Grafting Polymer Brushes From Poly (Vinylidene Fluoride) Surface And Physicochemical Properties

In recent years, poly(vinylidene fluoride) (PVDF) has received much attention because of its well-known physical and chemical properties, such as high-temperature stability, excellent chemical resistance, low water sorption and low dielectric constant, and so on. PVDF has been widely used for biomedical and other advanced technological applications. Just like the other dielectric polymers, its characteristic low surface energy and resulting strong adsorption of proteins and low biocompatibility have created numerous technical challengers. In this connection, amount of researches have been devoted to the surface modification of PVDF.Firstly, in my thesis, controlled grafting of well-defined polymer brushes on the poly(vinylidene fluoride) (PVDF) films was carried out by the combination of chemical treatment and surface-initiated atom transfer radical polymerization (ATRP). Surface-initiators were immobilized on the PVDF surfaces by surface hydroxyl functionalization and esterification of the hydroxyl groups covalently linked to the surface with 2-bromoisobutyrate bromide. Homopolymer brushes of methyl methacrylate (MMA) and poly(ethylene glycol) methyl ether methacrylate (PEGMA) were prepared by surface-initiated ATRP from the α-bromoester functionalized PVDF surface. The chemical composition of the graft-functionalized PVDF surfaces was characterized by X-ray photoelectron spectroscopy (XPS) and attenuated total reflectance (ATR) FT-IR spectroscopy. Kinetics study revealed a linear increase in the graft concentration of poly(methyl methacrylate)(PMMA) and poly(poly(ethylene glycol) methyl ether methacrylate)(PPEGMA) with the reaction time, indicating that the chain growth from the surface was consistence with a "controlled" or "living" process. The "living" chain ends were used as the macroinitiator for the synthesis of diblock copolymer brushes. Water contact angles on PVDF films were reduced by surface grafting of PPEGMA and PMMA.Well-defined comb copolymer brushes from PVDF surface was also carried out. Surface initiators were generated on the PVDF surface by hydroxyl functionalization via chemical treatment, followed by 2-bromoisobutyration of hydroxyl groups.