Reactive substrate-driven interfacial polymerization for wrinkled polyamide membranes with enhanced permeance

A novel strategy was developed to regulate polyamide (PA) membrane morphology and performance by introducing a reactive copolymer, poly(styrene-alt-maleic anhydride) (PSMA), into the polyethersulfone (PES) substrate. The reactive anhydride groups of PSMA first react with piperazine (PIP) monomers, subsequently affecting diffusion and reaction dynamics of the remaining monomers during interfacial polymerization (IP) for PA layer formation. As a result, wrinkled PA morphologies were formed, enhancing the surface roughness and effective filtration area. The wrinkled PA membranes exhibited significantly improved water permeance (up to 19.7 L m^-2 h^-1 bar^-1) while maintaining comparable rejection rates of 98.7 %, 98.2 %, 85.7 %, 6.1 %, 7.1 % for Na₂SO₄, MgSO₄, MgCl₂, LiCl, and NaCl, respectively, due to the similar free volume to unmodified membranes. This work offers a promising approach to tailor membrane structure and optimize nanofiltration performance via substrate reactivity engineering.