Crosslinked microporous membrane with pore compensation for efficient and long-term gas separation

Abstract

Utilizing polymers of intrinsic microporosity (PIMs) to construct microporous membranes with high free volume fraction and surface area is a promising strategy to realize high-performance carbon capture. However, plasticization and physical aging remarkably limits the practical applications of PIM-based membrane separation. This work proposed a pore-compensation crosslinking strategy to fabricate a crosslinked microporous membrane with firmly inter-/intra-chain arrangement and highly-preserved CO2 permeation for efficient and long-term gas separation. Amino-functionalized UiO-66 (UiO-66-NH2) was employed to play the dual-function of crosslinker and pore compensation in the construction of crosslinking network among the bromomethylated PIM (BM-PIM) matrix via multiple covalent-crosslinking reactions. Compared with conventional crosslinking agents, the porous structure of UiO-66-NH2 crosslinkers provided additional gas transport channels for compensating the reduction of free volume during the formation of crosslinking network. Meanwhile, the unsaturated metal sites on UiO-66-NH2 crosslinkers enhanced the CO2 transport. Accordingly, the crosslinked microporous membrane with pore compensation achieved an excellent gas separation (CO2/N2 and CO2/CH4 separation factors of 32.2 and 49.3) and structural stability with superior anti-plasticization (plasticizing pressure up to 0.8 MPa) and anti-aging (CO2 permeability loss <15 % after 180 days). The pore-compensation crosslinking strategy offers a novel method to fabricate high-performance microporous membrane for efficient carbon capture.