| Abstract
| - Mechanistic studies were conducted on UV-assisted graft polymerization of N-vinyl-2-pyrrolidinone (NVP) onto poly(ether sulfone) (PES) ultrafiltration (UF) membranes using adip process. The molecular weight cutoff (MWCO) values of the UF membranes were 50,70, and 100 kDa and the range of NVP monomer concentrations was 2−10 wt %. Ourstandard photooxidation protocol with 300-nm lamps was used. By operating below anirradiation energy, E< 4 kJ/m2, both homopolymerization and main-chain scission can beminimized with up to CNVP = 5 wt % NVP concentration for all three UF membranes. Auniversal linear plot of the net amount grafted versus monomer concentration timesirradiation energy (CNVP × E) for E< 4 kJ/m2 was obtained for four NVP concentrationsand three membranes. Resulting from graft polymerization, there appears to be a qualitativerelationship between the thickness of the dense skin layer and the membrane surfaceroughness as measured by atomic force microscopy. Post-modification washing with ethanolwas able to effectively remove entrapped homopolymer and other fragments. Also, UV-assisted graft polymerization of NVP on PES UF membranes effectively reduced irreversiblemembrane fouling. A protocol for optimizing graft-assisted photopolymerization of PES UFmembranes is provided.
- Three critical aspects of graft-induced photooxidative polymerization of N-vinyl-2-pyrrolidone (2−10 wt %) on poly(ether sulfone) membranes (50, 70, and 100 kDa molecular weight cutoffs) for optimizing ultrafiltration performance with protein solutions are addressed, including modification conditions, choice of membrane structure, and evaluation of washing conditions after modification.
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