Patent ID: 6359075
Filing Date: 2002-03-19
Classification: C08F,C08L,C09J

Abstract:
A process for preparing a polymer composition which includes diblock and triblock copolymers comprising:a) polymerizing vinyl aromatic monomer in an inert hydrocarbon solvent in the presence of a first anionic catalyst system until substantially complete conversion to a living vinyl aromatic polymer; b) adding a conjugated diene monomer and allowing copolymerization with the living vinyl aromatic polymer to form a living diblock polymer comprising a first block which substantially comprises the first vinyl aromatic polymer and a second block which substantially comprises a conjugated diene polymer; c) adding a chain transfer agent which terminates at least a portion of the living diblock polymer and forms a second anionic catalyst system; d) adding a conjugated diene monomer, the conjugated diene monomer copolymerizing with the unterminated living portion of the diblock polymer and self polymerizing with the second anionic catalyst to form a living polymer; and e) adding a vinyl aromatic monomer, the vinyl aromatic monomer copolymerizing with the product of step d) to form the diblock and triblock copolymers.