Polyisobutene

Polyisobutene is a class of organic polymers prepared by polymerization of isobutene. The polymers often have the formula Me₃C_nH. They are typically colorless gummy solids.
Cationic polymerization, initiated with a strong Brønsted or Lewis acid, is the typical method for its production. The molecular weight of the resulting polymer determines the applications. Low MW polyisobutene, a mixture of oligomers with M_ns of about 500, is used as plasticizers. Medium and high MW polyisobutenes, with M_n ≥ 20,000, are components of commercial adhesives.