Preparation of temperature-responsive PPTA/PA@[PNIPAM-PEGMA-PEI] nanofiltration membranes for high-temperature separation

Controllable design of ternary PNIPAM-PEGMA-PEI microgel with enhanced hydrophilicity and covalent anchoring • Direct embedding of microgels into polyamide Layer via interfacial polymerization • Long-Term anti-scaling performance with thermally triggered self-cleaning and permeance enhancement As a cutting-edge intelligent membrane material, temperature-responsive composite membranes can reversibly regulate the surface properties and pore size structure of the membrane according to changes in ambient temperature, demonstrating unique application potential in the field of high-temperature separation. In this study, we used fully rigid aromatic poly ( p -phenylene terephthamide) (PPTA) as the porous base membrane and designed a temperature-resistant macromolecule. By introducing hydrophilic poly(ethylene glycol) methacrylate (PEGMA) monomers into the PNIPAM-PEI system, we synthesized the PNIPAM-PEGMA-PEI ternary copolymer microgel, and directly embedded it into the surface separation layer of positively charged polyamide using interfacial polymerization to obtain high-temperature resistant PPTA/PA@[PNIPAM-PEGMA-PEI] nanofiltration membranes, achieving significant reduction in membrane surface contamination rates while maintaining temperature-sensitive regulation of membrane pore size. The membrane exhibited a 57.9% increase in pure water flux at 60 °C and achieved salt rejections above 97% for Na 2 SO 4 , CaCl 2 , and MgSO 4 (5 g/L) at 25 °C. During a 180 h test with periodic thermal transitions, permeance rose from 9.8 to 16.4 L·m −2 ·h −1 ·MPa −1 while retention remained above 89%. This heat-triggered cleaning and reversible pore-size regulation originate from the reversible chain collapse of PNIPAM above its LCST, providing a new strategy for designing highly permeable, regenerable, and anti-scaling nanofiltration membranes for high-temperature desalination and high-salinity wastewater treatment.