Thermoplastic Polyimides With Enhanced Processability and Thermal Stability via Molecular Structure Modulation

ABSTRACT Thermoplastic polyimides (PI) are attractive for wide‐ranging industrial applications owing to easier processability compared to traditional thermosetting PI. Unfortunately, most thermoplastic PI is endowed with thermoplasticity and processability by introducing flexible segments at the expense of heat resistance. Herein, a series of thermoplastic PI films with a twisted non‐coplanar structure, flexible ether bond, and pendant methyl group were synthesized via quaternary copolymerization. Controlling the molecular chain structures of such PI films by tuning the molar ratio of dianhydride to diamine was found to offer PI more comprehensive properties. The structure–property relationship of quaternary copolymerized PI with more diversified groups studied in this paper would offer guidance for solving the problem of difficult coexistence of heat resistance and thermoplasticity in thermoplastic PI.