Solvent-Resistant Self-Crosslinked Poly(ether imide)

Poly(ether imide) (PEI) is a high-performance polymer with outstanding thermal stability, mechanical strength, and processability, but a critical drawback of poor solvent resistance. Exposure to solvents including chloroform, dimethylformamide, dichloromethane, and N-methyl pyrrolidone severely compromises the mechanical and thermal performances. Herein, we report a method for preparing thermally crosslinked PEI (X-PEI) from azide-terminated PEI (N-3-PEI-N-3) synthesized via a one-pot diazotization-azidation reaction. X-PEI affords unprecedented solvent resistance unpossessed by conventional PEIs, as well as solution processability unrivaled by counterpart high-performance polymers such as polyimide. The glass transition temperature, storage modulus, and swelling ratio correlate positively with crosslinking density, which is determined by the molar mass and azide concentration of N-3-PEI-N-3. This work advances the chemistry of high-performance polymers. The method is generic and applicable to other engineering polymers.