Systematic and simulation-free coarse graining of multi-component polymeric systems: Structure-based coarse graining of binary polymer blends

Abstract

We proposed a systematic and simulation-free strategy for the structure-based coarse graining of multi-component polymeric systems using the polymer reference interaction site model theory, and as an example applied it to a simple model system of binary polymer blends. Our structure-based coarse graining ensures that the original and coarse-grained (CG) systems have the same intra- and intermolecular pair correlation functions involving the CG segments (each representing the center-of-mass of a group of consecutive monomers on the same chain in the original system). When applied to binary polymer blends, it does not change the spinodal curve (thus also the critical point), regardless of the original model system and closure used. We also quantitatively examined how the effective non-bonded pair potentials between CG segments and the thermodynamic properties of CG systems vary with the coarse-graining level. As expected, the structure-based coarse graining cannot give thermodynamic consistency (i.e., the same interchain internal energy per chain and virial pressure) between the original and CG systems at any coarse-graining level.