Synthesis of a Poly(methyl methacrylate)-b-Poly[2-(N,N-dimethylamino) ethyl methacrylate] Block Copolymer and Its Effects on the Surface Charges and pH-Responsive Properties of Poly(vinylidene fluoride) Blend Membranes

摘要

A poly(methyl methacrylate) (PMMA)-b-poly[2-(N,N-dimethylamino) ethyl methacrylate] (PDMAEMA) block copolymer was successfully synthesized by a reversible addition–fragmentation chain-transfer method. The resulting copolymer was used to prepare poly(vinylidene fluoride) blend membranes via a phase-inversion technique. The polymorphism, structure, and properties of the blend membranes were investigated by Fourier transform infrared spectrometry, scanning electron microscopy (SEM), ζ potential analysis, and filtration. The results indicate that PMMA-b-PDMAEMA could migrate onto the surface of the membrane during the coagulation process, and more of the β-crystal phase appeared with the increase of the block copolymer in the membranes. The surface morphology and cross section of the membranes were also affected by the copolymer, as shown by SEM. The ζ-potential results show that the surface charges of the membrane could be changed from positive to negative at an isoelectric point as the pH increased. The blend membrane also exhibited good pH sensitivity, and its water flux showed a great dependence on pH. The filtration experiment also indicated that the blend membrane had good hydrophilicity and antifouling properties.