Preparation of Stereoblock Copolymer Containing Isotactic Acrylonitrile -(CH2-CH(CN))n- and α-Chloroacrylonitrile -(CH2-CCl(CN))m- Components in Its Copolymer Backbone by γ-Irradiation...

A novel synthesis of stereoblock copolymer containing highly isotactic acrylonitrile (AN) sequences in its polymer backbone was reported. That is, γ-irradition post-polymerization of AN/urea canal in the solid state was a typical living radical system, as evidenced by various modified experiments. After finishing the polymerization, freshly distilled α-chloroacrylonitrile (CAN) was introduced with methanol, and the mixture was allowed to copolymerize at low temperatures. The content of PCAN component introduced in this way was estimated to be about 23%mol by a calibration curve. When the sample was heated under mild heating conditions (under vacuum, at 80°C, for overnight), color changed from white to pale pink to bright purple with maintaining the solubility into DMF, etc. UV spectra indicate that the several peaks appeared in a longer wave length (400~650nm), which was explained in terms of the formation of conjugated double bonds -(CH=CH(CN))_n-on a polymer backbone via elimination (HCl). The length (n) of the conjugated double bond was estimated to be about 20-25 numbers in one typical case. Under severe oxidative-heating conditions, however, the powder lost the solubility with accompanying the color change to reddish brown. A useful candidate for the precursor of super-conducting material, isotactic PAN and atactic PCAN stereoblock sequences on its backbone, was prepared in this way. [ABSTRACT FROM AUTHOR]