Patent ID: 7534833

Claim:
A radial multi-block copolymer including a tapered block, the radial multi-block copolymer comprising a polystyrene block, a poly(isoprene-styrene)tapered block, a polyisoprene block, and a polybutadiene block, the radial multi-block copolymer being represented by the following formula 1 and having a weight average molecular weight of 200,000 to 500,000: (pA-pT-pB)m-X-n(pC-pB-pT-pA) Formula 1: wherein pA is the polystyrene block; pT is the poly(isoprene-styrene)tapered block; pB is the polyisoprene block; pC is the 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 equal to or greater than 1, representing 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; wherein pTA is the pA component of pT, and pTB is the pB component of pT.