Coarse-graining in simulations of multicomponent polymer systems

Abstract

We investigate the mapping required between the interaction parameters of two different coarse-grained simulation models to ensure a match of the long-range structural characteristics of multicomponent polymeric system. The basis for our studies is the recent work of Morse and workers, which demonstrated the existence of a mapping between the interaction parameters of different coarse-grained simulation models which allow for a matching of the peak of the disordered state structure factor in symmetric diblock copolymers. We investigate the extensibility of their results to other polymeric systems by studying a variety of systems, including, asymmetric diblock copolymers, symmetric triblock copolymers, and diblock copolymer-solvent mixtures. By using the mapping deduced in the context of symmetric diblock copolymers, we observe excellent agreement for peak in the inverse structure between both two popular coarse grained models for all sets of polymeric melt systems investigated, thus showing that the mapping function proposed for diblock copolymer melts is transferable to other polymer melts irrespective of the blockiness or overall composition. Interestingly, for the limited parameter range of polymer-solvent systems investigated in this article, the mapping functions developed for polymer melts are shown to be equally effective in mapping the structure factor of the coarse-grained simulation models. We use our findings to propose a methodology to create ordered morphologies in simulations involving hard repulsive potentials in a computationally efficient manner. We demonstrate the outcomes of methodology by creating lamellar and cylindrical phases of diblock copolymers of long chains in the popularly used Kremer-Grest simulation model.

Structural and Mechanical Properties of Ionic Di-block Copolymers via a Molecular Dynamics Approach

“…A two-step equilibration strategy [19,27,28] is employed to obtain the nanostructured BCPs. First, the polymers and counterions are randomly placed in the simulation box, with an initial number density set as ρ* = 0.8.…”

“…dissipative particle dynamics (DPD) type potential, is applied to quickly form nanostructured morphology. This type of soft-core DPD force field has been widely used to study colloidal particles and polymeric fluids [19,29]. This model allows for us to obtain ordered phase with much less computational time when compared to the Kremer-Grest (KG) model, which is usually employed to obtain refined structures.…”

“…To quickly achieve the microphase segregation, soft-core potentials are often adopted in numerical simulations to first obtain ordered phase. The soft-core potentials are purely repulsive to capture the essential physics of self-assemble behavior [19,20]. Other techniques, such as lattice Monte Carlo (MC) [21], have also been attempted to achieve self-assembling that show faster simulation speed when compared to molecular dynamics (MD) simulations.…”

Influence of molecular weight and degree of segregation on local segmental dynamics of ordered block copolymers

“…In this work, we used molecular dynamics simulations to study the spatially resolved segmental dynamics in ordered lamellar phases of block copolymers. Toward this objective, we employed methodologies that were developed recently in our group, to achieve equilibrated morphologies in multicomponent polymeric systems possessing realistic hard‐core interactions. For our dynamical studies, we chose the popular Kremer‐Grest model .…”

A finite element approach to self-consistent field theory calculations of multiblock polymers

“…The computational cost for even a small system is high enough to render this unsuitable as a general tool. Instead, a coarse-graining approach using an abstracted beadspring model (see figure 1b) as a substitute for the full molecular structure (see figure 1a) is an often used [4,5,6] alternative. In this method, each 'bead' is actually multiple monomer units with individual beads interacting via carefully designed local and nonlocal potentials.…”