Hard carbon films formed from plasma treated polymer surfaces

Abstract

Hard-carbon films with unique structures, methods for producing the films, and articles coated by the films are provided. These hard-carbon films are synthesized by the plasma surface treatment of a polymer substrate or a polymer-coated substrate in a plasma containing SF x species, where x is less than 6, and may be produced under room temperature, low pressure environments.

1 . A method for producing a hard carbon film on a polymeric surface, the method comprising: 
 (a) exposing the surface to a plasma comprising one or more SF x  species where x may range from 1 to 5; and    (b) converting the polymeric surface into a film comprising at least about 90 atomic percent carbon.    
     
     
         2 . The method of  claim 1 , wherein the polymeric surface comprises carbon, oxygen and hydrogen atoms.  
     
     
         3 . The method of  claim 1 , wherein the polymeric surface is oxidized.  
     
     
         4 . The method of  claim 1 , wherein the polymeric surface is converted into a film comprising at least about 95 atomic percent carbon.  
     
     
         5 . The method of  claim 1 , wherein the surface is exposed to the plasma at a pressure from about 50 to 500 mTorr.  
     
     
         6 . The method of  claim 1 , wherein the surface is exposed to the plasma at a temperature from about 20 to 100° C.  
     
     
         7 . The method of  claim 1 , wherein the surface is exposed to the plasma for no more than about 10 minutes.  
     
     
         8 . The method of  claim 1 , wherein the polymeric surface comprises a polymer selected from the group consisting of poly(acrylic acid), poly(methyl methacrylate) and polycarbonate.  
     
     
         9 . The method of  claim 1 , wherein the polymeric surface comprises a polymer selected from the group consisting of polyethylene, polypropylene and polystyrene.  
     
     
         10 . The method of  claim 1 , wherein the polymeric surface is comprised of a polymeric layer disposed on an underlying substrate.  
     
     
         11 . The method of  claim 10 , wherein the polymeric layer comprises poly(acrylic acid).  
     
     
         12 . The method of  claim 1 , wherein the polymeric surface is exposed to the plasma for a time sufficient to produce a film comprising no more than about 5 atomic percent oxygen.  
     
     
         13 . The method of  claim 1 , wherein the polymeric surface is exposed to the plasma for a time sufficient to produce a film comprising no more than about 1 atomic percent hydrogen.  
     
     
         14 . The method of  claim 1 , wherein the exposure of the polymeric surface to the plasma produces a film comprising no more than about 1 atomic percent fluorine.  
     
     
         15 . The method of  claim 1 , wherein the plasma is substantially free of oxygen.  
     
     
         16 . The method of  claim 1 , wherein the plasma is substantially free of hydrocarbon precursors.  
     
     
         17 . The method of  claim 1 , wherein the polymeric surface is exposed to the plasma for a time sufficient to produce a film having a thickness from about 0.5 to 5 microns.  
     
     
         18 . A surface-modified substrate comprising: 
 (a) a substrate; and    (b) a surface film comprising a cross-linked network of carbon chains disposed on the substrate, wherein the surface film comprises at least  90  atomic percent carbon.    
     
     
         19 . The surface modified substrate of  claim 18 , wherein the surface film comprises a polymer from which hydrogen atoms, oxygen atoms, or a combination of hydrogen and oxygen atoms have been extracted.