title: Multilayered poly(vinylidene fluoride) composite membranes with improved interfacial compatibility: correlating pervaporation performance with free volume properties.
abstract: A spin-coating process integrated with an ozone-induced graft polymerization technique was applied in this study. The purpose was to improve the poor interfacial compatibility between a selective layer of poly(2-hydroxyethyl methacrylate) (PHEMA) and the surface of a poly(vinylidene fluoride) (PVDF) substrate. The composite membranes thus fabricated were tested for their pervaporation performance in dehydrating an ethyl acetate/water mixture. Furthermore, the composite membranes were characterized by field emission scanning electron microscopy (FE-SEM) for morphological change observation and by Fourier transform infrared spectroscopy equipped with attenuated total reflectance (ATR-FTIR) for surface chemical composition analysis. Effects of grafting density and spin-coating speed on pervaporation performance were examined. The composite membrane pervaporation performance was elucidated by means of free volume and depth profile data obtained with the use of a variable monoenergy slow positron beam (VMSPB). Results indicated that a smaller free volume was correlated with a higher pervaporation performance of a composite membrane consisting of a selective layer of spin-coated PHEMA on a PHEMA-grafted PVDF substrate (S-PHEMA/PHEMA-g-PVDF). The composite membrane depth profile illustrated that an S-PHEMA layer spin-coated at a higher revolutions per minute (rpm) was thinner and denser than that at a lower rpm.
authors: R&D Center for Membrane Technology, Department of Chemical Engineering, Chung Yuan University, Chung-Li 32023, Taiwan.
authors: Quanfu
authors: Q
authors: An
authors: Jung-Tsai
authors: JT
authors: Chen
authors: Manuel
authors: M
authors: De Guzman
authors: Wei-Song
authors: WS
authors: Hung
authors: Kueir-Rarn
authors: KR
authors: Lee
authors: Juin-Yih
authors: JY
authors: Lai
mesh_terms: D008567:Membranes, Artificial; D010126:Ozone / Q000737:chemistry; D010316:Particle Size; D058105:Polymerization; D011145:Polyvinyls / Q000737:chemistry*; D013499:Surface Properties; D014835:Volatilization; D005465:Fluorocarbon Polymers
chemical_list: D008567:Membranes, Artificial; D010126:Ozone; D011145:Polyvinyls; C024865:polyvinylidene fluoride; D005465:Fluorocarbon Polymers