Self-assembly behavior of rod coil rod poly(gamma-benzyl-L-glutamate)-b-poly(ethylene glycol)-b-poly(gamma-benzyl-L-glutamate) (PBLG-b-PEG-b-PBLG) triblock copolymers with various PBLG block lengths in aqueous solution was investigated. The PBLG-b-PEG-b-PBLG triblock copolymers are able to self-assemble into vesicles when PBLG block length is relatively short. Meanwhile, the initial polymer concentration was found to have influence on the self-assembly. Giant vesicles can be observed when the initial concentration is high. Dissipative particle dynamics (DPD) simulations about the vesicles revealed that the rigid rod blocks could be aligned parallelly with each other to form the monolayer vesicles wall. When the PBLG block length in the PBLG-b-PEG-b-PBLG triblock copolymers increases, the aggregate morphologies were observed to transform from vesicles to spherical micelles. Based on the experimental and simulation results, we proposed a possible mechanism of the morphological transitions of the rod-coil-rod triblock copolymer aggregates. (C) 2013 Elsevier Ltd. All rights reserved.