Abstract: One embodiment of the invention provides a method of manufacturing a filter material such as carbon suitable for use in a smoking article. The method includes modifying the filtration properties of the filter by altering the surface of the filter material. The surface alteration is performed by plasma processing and can be used, for example, to increase the acidic or basic properties of the surface. Another embodiment of the invention provides a filter produced by such a method.

Abstract: Films, layers, tapes, plates, and similar structures of metal or of plastic materials, coated with thin polyfluorocarbon films. These films, tapes, etc., are characterized in that no other materials are interposed; the polyfluorocarbon films are adherent and not porous, and have controlled wettability characteristics. The polyfluorocarbons have the formula (CF.sub.x).sub.n, wherein x is within the range of from 0.3 to 2.0, and are directly obtained on the substrate by the plasma-polymerization of gaseous streams of C.sub.2 F.sub.6 and H.sub.2 ; C.sub.2 F.sub.6 and C.sub.2 F.sub.4 ; CF.sub.4 and H.sub.2 ; CF.sub.4 and C.sub.2 F.sub.4 ; or of C.sub.2 F.sub.4. The metal substrate may be, e.g., Al, Cu, Fe, tin-coated Fe, Si, noble metals and alloys thereof. The substrate of plastic materials may be constituted, e.g., by polytetrafluoroethylene, polypropylene, polyethylene, polyphenyloxide, polycarbonate, and neoprene.

Abstract: Films, layers, tapes, plates, and similar structures of metal or of plastic materials, coated with thin polyfluorocarbon films. These films, tapes, etc., are characterized in that no other materials are interposed; the polyfluorocarbon films are adherent and not porous, and have controlled wettability characteristics. The polyfluorocarbons have the formula (CF.sub.x).sub.n, wherein x is within the range of from 0.3 to 2.0, and are directly obtained on the substrate by the plasma-polymerization of gaseous streams of C.sub.2 F.sub.6 and H.sub.2 ; C.sub.2 F.sub.6 and C.sub.2 F.sub.4 ; CF.sub.4 and H.sub.2 ; CF.sub.4 and C.sub.2 F.sub.4 ; or of C.sub.2 F.sub.4. The metal substrate may be, e.g., Al, Cu, Fe, tin-coated Fe, Si, noble metals and alloys thereof. The substrate of plastic materials may be constituted, e.g., by polytetrafluoroethylene, polypropylene, polyethylene, polyphenyloxide, polycarbonate, and neoprene.