a nitrile - containing material is bonded to the surface of a rubber substrate in order to increase the wettability of the surface . a rubber substrate is placed in the afterglow region of an electrodeless glow - discharge chamber . a nitrile - containing material such as an acrylonitrile monomer is introduced into the chamber , causing the monomer to polymerize and bond to the surface of the rubber substrate . in one embodiment , the surface of the rubber is etched with sulfuric acid prior to bonding the nitrile - containing material to the surface .