Microporous membranes comprising conjugated polymers with rigid backbones enable ultrafast organic-solvent nanofiltration

Conventional technology for the purification of organic solvents requires massive energy consumption, and to reduce such expending calls for efficient filtration membranes capable of high retention of large molecular solutes and high permeance for solvents. Herein, we report a surface-initiated polymerization strategy through C–C coupling reactions for preparing conjugated microporous polymer (CMP) membranes. The backbone of the membranes consists of all-rigid conjugated systems and shows high resistance to organic solvents. We show that 42-nm-thick CMP membranes supported on polyacrylonitrile substrates provide excellent retention of solutes and broad-spectrum nanofiltration in both non-polar hexane and polar methanol, the permeance for which reaches 32 and 22 l m−2 h−1 bar−1, respectively. Both experiments and simulations suggest that the performance of CMP membranes originates from substantially open and interconnected voids formed in the highly rigid networks. Membranes with high selectivity and high permeance that allows rapid passage of solvent molecules are desirable for efficient separation processes. Microporous conjugated-polymer membranes have now been fabricated through surface-initiated polymerization. These membranes are capable of ultrafast organic-solvent nanofiltration because of the high porosity and pore interconnectivity originating from the rigid skeleton.