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.