US Patent 7109272 Block copolymer and thermoplastic resin composition

A styrene/hydrogenated diene block copolymer characterized in that it has in side chains at least one kind of functional groups selected from the group consisting of a boronic acid group and a boron-containing group capable of converting into a boronic acid group in the presence of water, the content of the functional groups in the copolymer is 100 to 2,000 μeq/g, and the weight ratio of the styrene units to hydrogenated diene units contained in the copolymer is from 5/95 to 70/30. By thus incorporating a sufficient amount of boron-containing groups, a highly reactive styrene/hydrogenated diene block copolymer is provided.