Patent ID: 7691945
Filing Date: 2010-04-06
Classification: C08F,C09J

Abstract:
1. A method for preparing a radial multi-block copolymer including a tapered block as represented by the following formula 1: wherein pA is a polystyrene block; pT is a poly(isoprene-styrene)tapered block; pB is a polyisoprene block; pC is a polybutadiene block; X is the residue of a multi-functional coupling agent used in preparation of the radial multi-block copolymer; m and n are integers greater than 1 and represent the number of branches associated with X; and wherein the content of pT=the content of pTA+the content of pTB; the content of pA+the content of pTA=10 to 50 wt. % of the radial multi-block copolymer; 0.1<the content of pC<10 wt % of the radial multi-block copolymer; and 0.002<the content of pT<20 wt. % of the radial multi-block copolymer; pTA is the polymerized styrene component of pT and wherein pTB is the polymerized isoprene component of pT; the method comprising: (a) polymerizing a vinyl aromatic monomer using an organolithium initiator and a polar organic compound as a randomizer in the presence of an inert hydrocarbon solvent to synthesize a polyvinyl aromatic living polymer; (b) adding an isoprene monomer for polymerization before using up the vinyl aromatic monomer added in the step (a), to synthesize a tri-block living polymer including the tapered block of the isoprene and vinyl aromatic monomers and the isoprene block sequentially bonded to the polyvinyl aromatic block; (c) adding a multi-functional coupling agent to the tri-block living polymer obtained in the step (b) to activate a coupling reaction; (d) further adding a butadiene monomer in the step (c); and (e) adding a reaction terminator to end the reaction completely.