Polyamide membranes with rigid twisted tetraamine monomers for efficient organic solvent nanofiltration

Abstract

Polyamide membranes with rigid twisted structures show excellent permeance and rejection in the field of organic solvent nanofiltration (OSN). However, challenges such as low reactivity, complex synthesis procedures, and high costs persist for certain rigid and twisted monomers, posing obstacles in their synthesis or application processes. To address these challenges, we adopt a low-cost rigid and twisted tetraamine monomer, N,N,N’,N’-tetrakis(4-aminophenyl)-1,4-benzenediamine (TK), for the preparation of polyamide OSN membranes through interfacial polymerization with various acyl chlorides. TK is effectively introduced into the polyamide chain, which involves not only the reactivity of monomers, but also the influence of monomer angle configuration on the formation of chain segments, forming different rigid networks and enabling the active layer to have excellent stability and high porosity. Consequently, the rigid twisted polyamide OSN membranes exhibit a methanol permeance of 13.8 L m^-2 h^-1 bar^-1 and a molecular weight cut-off (MWCO) of 266 Da, outperforming many reported membranes. This work highlights the use of TK as a promising, cost-effective monomer to engineer high-performance OSN membranes with tailored structural features, offering a practical solution for enhanced organic solvent separation processes.