The Hydrophilic Modification Study Of The Polyvinylidene Fluoride

Polyvinylidene fluoride (PVDF) has good chemical stability, thermal stability and mechanical strength, and is mainly used to prepare separation membranes. But the application of PVDF membrane was limited because PVDF membrane is hydrophobic and vulnerable to fouling. Therefore the hydrophilicity of PVDF is particularly important.3-(methacryloylamino) propyl-dimethyl(3-sulfopropyl)-ammonium hydroxide (MPDSAH) is a typical zwitterionic monomer, which contains hydrophilic and anti-pollution groups, and can be used for modification of hydrophobic materials. In this paper, in order to modify PVDF membrane, MPDSAH was grafted by Ultraviolet light. PVDF solution was pretreated by Ozone, and then MPDSAH was grafted onto it. Thus the hydrophilicity and the anti-fouling property of PVDF membrane were improved simultaneously.First of all, using benzophenone (BP) as photosensitizer, MPDSAH was grafted onto the surface of the PVDF membrane by UV irradiation. In order to optimize the reaction conditions, the effect of the intensity of UV lamps, and the effect of the concentration of MPDSAH and BP solutions were discussed. The results showed that MPDSAH was successfully grafted on the surface of the membrane. After modification, the contact angle of the PVDF membrane can reduced from 118°to 43°.The adsorption of BSA can reduced from 13mg/cm2·g to 3mg/cm2·g.In addition, MPDSAH was grafted onto ozone-pretreated PVDF chains. Then the PVDF membranes were prepared by phase inversion method. The effect of grafting MPDSAH on membrane structure and the effect of monomer-polymer ratio on membrane's hydrophilicity were discussed.The results showed that PVDF membranes can be modified by UV, to form hydrophilic membranes. UV grafting is high in efficiency, low in cost and can be industrialized. PVDF solution pretreated by ozone, and then grafted with MPDSAH could also be used to prepare hydrophilic PVDF membranes.