Poly[(p-bromomethyl)styrene]-b-polyisobutylene-b-poly[(p-bromomethyl)styrene]s prepared by sequential monomer addition technique of living cationic polymerization were connected with living syndiotactic (st)-poly(methyl methacrylate) macroanions via Wurtz-Grignard-type coupling. In nonpolar medium (toluene), the coupling resulted in the formation of chemically crosslinked network. In polar solvent (tetrahydrofuran), however, a comb-like triblock copolymer with properties of thermoplastic elastomer was obtained.