A copolymer is formed from an isoolefin having from 4 to 7 carbon atoms and an alkylstyrene. The copolymer has a substantially homogeneous compositional distribution. The copolymer has from about 8 to about 12 wt % of alkylstyrene and at least 85 wt % of isoolefin. The copolymer is preferably halogenated with about 1.1 to about 1.5 wt % of a halogen. The copolymer may in elastomeric nanocomposites. To obtain a good dispersion of the nanoclay in a formulated compound, at least one cure accelerator is selected from the group consisting of mercaptobenzothiazole disulfide, mercaptobenzothiazole, cyclohexyl benzothiazole disulfide, dibutyl thiourea, tetramethylthiuram disulfide, 4-4-dithiodimropholine, zinc dimethyldithiocarbamate, and zinc dibutylphosphorodithiate.