The entropic effects in the comicellization behavior of amphiphilic AB copolymers differing in chain architecture of solvophilic A or solvophobic B parts are studied by means of molecular dynamics simulations. In particular, we studied linear/star and star/star copolymer mixtures. The properties of interest were the critical micelle concentration, the mean aggregation number, the shape of the micelle, which is expressed by the shape anisotropy, the thickness of the corona, and the solvophobic core radius. We found that the critical micelle concentration values for linear/star and copolymer mixtures show a positive deviation from the analytical predictions of the molecular theory of comicellization for chemically identical copolymers. This could be attributed to the effective interactions between copolymers originated from the architectural asymmetry. The effective interactions induce a small decrease in the aggregation number of preferential micelles in linear/star mixtures triggering the nonrandom mixing between the solvophilic moieties in the corona for all mixtures. (c) 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 442-452