A polymeric material includes a polyisobutylene-polyurethane block copolymer. The polyisobutylene-polyurethane block copolymer includes soft segments, hard segments, and end groups. The soft segments include a polyisobutylene diol residue. The hard segments include a diisocyanate residue. The end groups are bonded by urea bonds to a portion of the diisocyanate residue. The end groups include a residue of a mono-functional amine.