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Temperature Transferable and Thermodynamically Consistent Coarse-Grained Model for Binary Polymer Systems
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DOI：10.1021/acs.macromol.3c00315.png)
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Abstract
En 中文
Forthe simulations of polymer systems, coarse-grained (CG) modelsare often developed to tackle the length and time scale limitationsthat are not feasible by all-atom molecular dynamic simulations. However,due to the necessary simplification or reduction in atomistic degreesof freedom, CG models usually have poor transferability over varioustemperatures, compositions, or thermodynamic states. In this work,the structure-based iterative Boltzmann inversion (IBI) method isfurther developed to obtain temperature transferable and thermodynamicallyconsistent CG potentials for binary polymer systems. In particular,the conventional IBI procedure is first utilized to optimize single-componentCG potentials from homopolymer systems while cross-interaction potentialsfrom a random block copolymer system. Afterward, a thermodynamic integrationmethod is applied to refine the cross-interaction potential betweentwo constituent components in binary systems until the Flory-Hugginsparameter (& chi;) between two components is matched with experimentalvalue. We apply the above optimization procedure for the polystyrene-block-poly-(methyl methacrylate) (PS-b-PMMA)as an example, which is widely studied experimentally, and the & chi;value can be easily obtained in the literature. To validate the transferabilityof the obtained CG potential, systems of both PS and PMMA homopolymers,random block copolymers, diblock copolymers, and PS/PMMA blends withvarious compositions are simulated. Many properties, including themass density, radius distribution function, and bonded distributionfunctions, between CG beads generated from CG simulations match verywell with those from atomistic simulations in the simulated temperaturerange, i.e., from 453 to 500 K. More importantly, phase morphologiesof diblock copolymers and phase diagram of PS/PMMA binary blends overwide temperature and compositional ranges generated from CG simulationsusing our model are in good agreement with experimental results andpredictions from self-consistent field theory.
Keywords:
ITERATIVE BOLTZMANN INVERSION
ORDER-DISORDER TRANSITION
MOLECULAR-DYNAMICS
POLY(METHYL METHACRYLATE)
ATOMISTIC SIMULATIONS
INTERACTION PARAMETER
DIBLOCK COPOLYMER
SAXS ANALYSIS
FORCE-FIELD
POLYSTYRENE