Patent ID: 8415429

Claim:
A method of forming a monovinylarene-conjugated diene block copolymer, the method comprising: polymerizing a monovinylarene and a conjugated diene in a mixture comprising a diluent; adding as separate additions a first coupling agent and a second coupling agent to the mixture, wherein the monovinylarene-conjugated diene block copolymer formed comprises: a proximal conjugated diene block comprising from about 5 phm conjugated diene units to about 50 phm conjugated diene units; and a plurality of monovinylarene-conjugated diene mixed blocks, wherein each monovinylarene-conjugated diene mixed block contains conjugated diene units and monovinylarene units with a weight ratio of conjugated diene units to monovinylarene units of about 0.05 to about 0.33.