Carborane hybrid epoxy resins with excellent thermal stability and neutron shielding property

Abstract

The thermal resistance of epoxy resins was limited, which hindered their application in nuclear facilities. Constructing a C-B hybrid crosslinked network using carborane improved the material's thermal properties. In this study, 1, 2-dichloromethyl-o-carborane (CBCl₂) was synthesized for the first time, serving as an intermediate to synthesize N-methyl-1,3-propylenediamine-o-carborane (Et-CBNH₂) for the first time. This novel approach broadened the synthesis of carborane derivatives. Et-CBNH₂, as a curing agent, constructed a C-B hybrid crosslinked network, significantly enhancing the material's thermal resistance through mechanisms such as O-radical capture, protective layer formation, and promotion of graphitization. The material exhibited a 27.36 wt% increase under nitrogen and a 35.47 wt% increase under air in residue at 800 °C. The maximum decomposition temperature increased from 550 °C to 750 °C, with 16.59 % of the protection rate of carbon atom after thermal degradation at 750 °C in air. Furthermore, introducing the carborane structure into the networks greatly increased the glass transition temperature (T_g) by 115.58 °C. The neutron shielding properties of the material were significantly enhanced due to simultaneous enhancement of H and B atoms, which traditional methods could not achieve. This work expanded and optimized the synthesis pathway of carborane derivatives, imparting multifunctionality to epoxy resin and enhancing its various properties, thereby ensuring the safety of epoxy resin in nuclear facilities.