catheters for long term implantation having polymer surfaces in face - to - face contact which are provided with a thin film coating of a glow discharge plasma polymerized fluorocarbon to prevent adhesion of the contacting surfaces . the polymerized fluorocarbon film , between about 50 and 1000 angstroms in thickness , is bonded to the substrate material giving a low surface energy without changing its bulk properties . the low surface energy will prevent adhesion of cured polymer surfaces in contact and act as a lubricant . the smooth pinhole - free films will control or prevent diffusion into or out of the bulk material . these biocompatible films provide an alternative use for polymers whose bulk properties are unacceptable but whose surface properties are desirable .