PREPARATION METHOD OF RADIAL BLOCK COPOLYMER

摘要

PURPOSE: A method for preparing a radial block copolymer is provided, to obtain a copolymer having an antiaging property and an increased branch number with avoiding gelation. CONSTITUTION: The method comprises the steps of polymerizing a vinyl aromatic monomer with an organolithium initiator in an nonactive hydrocarbon solvent until the monomer is consumed completely to prepare a living polymer; adding an isoprene monomer to the living polymer and polymerizing them until it is consumed completely to prepare a diblock living polymer; and adding ethylene to the diblock living polymer in the presence of a Lewis base and adding a tri- or more valent coupling agent to prepare a triblock copolymer by coupling reaction of ethylene end, or adding simultaneously the tri- or more valent coupling agent and ethylene to the diblock living polymer in the presence of a Lewis base to prepare a triblock copolymer by coupling reaction. Preferably the vinyl aromatic monomer is styrene.