Study On Preparation And Application Of Surface Fluorinated Poly (ethylene-vinyl Acetate) Film

Poly (ethylene-vinyl acetate) (EVA) is a widely used thermoplastic resin. Physical properties of EVA materials mainly depend on the VA content. EVA with the VA content of 20-30 wt.% is of various applications as moldings in different shapes due to their good physical properties, ease of handling and processing. Fluoropolymers are high performance materials with various functional properties including low surface energy and surface tension, low refractive index, exceptional chemical and biological inertness, and enhanced biocompatibility. Introduce of the fluorine-containing groups in EVA side chains confers the material new surface properties. Intense effort has been made on the modification of EVA materials, however, none of them associated with flurination, especially with surface flurination via grafting.In this study, novel surface fluorinated EVA (F-EVA) film with well-defined fluorinated surface structure and good mechanical properties of substrate was prepared via sequential surface reactions, which are controlled alcoholysis reaction with sodium ethoxide and located fluorination reaction with2,3,3,3-tetrafluoro-2-[1,1,2,3,3,3-hexafluoro-2-(heptafluoropro-poxy)propox-y] propionyl fluoride, respectively. Through this functional fluorination, perfluoroalkyl ether chains with a high surface density and precise localization could be covalently bonded to the poly (ethylene-vinyl acetate) film surface, forming a new surface layer with a variety of new functional properties. The F-EVA film was studied by ATR-IR, XPS to further confirm its surface structures, besides, contact angle test was conducted to envaluate its hydrophobicity.To explore the application potential of the F-EVA, hemocompatibility of the resultant films were evaluated by hemolysis test, platelet adhesion test, blood adhesion test and animal test in detail. Results indicated that the well-defined F-EVA film surface displayed low hemolytic activity, no damage to red blood cells, no platelet adhesion and no plasma protein fractions due to its extremely low surface tension which results from the special micro-electric field and oxygen compatibility of perfluoroalkyl ether layer. The newly yielded highly transparent film with unique properties exhibits a great potential in applications on biomedical materials in view of its flexible substrate and unique biocompatible surface.