Polymerization of Acrylonitrile-Metal Haiide Complexes in the Frozen State. III. Relationship between Rate of Radiation-Induced Polymerization and Complex Concentration

Photopolymerization of acrylonitrile in concentrated aqueous zinc halide solutions

“…In radiation-induced polymerization a higher rate of polymerization was observed at Ϫ78°C than that carried out at 0°C. 4 It was concluded that the enhancement effect of zinc chloride in the radiation-induced polymerization of AN was ascribed to the complex formation of AN with the zinc ion, whose propagating reactivity is much higher than that of the monomer in the free state. It has been reported that the higher rate of polymerization at the lower temperature when compared to that carried out at higher temperature range was reasonably explained by the increased concentration of the ANzinc ion complex.…”

“…If the process of generation radical species is operative, the rate of polymerization at Ϫ78°C should be much higher than that carried out at 0°C, as was observed in the corresponding radiation-induced polymerization systems. 4 It has been known that the stability of the chloro-zinc ion complex also increases as the temperature is lowered, due to the exothermic nature of the complex formation; however, chloride ion of the complex is preferentially replaced by AN 3 at the low temperature range. Because the complex formation of AN with zinc ion is more exothermic than that of the chloro-zinc ion complex, as a consequence, concentration of the chloro-zinc ion complex 3 decreases with temperature lowering [eq.…”

“…2 The acceleration effect of zinc chloride was also observed in the radiation-induced polymerization of AN, and it was concluded that the acceleration effect of zinc chloride was attributed to the increased rate of propagation due to the complex formation of AN with zinc chloride. [3][4][5] It was found that crosslinked polyacrylonitrile (PAN) is obtained from the photo-induced polymerization of AN in concentrated aqueous zinc chloride solution with a high yield in the absence of any initiator. In this article, we report the results of photoinduced polymerization of AN in the concentrated aqueous solutions of zinc halides such as zinc chloride, zinc bromide, and zinc iodide.…”