The radiation-induced polymerization of <i>iso</i> butene

Abstract

Abstract Isobutene polymerizes at low temperatures when exposed to high-energy radiation. The resulting polymer, of high molecular weight, is similar in all respects to normal polyisobutene. 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-isobutene 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 isobutene or by carbonium ions formed on disruption of the ion-radicals.