Structure control of hydrophilized PVDF hollow-fiber membranes using amphiphilic copolymers: PMMA-co-P (HEMA-co-MEA)

Abstract

An amphiphilic copolymer was used in the fabrication of hydrophilized poly (vinylidene fluoride) (PVDF) membranes. The amphiphilic copolymer was synthesized via the catalytic chain transfer radical polymerization (CCTP) of poly (methyl methacrylate) macromonomer (PMMA-MM), 2-hydroxyethyl methacrylate (HEMA), and 2-methoxyethyl acrylate (MEA). The copolymer, PMMA-co-P (HEMA-co-MEA) with various copolymerization ratios of HEMA and MEA was added to a stock solution containing PVDF, poly (vinylpyrrolidone) (PVP) and N,N-Dimethylacetamide (DMAc) in the preparation of hollow-fiber membranes via the non-solvent induction phase separation (NIPS) method. The resultant membrane had various porous structures and hydrophilicity. The permeability of the resultant membrane tended to be higher when a copolymer with a lower HEMA copolymerization ratio was added. The membrane was prepared using a copolymer with a high composition ratio of HEMA and had a structure that featured a smaller pore diameter and less connectivity in the inner surface, which reduced the water permeability. Amphiphilic copolymers would interfere with the formation of membrane structure. On the other hand, the surface hydrophilicity was better than that of a blank PVDF membrane, which revealed an interesting trade-off between hydrophilicity and water permeability.