Immobilization of Viologen Moieties on Poly(Acrylic Acid)-Grafted Polyethylene Surface

Abstract

Immobilization of viologen moieties on low-density polyethylene(PE) film was carried out by a surface graft polymerization technique in this study. Graft polymerization of acrylic acid was performed onto the surface of PE film pre-treated with Ar plasma. Following the plasma treatment and the subsequent exposure to air to introduce peroxides onto PE film surface, graft polymerization was allowed to proceed from the polymer peroxides in deaerated acrylic acid aqueous solution. Carboxyl groups of the PAAc-grafted PE film were reacted with epoxy groups of epibromohydrin, to introduce bromoalkyl groups to the surface of PE film. Viologen moieties were introduced onto the surface of PE film by the Menschtkin reaction between bromoalkyl groups and 4,4’-bipyridine, followed by the reaction with n-propyl bromide. The PE film containing viologen moieties exhibited the photochromism. Attenuated total reflection Fourier-transform infrared spectroscopy(ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and UV-visible studies were conducted for characterizing the surfaces of these films during the various stages of the reaction.