The radiation-induced polymerization of iso butene

Abstract

Iso butene polymerizes at low temperatures when exposed to high-energy radiation. The resulting polymer, of high molecular weight, is similar in all respects to normal poly iso butene. The fractional conversion of monomer per unit radiation dose is independent of the intensity of radiation and increases as the temperature is lowered. The polymerization is inhibited by di- iso butene which also inhibits the normal ionic polymerization and by both oxygen and benzoquinone which normally inhibit free radical polymerization but not ionic polymerizations. Carbon tetrachloride has little effect on the rate of the radiation-induced polymeriza­tion or on the average degree of polymerization of the product. The reaction is very sensitive to surface and may be in part intrinsically heterogeneous. All the evidence points to a carbonium ion propagation mechanism for the propagation of polymer chains which may be initiated either by primary ion-radicals formed from iso butene or by carbonium ions formed on disruption of the ion-radicals.