Isomerization polymerization of 2‐vinyl‐1,3‐dioxolane by α,α′‐azobisisobutyronitrile or by γ‐ray irradiation

Abstract 2‐Vinyl‐1,3‐dioxolane was polymerized by use of α,α′‐azobisisobutyronitrile (AIBN) or by γ‐ray irradiation. The polymer obtained was white amorphous powder which melted at ca. 70°C. and was soluble in chloroform, acetone, and p‐dioxane. The infrared spectrum of the polymer indicated peaks at 1735 cm.−1 characteristic of the carbonyl group, and at 1200–1000 cm.−1 characteristic of the acetal group, while no absorption at 990 and 3100 cm.−1 due to the vinyl group was observed. The spectra of the polymers obtained by AIBN and by γ‐ray irradiation were essentially identical. The saponified product of the polymer was white powder and its reduced viscosity was a little larger than that of the original polymer. These results indicate that the polymer has no ester unit in the main chain. The results of gas chromatographic analysis of the saponified product of the polymer, indicate the presence of a small amount of ethyl alcohol. The results of the saponification showed that the ester content in the polymer varied from 7 to 25% depending upon the polymerization temperature. These results indicate that 2‐vinyl‐1,3‐dioxolane polymerized by AIBN or by γ‐irradiation with two modes of vinyl and hydrogen migration, yielding a copolymer having the unit structures magnified image