ELECTRICALLY CONDUCTIVE METAL SULFIDE POLYMER COMPOSITES PREPARED BY USING ORGANOSOLS OF METAL SULFIDES

Electrically conducting metal sulfide (MS; M = Cu, Cd, Zn, etc.)-polymer (poly(acrylonitrile), poly(vinyl butyral), poly(vinylidene fluoride), poly[arylene(1,3-imidazolidine-2,4,5-trione-1,3-diyl)], etc.) composite films are obtained by using organosols containing MS and the polymer. The CuS-polymer composite films exhibit electrical conductivities of 1-30 S cm-1 at 40 wt % CuS. The CuS-poly[arylene(1,3-imidazolidine-2,4,5-trione-1,3-diyl)] composite film containing 20-40 wt % CuS is thermally stable up to 250-degrees-C, has good mechanical strength (breaking stress of ca. 10(8) Pa), and serves as shielding materials for electromagnetic waves intercepting 99% of the electromagnetic wave at 200 MHz. CdS-polymer composites exhibit electrical conductivities of 10(-8)-10(-4) S cm-1, and ZnS-, alpha-HgS-, NiS-, PdS-, MnS-, and mixed metal sulfide Zn(Cd)S-polymer composites have electrical conductivities in the range 10(-9)-10(-4) S cm-1. CuS-polymer and CdS-polymer composites indicate p-type and n-type electrically conductive properties, respectively. The temperature dependence of the electrical conductivity of the MS-polymer composites obeys Arrhenius type equations, giving activation energies of -5.7 kJ mol-I for the CuS-poly(vinyl alcohol) composite (wt % of CuS = 31), 2.8 kJ mol-1 for the CuS-80:20 copolymer of vinylidene chloride and acrylonitrile composite (wt % of CuS = 19), and 32 kJ mol-1 for the CdS-poly(vinylidene fluoride) composite (wt % of CdS = 43). The electric current is believed to flow through a network of MS formed in the composites. Preparation of MS-polymer composite films on the surface of substrates (e.g., copper sulfide and n-Si) affords heterojunctions, which show rectification of electric current with rate values of 30-102.