Patent ID: 8383764

Claim:
A method for purifying a block copolymer comprising the steps of: providing an arborescent block copolymer comprising a polyisobutylene-based thermoplastic elastomer having polystyrene based end blocks; dissolving the block copolymer in a first solvent system to provide a first solution, wherein the first solvent system comprises one or more solvents capable of dissolving a polyisobutylene-based polymer; combining the first solution with a second solvent system, wherein the second solvent system is a (C 3 to C 10 ) ketone, to provide a precipitated block copolymer in a mother liquor; separating the precipitated block copolymer from the mother liquor to provide a purified block copolymer; adding acetone to the purified block copolymer to provide a mixture of the purified block copolymer and acetone; adding a third solvent system to the mixture of the purified block copolymer and acetone, wherein the third solvent system is a non-solvent with respect to at least two types of blocks of the purified block copolymer, to provide a mixture of the purified block copolymer and the mixture of solvents; and separating the purified block copolymer from the mixture of solvents to provide a further purified block copolymer.