Electronic Structure of Polymer Dielectrics: The Role of Chemical and Morphological Complexity

The electronic structure of polymers contains signatures that correlate with their short-term and long-term integrity when subjected to large electric stresses. A detailed picture of the electronic structure of realistic models of polymers has been difficult to obtain, mainly due to the chemical and morphological complexity encountered in polymers. In this work, we have undertaken a comprehensive analysis of the electronic structure of six model polymers displaying chemical and morphological diversity, namely, polyethylene (PE), polypropylene (PP), polystyrene (PS), poly(methyl methacrylate) (PMMA), polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), using first-principles density functional theory computations and classical molecular dynamics simulations. In particular, we have studied the role of monomer chemistry, tacticity and large-scale morphological disorders in shaping the electronic structure of these polymers. Appropriate connections and comparisons between the computed results and the available experimental data have also been provided. Critical insights on physico-chemical and electronic structures relationships are revealed, providing a pathway for understanding the factors that control electrical conduction and degradation of polymers.