An adhesive composition is described comprising a tackifier and at least one grafted isobutylene copolymer. The grafted isobutylene copolymer has the formula: R1—(R2—Z) wherein R1 represents an isobutylene copolymer, R2 is a covalent bond or multivalent alkylene or arylene, and Z is a grafted polymer. Z is typically a homopolymer of copolymer comprising alkene repeat units, aralkylene repeat units, or a combination thereof. Also described are adhesive coated articles, methods of making adhesive coated articles, and grafted isobutylene polymers.