Effective Soft-Core Potentials and Mesoscopic Simulations of Binary Polymer Mixtures

TL;DR

This paper develops an analytical, transferable soft-core potential for mesoscopic simulations of binary polymer mixtures, enabling accurate large-scale structure predictions across various conditions.

Contribution

It introduces a formalism based on the Ornstein-Zernike equation to derive effective potentials for coarse-grained polymer models, enhancing transferability and applicability.

Findings

Quantitative agreement with united atom simulations in athermal conditions

Ability to simulate larger scales than united atom methods

Accurate structure prediction near phase transition

Abstract

Mesoscopic molecular dynamics simulations are used to determine the large scale structure of several binary polymer mixtures of various chemical architecture, concentration, and thermodynamic conditions. By implementing an analytical formalism, which is based on the solution to the Ornstein-Zernike equation, each polymer chain is mapped onto the level of a single soft colloid. From the appropriate closure relation, the effective, soft-core potential between coarse-grained units is obtained and used as input to our mesoscale simulations. The potential derived in this manner is analytical and explicitly parameter dependent, making it general and transferable to numerous systems of interest. From computer simulations performed under various thermodynamic conditions the structure of the polymer mixture, through pair correlation functions, is determined over the entire miscible region of the phase diagram. In the athermal regime mesoscale simulations exhibit quantitative agreement with united atom simulations. Furthermore, they also provide information at larger scales than can be attained by united atom simulations and in the thermal regime approaching the phase transition.