Irradiation-induced grafting of poly(vinylidene fluoride)-graft- poly(styrene sulfonic acid) for the preparation of planar and tube-shaped air-drying membranes

摘要

A novel air-drying membrane was developed and investigated as an alternative for planar and tube-shaped drying membranes composed of Nafion ~?. The new membrane is based on poly(vinylidene fluoride) (PVDF) polymer types grafted with polystyrene sulfonic acid. Modification of the PVDF membrane by chemical grafting was initiated via γ-irradiation of pre-made film and tube-shaped samples. The grafting was conducted while the pre-irradiated PVDF samples were immersed in styrene monomer solution. Three unique characterization methods were introduced to evaluate the ion exchange and barrier functions of the membrane. This investigation focuses on optimizing the degree of grafting yield, and subsequently the control of the membrane's overall functional performances, through (1) monitoring the PVDF's degree of crystallinity and (2) monitoring the styrene monomer solution temperature, respectively. Different levels of crystallinity were achieved by melt blending the PVDF-copolymer with PVDF-homopolymer, in various mixing ratios. Another variable examined in this investigation was the introduction of an ionic complex on the sulfonic acid end groups, and its effect on the membrane functional performance was studied.