DEPOSITION OF COPPER SULFIDE ON THE SURFACE OF POLY(ETHYLENE-TEREPHTHALATE) AND POLY(VINYL ALCOHOL) FILMS IN THE AQUEOUS-SOLUTION TO GIVE ELECTRICALLY CONDUCTIVE FILMS

Heating an aqueous solution containing CuSO4 (0.10 M) and Na2S2O3 (0.10 M) at 60 and 70-degrees-C causes precipitation of copper sulfide (Cu(x)S) as a dark brown or black solid. Elemental analyses and XPS measurement show that the x value in the product varies from 1.7 to 1.0 depending on the preparation conditions. Similar reaction of CuSO4 and Na2S2O3 in the presence of poly(ethylene terephthalate) (PET) films pretreated with a methanol solution of poly(ethyleneimine) (PEI) gives copper sulfide coated PET films (Cu(x)S-PET) which show the surface resistivity of 20-1000 OMEGA/square depending on the reaction conditions. Scanning electron micrographs of the Cu(x)S-PET film show that surface of the PET films is coated with the copper sulfide layer with ca. 400-nm thickness. The PET films whose surface is coated with poly-(urethane) and those pretreated with silicon-containing compounds such as (gamma-aminopropyl)-triethoxysilane and {gamma-[N-(beta-aminoethyl)amino]propyl}trimethoxysilane are also converted to the electrically conductive Cu(x)S-PET films by immersing them at 60-70-degrees-C in an aqueous solution Of CuSO4 and Na2S2O3. Exposure of the Cu1.7S-PET film to H2S atmosphere causes decrease in the surface resistivity from 80 OMEGA/square to 15 OMEGA/square accompanied by change of the color of the film from brown to green. Poly(vinyl alcohol) (PVA) and poly(2-cyano-1,3-phenylene oxide) (ID-300) films also undergo deposition of Cu(x)S on the surface by immersing them in the aqueous solution containing copper sulfides to give electrically conducting films.