Synthesis Of Well-defined Amphiphilic Block Copolymers By AGET ATRP And The Hydrophilic Modification To PVDF Membrane

Poly(vinylidene fluoride) is one of the most popular materials with excellent characteristics for microporous membranes, which are widely used in microfiltration and ultrafiltration. However, high driving force, as well as the nonspecific protein adsorption on the membrane surface, is the drawback in the process where PVDF membranes are applied, based on the strong hydrophobility characteristics of PVDF matrix, which often causes serious membrane fouling and thus rapid decline of permeation flux. Thus, it is urgent to find an effective method to improve the hydrophilicity of PVDF membranes. The linear water-soluble polymers are introduced as the additives for hydrophilization into PVDF membranes. However, the traditional technologies are inclined to be washed out of membrane in the procession of the practical application so that a stable hydrophilicity can not be realized.In order to solve this problem, in this dissertation, the linear two block amphiphilic poly was applied to achieve the hydrophilicity modification of poly(vinylidene fluoride) membrane through blending method. A diblock amphiphilic copolymer PMMA-PDMAEMA had been synthesized via activator generated by electron transfer for atom transfer radical polymerization(AGET ATRP). Where methyl methacrylate(MMA) was chosen as the hydrophobic monomer due to its the compatibility of PVDF, while poly[2-(Dimethylamino)ethylmethacrylate](DMAEMA) were hydrophilic monomers.Phase inversion process was adopted to make membranes, and the effects of diblock amphiphilic copolymer on blend membrane were studied, and then hydrophilicity and anti-fouling characteristics of the membrane were characterized.FTIR, 1H-NMR and GPC analyses showed that the synthesized PMMA-Br macroinitiator and PMMA-DMAEMA diblock amphiphilic copolymers had the desired structure. It was found that the PDI of the synthesized diblock copolymers were 1.41(PDI<1.5). The FT-IR and 1H-NMR characterization showed that the successful synthesis of the diblock amphiphilic copolymers via AGET ATRP polymerization route.Compared with pristine PVDF membrane, water contact angles of the blend membranes had decreased greatly(from 97° reduced to about 65°). The water flux of the blend membranes measured under 0.3MPa were considerable improved to120 L·m-2·h-1, while that of the pristine PVDF membrane was 0 L·m-2·h-1. The surface image and cross section of composite membrane were observed by using SEM. SEM images indicated that the pore porosity and diameter had remarkably increased for the PVDF membrane as the addition of amphiphilic copolymers. In the BSA experiment, after being fouled, the adsorption amount of BSA of modified membrane was lower than unmodified membrane averagely by 20%.The results of this thesis had proved that when the diblock amphiphilic copolymer PMMA-DMAEMA, was blended into PVDF membranes, it would influence the structure of the membranes and improve the hydrophilicity and anti-fouling characteristics of the blend membrane. It could be concluded that PMMA-DMAEMA contribute the potential materials to prepare high performance PVDF porous membrane with stable, perfect hydrophilicity.