Phosphorus-containing curing agents with dynamic bonds endowing epoxy resins with flame retardancy and remolding capability

To prepare epoxy resins (EP) with flame retardancy and remolding capability, novel amine curing agents (DDPM and DDPS), which incorporate phosphonates and bis-Schiff bases, were used to replace DDM partially or completely for EP curing. Curing kinetics based on a dual-parameter autocatalytic model showed that DDPM and DDPS had higher reactivity of than DDM. EP/DDPM and EP/DDPS vitrimers demonstrated excellent flame retardancy and remolding capability (up to 60.8%). EP/DDPS with disulfide bonds could not effectively improve the dynamic bond exchange. The molecular weight, dynamic bond stability, and viscosity were analyzed to investigate the underlying mechanisms. This study endows the dynamic properties of EP using novel curing agents and achieves flame-retardant and sustainable epoxy thermosets.