Phosphotungstate–Cyclotriphosphazene Assemblies as Multifunctional Epoxy Additives for Flame Retardancy, Mechanical Reinforcement, and Electrochemical Applications

Fire hazards pose a major challenge to wooden structures worldwide due to wood's inherent flammability and rapid flame spread, underscoring the urgent need for innovative materials and strategies to enhance fire resistance. In this context, a novel non‐covalent integration strategy was developed using pyridine‐substituted cyclotriphosphazene derivatives with Keggin‐type heteropoly tungstate anions ([PW 12 O 40 ] 3− ), yielding multifunctional POM(W)–PN‐DP, POM(W)–PN‐TP, and POM(W)–PN‐HP materials with flame‐retardant and electrochemical properties. When incorporated into epoxy and applied to wood, the 10 wt% EP/POM–PN composite achieved a UL‐94 V‐0 rating and an LOI above 24 vol%, demonstrating enhanced fire resistance and mechanical strength through a synergistic P/N effect. Cone calorimeter tests further revealed significant reductions in both the total heat release rate and peak heat release rate. The synergistic interactions among POM(W)–PN‐DP and POM(W)–PN‐HP promoted the formation of a stable protective char layer during the combustion. Furthermore, the electrochemical performance of the synthesized materials was evaluated for supercapacitor applications using a standard three‐electrode system. POM(W)–PN‐HP and POM(W)–PN‐TP showed superior performance, with specific capacitances of 227.4 and 143.2 F/g, respectively, at 1 A/g. These POM–PN hybrids represent a promising class of multifunctional additives for fire‐safe and electrochemically active polymer systems.