The stereoregular poly(methyl methacrylate)/poly(vinyl chloride) blends with a wide formulation range are extensively simulated using the coarse-grained (CG) molecular dynamics (MD) method. To improve the representability, the bonded CG potentials are re-parameterized against the atomistic simulated melt systems whereas the nonbonded CG potentials are adopted as developed in our previous work. Based on the CG potentials, the MD simulations reproduce all the local distributions of pure systems and the miscibility of mixed systems. Moreover, the global conformational properties are also closer to the target ones than those obtained using the previous CG potentials. The changes in density and volume upon mixing are computed together with the energies of mixing. They are all negative over the entire composition range and indicate stronger intermolecular interactions between distinct components than those between identical components. In particular, it is found that upon mixing the changes in density are insensible to chain tacticity but the changes in volume and the energies of mixing do, which quantitatively confirms that both inter-molecular interactions and free-volumes mainly contribute to the observed phase behaviors. Such models and methods reported herein can be used to quickly optimize formulations of polymer blends. (c) 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 203-212