Two-stage polymerization towards C–C bonded Conjugated microporous polymer membranes with excellent nanofiltration performance

Abstract

C–C bonded conjugated microporous polymer (CMP) membranes are promising candidates for organic solvent nanofiltration (OSN), in which molecular-sieving selectivity, high permeability, and chemical/structural stability can be integrated. However, it is a big challenge to fabricate CMP membranes by simple coating due to the insolubility and poor processability of CMPs. In this work, three C–C bonded CMP membranes were fabricated by a two-stage polymerization strategy via cyclotrimerization of acetyls. Firstly, the viscous prepolymer solution was coated on a glass plate. After thermal curing based on cyclotrimerization, three C–C bonded CMP membranes were synthesized. Thanks to the aromatic nature of the backbone, high surface area, and narrowly distributed pore sizes, these membranes exhibited high permeability and sharp selectivity for OSN. Especially, even though they have a thickness up to μm-scale, their permeability is still fast, which breaks the stereotype that the ultra-thin property was necessary for fast permeance. The extraordinary stability integrated with excellent permeability and selectivity renders these C–C bonded CMP membranes promising candidates for real-world OSN applications. Besides, this work may be extended to prepare CMP membranes for other applications. • A simple two-stage polymerization[1] was developed to create CCMP membranes with prepolymer as the coating material. • The membrane was fabricated by cyclotrimerization of acetyl groups under mild and atmosphere conditions. • The CCMP membrane exhibited fast solvent permeance, high Young's modulus and large solute retention. • This work solved the paradox between the membrane thickness and the membrane flux.