Dependence of polymer electronic structure on molecular architecture

Abstract

A review of the influence of macromolecular architecture on the electronic structure of polymers is presented. Calculations of the density of valence electron states (DOVS) based on the CNDO/S3 molecular orbital model are presented for polyacetylene, poly(p-phenylene), poly(p-phenylene vinylene), poly(p-phenylene sulfide), poly(2,5-thienylene), poly(1,6 heptadiyne), and poly(p-xylylene). These DOVS are shown to provide good descriptions of measured valence electron photoemission spectra in all cases for which such spectra are available. The model is applied to demonstrate the occurrence of short chain segments in mixed cis-trans polyacetylene. Relationships between macromolecular architecture and characteristic features in the photoemission spectra are demonstrated. In particular, criteria leading to extended pi-electron states are identified.