Preparation and surface characterization of poly(vinyl acetate) brush

Surface-initiated radical polymerization of vinyl acetate (VAc) from silicon wafer was carried out using degenerative chain transfer system promoted by alkyl iodides. The silicon wafer immobilized with the radical initiator was prepared by the chemical vapor adsorption of 6-triethoxysilylhexyl 2-bromoisobutyrate on hydrophilic silicon wafer. The initiator-immobilized silicon wafer, AIBN, n-butyl iodide (BuI), I₂, and VAc were introduced into a glass tube, and then degassed by repeating the freeze-and-thaw process. The polymerization was carried out at 343 K for 18 hrs under argon atmosphere to give a polymer brush on substrate and a free polymer from BuI at the same time. The thickness of polymer brush was estimated by AFM and ellipsometry. The grafting density was calculated to be ca. 0.14 chains/nm ² by linear relationship of the thickness and the number-average molecular weights, which was determined by GPC of free polymer.