Temperature-Transferable Coarse-Grained Potentials for Ethylbenzene, Polystyrene, and Their Mixtures

Abstract

In this article, we present coarse-grained potentials of ethylbenzene developed at 298 K and of amorphous polystyrene developed at 500 K by the pressure-corrected iterative Boltzmann inversion method. The potentials are optimized against the fully atomistic simulations until the radial distribution functions generated from coarse-grained simulations are consistent with atomistic simulations. In the coarse-grained polystyrene melts of different chain lengths, the Flory exponent of 0.58 is obtained for chain statistics. Both potentials of polystyrene and ethylbenzene are transferable over a broad range of temperature. The thermal expansion coefficients of the fully atomistic simulations are well reproduced in the coarse-grained models for both systems. However, for the case of ethylbenzene, the coarse-grained potential is temperature-dependent. The potential needs to be modified by a temperature factor of T / T 0 when it is transferred to other temperatures; T 0 = 298 K is the temperature at which the coarse-grained potential has been developed. For the case of polystyrene, the coarse-grained potential is temperature-independent. An optimum geometrical combination rule is proposed with the combination constant x = 0.4 for mutual interactions between the polystyrene monomer and ethylbenzene molecules in their mixtures at different composition and different temperature.

Nonperiodic stochastic boundary conditions for molecular dynamics simulations of materials embedded into a continuum mechanics domain

“…45 The tabulated potential has been obtained by Iterative Boltzmann inversion, 46 which optimizes the coarse-grained potential to reproduce structural distribution functions of a reference atomistic model. It uses one superatom per chemical repeat unit placed at its center of mass.…”

“…It uses one superatom per chemical repeat unit placed at its center of mass. 45 In atactic PS, the repeat units have different absolute conformations (R and S), which are treated in the model as two different bead types. All simulations were carried out by our software package IBIsCO, which is able to handle tabulated potentials.…”

Challenges in Multiscale Modeling of Polymer Dynamics

“…The obtained entanglement length at 450 K is found to be in agreement with experimental observations. Qian et al [69] chose another mapping scheme (see Figure 11c). The newly obtained potentials can reproduce the isothermal compressibility and structure properties of the PS melts from 400 K to 500 K. Kremer and his co-workers used yet another mapping scheme, as shown in Figure 11d [188,201].…”

“…From these studies, it is important to know that although there are different ways to define the super atom in deriving a coarse-grained model, the static, dynamic or thermodynamic properties of the coarse-grained model should be tested and validated before it is further applied [42]. [195][196][197]; (b) [185,200]; (c) [69]; and (d) [188,201]. Superatom Center…”

“…One of the most powerful methods to study polymer mixtures at equilibrium in an approximate manner is self-consistent field theory [66]. Some of the multiscale modeling methods reviewed in this paper have been extended to study polymer mixtures [67][68][69][70][71][72][73][74][75]. Interested readers may refer to these papers for details.…”