Flame-treating process

This invention provides a method of modifying the surface of a polymeric substrate, e.g. to improve the wettability of the polymer film surface and/or affix silicon-containing structures to the substrate surface, comprising exposing the substrate to a flame. The flame is supported by a fuel and oxidizer mixture that includes at least one silicon-containing compound that functions as a fuel and is in an effective amount for modifying the surface of the polymeric substrate. Also disclosed are substrates with surfaces that are modified by exposing the substrate to a flame that is supported by the process of the invention. Large increases in the ASTM wetting test, e.g., greater than 13 mJ/m2 over that reported with conventional flame-treating processes, have been observed in polymeric substrates treated according to this invention. In addition, significant amounts of silicon-containing chemical groups affixed to polymeric substrate surfaces have been observed.