The compatibility of six groups 12 miktoarm polystyrene-block-poly(methyl methacrylate) copolymers is studied at 383, 413, and 443 K via mesoscopic modeling. The values of the order parameters depend on both the architectures of the block copolymers and the simulation temperature, whereas the change tendency of the order parameters is nearly the same at 413 and 443 K. Obviously, temperature presents more obvious effect on long and PMMA-rich chains. A study of plain copolymers doped with nanoparticles shows that the microscopic phase is influenced by not only the properties of the nanoparticles, such as the size, number, and density, but also by the composition and architecture of copolymers. Increasing the size and the number of the nanoparticles used as a dopant plays the most significant role on the phase morphologies of the copolymers at lower and higher temperatures, respectively. Especially, the 13214-type copolymers, which are PMMA-rich composition, present microscopic phase separation as varying degrees of lamellar phase morphologies at 443 K, alternated with PS and PMMA component. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 127: 1561-1568, 2013