Electrical conductivity of iodine adducts of nylon 6 and other non-conjugated polymers

Abstract

Iodine-nylon 6 adducts containing 70 to 90wt% iodine have been prepared by heating iodine and nylon 6 at 115 and 145° C. The electrical conductivity (σ) of the adduct increases with increase in the iodine content and the iodine-nylon 6 adduct containing 90wt% iodine and prepared at 145° C gives σ = 10−3 S cm−1 at 25° C. Infrared, nuclear magnetic resonance (1H and13C{1 H}), and powder X-ray diffraction analysis of the adduct show a profound change of the structure around the amide group of nylon 6 and suggest the formation of a-C=NH+-group in the reaction of nylon 6 with iodine. The temperature dependences of σ of the idoinenylon 6 adducts prepared at 115° C give activation energies of 51 to 92 kJ mol−1 depending on the iodine content. Addition of carbon powder to the iodine-nylon 6 adduct causes an increase in electrical conductivity. Other polymers (aliphatic and aromatic nylons, poly(vinyl alcohol), poly (tetrahydrofuran), poly(N-vinylpyrrolidone), poly (4-vi nylpyridine), and poly(acrylonitrile)) which have lone pair or π-electrons also form iodine adducts containing 70 to 95 wt % iodine and the adducts show an electrical conductivity in the range of 10−5 to 10−2 S cm−1. Among the iodine adducts, those of poly(vinyl alcohol) and poly (tetra hydrofuran) show electrical conductivities as high as 1.5 X 10−2 S cm−1 when the adducts contain about 90 wt% iodine.