Flame Retardant and Anticorrosion Epoxy Resin with High Flame Retardancy and Toughness Enabled by P/N Ionic Compound

In order to achieve high-performance epoxy resin (EP) materials with superior flame retardancy, smoke suppression, transparency, and strong mechanical properties, an ionic compound (DD) was prepared via a straightforward acid/base-neutralization reaction, with its structural accuracy verified through multiple characterization methods and density functional theory calculations. This compound was then utilized as a flame retardant in EP. The resultant EP/DD composite exhibited significant enhancements in flame retardancy, with the limiting oxygen index reaching up to 37.2% at the maximum, while showing substantial reductions of 31.0% in total smoke production and 42.2% in total heat release when benchmarked against neat EP. The enhanced flame-retardant performance of the EP/DD composite is mainly due to DD’s ability to capture free radicals and its highly effective catalytic carbonization mechanism. Moreover, the EP/5DD composite exhibited exceptional mechanical performance, with tensile and flexural strength increases of 58.1 and 79.8%, respectively, over pure EP. Significantly, the flexural toughness exhibited a substantial enhancement of 259.1%, a level that is seldom observed in modified EPs documented in the literature. Additionally, the EP composite retained corrosion resistance and excellent transparency. These outstanding properties underscore the potential of EP/DD composites to expand the application scope of EP materials.