Photopolymerization of acrylonitrile in concentrated aqueous zinc halide solutions

Crosslinked polyacrylonitrile (PAN) was obtained with a high yield from the photoinduced polymerization of acrylonitrile (AN) in concentrated aqueous zinc chloride solution. It was found that the presence of zinc chloride res ults in the promotion of the radical generation in the photoinitiation proc ess as well as an increase in the rate of propagation. Any attempt to isola te the polymer from the reaction mixture was not successful due to the inso lubility of the polymer to any conventional solvents to polyacrylonitrile ( PAN); therefore, the reaction mixtures, consisting of PAN, zinc chloride, a nd water-which are referred to as the polymer hybrid system-was used withou t further purification. The effect of other zinc halides on the polymerizat ion such as zinc bromide and zinc iodide was also investigated in connectio n with the photoinitiation mechanism, which reveals that the complex (Zn+(AN)(x)( OH-)(y)Cl4-(x+y)) is the species that is responsible for the photo initiation. It was found that the transparent, stretchable polymer hybrid s ystems are electric conductive and turn to black upon heating to 160 degree s C due to the conversion of the nitrile group of PAN to tetrahydronaphthyr idine rings. (C) 2000 John Wiley & Sons, Inc.