Molecular layer deposition of flexible conjugated microporous polymers on nanofiltration substrates for molecular discrimination in organic solvents

Conjugated microporous polymers (CMPs), characterized by permanent microporosity and exceptional stability, represent a promising class of materials for next-generation molecular-sieving membranes. Nevertheless, high-quality CMP membranes with well-designed pore architectures remain inaccessible due to the challenges associated with processing these materials. Herein, we report a molecular layer deposition (MLD) process for the sequential assembly of 3-butylthiophene and 3,3′-bithiophene in situ on commercial nanofiltration substrates under MoCl 5 oxidation. The precise MLD strategy enables the integration of flexible alkyl chains to soften the CMP backbone while preserving its intrinsic microporosity. The resulting composite CMP membranes enabled high-resolution purification of nanoscale species with molecular weights as low as 270 g mol −1 while exhibiting exceptional long-term stability during continuous operation over 150 h. We also proved that thus-prepared CMP membranes exhibit great potential for the purification and recovery of high-value pharmaceuticals and catalysts. This work highlights the potential of MLD as a versatile strategy for fabricating CMP membranes and grafting internal functionalities, enabling high-resolution separation in liquid systems.