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

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.