the invention relates to a method for modifying at least a part of the surface of a fluorine - containing plastic , which comprises making the surface hydrophobic by 1 ) ion - etching the plastic surface ; and 2 ) subsequently treating the plastic surface with flow discharging . the invention also relates to a fluorine - containing plastic having a surface which is at least partially hydrophobe - modified by ion - etching followed by glow discharging , and to materials , such as bio - materials , in which the plastic is incorporated .