Abstract: A process for making a radial multi-block copolymer, comprising: (a) anionically polymerizing styrene monomer A1, at least one monovinylarene monomer A2 other than styrene and at least one conjugated diene monomer B using a lithium-based initiator to form block copolymer chains; (b) adding a metal alkyl compound other than the lithium-based initiator after initiating anionic polymerization in step (a), wherein the molar ratio of the metal alkyl compound to lithium is greater than about 2.0; and (c) adding a coupling agent having more than two functional groups to form the radial multi-block copolymer, wherein the radial multi-block copolymer comprises a residue Z derived from the coupling agent and block copolymer chains from step (b) coupled to the residue Z.

Abstract: A radial multi-block copolymer composition comprising a polystyrene block A1, a hard block A2 comprising another type of monovinylarene monomer, two soft blocks B, and B2 of conjugated diene monomer and a coupling agent, the composition of the radial multi-block copolymer having the structure (B1A1A2B2)nZ, where the weight percent of n=5+ is greater than about 40 and Z is a residue of the coupling agent. A process comprising (a) anionically polymerizing styrene monomer Al, at least one monovinylarene monomer A2 other than styrene, and at least one conjugated diene monomer B1 to form multi-block copolymer chains having the structure (B1A1A2), wherein the amount of monovinylarene monomer A2 is from about 0.