Modelling of structural and physicomechanical properties of poly-paraphenylene using molecular orbital and molecular mechanical methods

Conducting polymers are important technological materials that are finding increasing use in batteries and display devices. The conformation and packing of these polymers in the amorphous glassy state are poorly understood, despite the fact that they dictate their most important physical and mechanical properties. The processing of currently known conducting polymers is difficult and there is a strong incentive to increase their processability through blending with other polymers or functionalisation. Developing an ability to predict the structure and structure–property relations of conducting polymers in the bulk will help with the design of new structures that combine processability with favourable electronic properties and facilitate their use in present-day high-technology applications. In this work, we will concentrate on a very important conductive polymer: poly(p-phenylene). Detailed atomistic molecular models have been developed with the help of molecular mechanics and semi-empirical quantum mechanical calculations using Cerius and MOPAC program packages and structural, volumetric, and mechanical properties, e.g., geometrical values, density, have been calculated by simulations on these models. The results from both methods have been compared with simulated and experimental data and conclusions have been drawn on the methodology and the approximations used. This study was used to validate the existing molecular simulation software; to produce force fields, appropriate for the reliable molecular simulation of chemically complex polymer systems; and to develop a new methodology for calculating structure, physical and mechanical properties that will be generally applicable to conductive polymers.