Preparation and Characterization of a High Perm-selectivity Poly(amide/ester)Nanofiltration Membrane Using a Poly(vinylidene fluoride)Substrate

Using polyvinylidene fluoride(PVDF) as a substrate material,an amphiphilic triblock copolymer PHEAA-b-PMMA-b-PHEAA(PHMH)with hydrophilic poly( N-hydroxyethyl acrylamide)(PHEAA) and hydrophobic polymethyl methacrylate(PMMA) chain segments was used as a modifier for fabrication of PVDF/PHMH substrate via non-solvent induced phase separation method. The surface pore size of the PVDF/PHMH substrate was smaller than that of the unmodified PVDF substrate,and the porosity and hydrophilicity were increased. Compared with PVDF substrate nanofiltration membrane (N0),PVDF/PHMH substrate nanofiltration membrane(N1)prepared via interfacial polymerization exhibited a higher surface roughness,hydrophilicity and lower molecular weight cut-off. The N1 membrane showed a rejection of Na2SO4 up to 96.0% and the water permeation flux was 304 L center dot m(-2)center dot h(-1)center dot MPa-1,which exceeded those of commercial nanofiltration membranes.