Low-Curing Temperature Phenylethynyl-Terminated Polyimide Resin Grafted with Carborane Nanocages: Enhanced Heat Resistance and Neutron Shielding

Resolving the barrier between low-temperature processing and extreme-environment stability in polyimide (PI) is crucial for expanding its application. In this work, a carborane hybrid thermosetting PI resin with low-temperature curing and excellent heat resistance was fabricated through a molecular hybrid design. The curing temperature of the PI hybrid resin was 329.20 °C, which was significantly lower than that of conventional phenylethynyl-terminated PI resins. The thermal resistance and compressive properties of PI hybrid resins were greatly improved, derived from high heat resistance and molecular filling of CB, yielding a hybrid resin with a glass transition temperature of 480.1 °C, compressive strength of 126.3 MPa, and exceptional thermo-oxidative stability (the temperature corresponding to 5 wt % weight loss was 557.5 °C). Meanwhile, the PI hybrid resins exhibited excellent thermal neutron shielding performance; their thermal neutron shielding efficiency reached 75.4% with a resin thickness of 5 mm. The design effectively solves the problems of PI processing property and heat resistance, and the PI hybrid resin fabricated in this work is expected to be used in nuclear reactor shielding, rocket nozzles, high-temperature electronic equipment, and hypersonic heat protection systems.