Polar aprotic solvent-resistant nanofiltration membranes generated by flexible-chain binding interfacial polymerization onto PTFE substrate

The practical application of solvent-resistant nanofiltration (SRNF) still faces major challenges arising from the swelling and dissolution of substrates in organic solvents, especially in polar aprotic solvents such as dimethylformamide (DMF). To address these issues, polytetrafluoroethylene (PTFE) substrates with strong resistance to organic solvents was employed to fabricate solvent-resistant nanofiltration composite membranes. A novel reverse flexible-chain binding interfacial polymerization (rFB-IP) was proposed to fabricate polyamide (PA) selective layer onto PTFE substrate with ultra-low surface energy. Specifically, aiming at strengthening the bonding force between the substrate and selective layer, PDMS was employed as a flexible-chain binder to generate a cross-linked network on the substrate surface and within the pores to generate an interpenetrating structure with PA selective layer. The as-prepared rPA-PDMS/mPTFE composite membrane exhibited DMF permeance of 0.4 L m−2 h−1 bar−1, 97.1% rejection to Rose Bengal (RB), a stable performance during a filtration process for 120 h, or after being immersed in DMF for 120 d. Therefore, the rFB-IP technique successfully settled the issues of the application of PTFE substrate for composite membrane fabrication, and would have outstanding potential in the development of polar aprotic SRNF membrane.