Electropolymerized thin films with a microporous architecture enabling molecular sieving in harsh organic solvents under high temperature

Abstract

Engineering membranes for precise molecular sieving in harsh organic solvents offer unprecedented opportunities for widening the application of organic solvent nanofiltration (OSN). Here, we introduce tris(4-carbazoyl-9-ylphenyl)amine (TCTA) as the monomer to form robust conjugated microporous polymer (CMP) membranes via electrochemical polymerization for OSN in a challenging environment. The method enables the use of rigid CMP membranes in harsh dimethylformamide (DMF) with temperature up to 100 °C. The resulting membranes show size-dependent selectivity towards charged dyes and pharmaceutical molecules. Moreover, the membranes present excellent stability in DMF solution containing a high base content of triethylamine at different temperatures due to their rigid crosslinked chemical structure. The optimal membrane can reach 94.4 ± 2.2% rejection of Allura Red AC (496.42 g mol⁻¹) at a dimethylformamide (DMF) permeance of 33.1 ± 1.2 L m⁻² h⁻¹ bar⁻¹ at 100 °C. To the best of our knowledge, this is the first report to experimentally recognize the unique advantages of CMPs in high-temperature OSN applications.