Catalyst-free sustainable epoxy vitrimers with fire safety offered by phosphorus-containing compounds

In this study, we designed and incorporated a phosphorus-rich compound, DPT, which possesses inherent catalytic properties, into a typically sustainable epoxy vitrimer. This innovative strategy enables the fabrication of flame retarded epoxy vitrimers that require no additional catalysts. DPT was synthesized through a reaction between triethanolamine (TEA) and dibenzyl chlorophosphonate (DPCP). The successful synthesis of DPT is attested to by FTIR and NMR analyses. DPT effectively accelerated the curing process of the epoxy vitrimers, yielding materials with exceptional mechanical strength and inherent self-healing abilities. Notably, the pHRR of epoxy vitrimer incorporated with DPT is reduced to 296.3 kW/m², showing a remarkable 54% reduction compared to that of the epoxy vitrimer catalyzed by conventional catalysts. The THR is also decreased from 84.3 to 42.4 MJ/m². Comprehensive analyses using cone calorimetry and TG-FTIR revealed that DPT effectively inhibits the emission of toxic gases. Crucially, the presence of DPT in the epoxy matrix facilitated the formation of a dense and stable phosphorus-laden carbon layer, which not only enhanced flame retardancy but also imparted exceptional smoke suppression capabilities. These findings underscore the potential of DPT for developing high-performance, catalyst-free, flame-retardant epoxy vitrimers.