A composition and methods for making the same. The composition includes an isoolefin having from 4 to 7 carbons, a first styrene, and a second styrene alkylated with a diene to have a pendant double bond. A copolymer having units derived from an isoolefin having from 4 to 7 carbons and an alkylstyrene can be reacted with a diene to provide the composition. The reaction of the copolymer with the diene can be reacted in the presence of a catalyst at a temperature of about 80° C. to about 200° C.