Influence of Cohesive Energy on the Thermodynamic Properties of a Model Glass-Forming Polymer Melt

Abstract

Monomer chemical structure and architecture represent the most important characteristics of polymers that affect basic molecular parameters (such as the microscopic cohesive energy parameter ϵ and chain persistence length) and that correspondingly govern the bulk physical properties of polymer materials. Here, we focus on elucidating how the microscopic parameter ϵ influences the bulk thermodynamic properties of polymer melts by using molecular dynamics simulations for a standard coarse-grained bead–spring model of unentangled polymer melts under both constant volume and constant pressure conditions. Basic dimensionless thermodynamic properties, such as the cohesive energy density, thermal expansion coefficient, isothermal compressibility, and surface tension, are found to be universal functions of the temperature scaled by ϵ, and thermodynamic signatures for the onset and end of glass formation are identified based on observable features from the static structure factor. We also find that general trends ...