Effect of orientation of phosphinate pendant on the transparency of polyimides: Design and synthesis of phosphinated diamines with a bulky ortho substitution for high-Tg, transparent polyimides

摘要

Aromatic polyimides (PIs) are well-known as high performance material because of their excellent thermal and mechanical properties. They are widely applied in electronics and aerospace industries. Despite their outstanding properties, most PIs are typically yellow to amber in color because of the conjugation of the polymer chain and the formation of intermolecular/intramolecular charge transfer complex (CTC). This feature limits their application in optics such as flexible solar radiation protectors and orientation films in liquid crystal display devices. Studies have reported that the incorporation of bulky pendants can reduce the CTC effect.^1–9