Polyisobutylene-based compositions suitable for making golf balls are provided. The amine-terminated polyisobutylene may be reacted with an isocyanate and amine-terminated curing agent to produce a polyurea composition that may be used as a cover material and/or intermediate casing layer. The resulting ball has improved weatherability. In one version, the golf ball includes a polyurea casing layer and polyurea cover. In a second version, the golf ball includes an ionomer casing layer and polyurea cover. In yet another version, the golf ball includes a polyurea casing layer and ionomer cover.