The phase morphologies of six kinds of designed poly(styrene-block-methyl methacrylate) copolymers were studied at 383, 413, and 443 K by mesoscopic modeling. The values of order parameter depended on both the structures of block copolymers and the simulation temperatures, whereas values of order parameter of the long chains were higher than those of the short ones; temperature showed a more obvious effect on long chains than on the short ones. These plain copolymers doped with PS or PMMA homopolymer showed different order parameter values. When the triblock copolymer was composed of the same component at both ends and was doped with a homopolymer with the same component as that in the middle of triblock copolymer, such as B6A3B6 doped with A3, B12A6B12 doped with A6, A6B12A6 doped with B12, and A3B6A3 doped with B6, it showed the highest order parameter values. The study of copolymers doped with nanoparticles showed that the mesoscopic phase was influenced by not only the properties of the nanoparticles, such as the size and density, but also the compositions of copolymers. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119: 265-274, 2011