The possibility of intra-molecular nematic order via chain folding in perylene-containing polyimides: a molecular dynamics study

Abstract

Perylene containing main-chain polyimides are candidate materials for the photogenerator layer of electrophotographic devices. These polymers are semi-crystalline as synthesized. Annealing improves the crystallinity while causing subtle changes in the X-ray diffraction pattern and a red-shift in the UV–vis absorption spectrum. Molecular dynamics simulations of linear chains of …Pe–C₁₂–Pe… led to chain folded collapsed structures. It is known that a minimum chain length of 150 CH₂ units is required, in the case of linear alkanes, for stable folding to occur. However, the strong attractive π interaction between the perylene units causes the chain to fold, with as few as 12 CH₂ spacer units. This shows that both intra and intermolecular nematic order can occur in these systems, the former caused by chain folding.