of intrinsic microporosity (PIMs) with high gas permeability but low selectivity. Herein, an intermediate temperature range was deliberately utilized to tune PIM‐1 membrane microstructure in nitrogen atmosphere to enhance gas separation performance. During intermediate thermal manipulation, the synergistic effects of thermal‐induced cross‐linking and decomposition on PIM‐1 membranes have optimized the micropores for significantly increasing membrane molecular‐sieving ability with the boosted selectivity of 350 (H 2 /N 2 ), 1,472 (H 2 /CH 4 ), 3,774 (H 2 /C 3 H 8 ), and 197 (CO 2 /CH 4 ) respectively, with the H 2 permeability of 234 Barrer, correspondingly, surpassing the “Robeson's Upper Bound”. The facile strategy simultaneously utilizing the thermal‐induced cross‐linking and decomposition, might provide a new platform to develop the high‐performance membranes for highly‐efficient hydrogen purification and CO 2 separations.