Metal complexes with endothermic properties (phase transition, cold crystallisation) could provide new FR solutions. This theory mini-review considers how certain metal complexes, which modify at lower temperatures than necessary for polymer ignition and absorb heat (endothermic) may provide new flame-retardant mechanisms. Heat absorption may be by modification of the crystal shape of the metal complex, or by cold crystallisation (endothermic dissolution in a form of supercooling with latent heat storage). To date research is at the theoretical stage, based on some examples of molecules known to exhibit such behaviour in other applications.
“Toward Flame Retardants or Thermal Stabilizers with New Mechanism for Polymers”, T. Akitsu et al., FirePhysChem (2023), https://doi.org/10.1016/j.fpc.2023.03.004