A novel (ABCB)(n) type ternary amphiphilic multiblock copolymer was synthesized by stepwise insertion of monomers into the trithiocarbonate-embedded poly(ethylene oxide) (PEO) macro-chain transfer agent (PEO-CTA)(n). (PEO-CTA)(n) was synthesized first by coupling of alpha,omega-dihydroxyl PEO with dicarboxylic trithiocarbonate, then styrene (St) and t-butyl acrylate ((t)BA) were inserted into the (PEO-CTA),, successively to yield (PEO-b-PS)(n) and (PEO-h-PS-b-P(t)BA-b-PS)(n), respectively. After hydrolysis of the (PEO-b-PS-b-P(t)BA-b-PS)(n), the final product (PEO-b-PSb-PAA-b-PS)(n) was obtained. (c) 2006 Elsevier Ltd. All rights reserved.