Pin-point surgery of proton-deuterium substitution to enhance polybenzimidazole thermoresistances

Abstract

Thermal stability plays a crucial role in determining the polymer suitability as high-performance thermoresistant materials, which are highly demanded for lightweight substitute to metal or ceramic materials in a sustainable society. We here present an innovative approach involving the in-situ substitution of imidazole protons of polybenzimidazole (PBI) derivatives with deuterium using deuterated solvents to enhance thermal stability. The resulting substituted polymers exhibited significantly higher thermal decomposition temperatures compared to their original counterparts. This notable improvement can be attributed to the N-D bond, which possesses a low stretching frequency, demanding a greater amount of activating energy compared to the N-H bond, enabling the polymer to withstand higher temperatures. This discovery presents a novel and promising avenue for enhancing polymer thermoresistance, providing valuable insights for the development of advanced materials with enhanced thermal stability. Pinpoint surgery through in situ isotopic proton-deuterium substitution significantly enhanced the thermal degradation temperature of polybenzoxazoles, this is because N-D bond exhibit a lower stretching frequency than N-H, demanding more activating energy and thus can withstand higher temperature. This discovery provides a novel and straightforward method to elevate thermostability for polymers.