Quantitative analysis of chain packing in polymer melts using large scale molecular dynamics simulations

Abstract: We have carried out a quantitative analysis of the chain packing in polymeric melts using molecular dynamics simulations. The analysis involves constructing Voronoi tessellations in the equilibrated configurations of the polymeric melts. In this work, we focus on the effects of temperature and polymer backbone rigidity on the packing. We found that the Voronoi polyhedra near the chain ends are of higher volumes than those constructed around the other sites along the backbone. Furthermore, we demonstrated that the backbone rigidity (tuned by fixing the bond angles) affect the Voronoi cell distribution in a significant manner, especially at lower temperatures. For the melts consisting of chains with fixed bond angles, the Voronoi cell distribution was found to be wider than that for the freely jointed chains without any angular restrictions. As the temperature is increased, the effect of backbone rigidity on the Voronoi cell distributions diminishes and becomes similar to that of the freely jointed chains. Demonstrated dependencies of the distribution of the Voronoi cell volumes on the nature of the polymers are argued to be important for efficiently designing the polymeric materials for various energy applications.