Phosphorus-containing organic-inorganic hybrid nanoparticles for the smoke suppression and flame retardancy of thermoplastic polyurethane

It is always a big challenge for fabricating flame-retarded and smoke-suppressed polymers with excellent mechanical properties in fire-safety material field. In this work, novel organic-inorganic hybrid nanoparticles named phosphoryl polyethyleneimine amide-layered double hydroxide (PPEIA-LDH) were prepared via a simple reaction process. When the PPEIA-LDH nanoparticles were used to prepare flame-retardant thermoplastic polyurethane (TPU), it was found that a small amount of PPEIA-LDH remarkably reduced the fire hazard of TPU via a typical intumescent flame-retardant mode. Only 6.0 wt% PPEIA-LDH endowed TPU with a limiting oxygen index of 29.0% and a UL-94 V-0 rating, and also reduced total smoke production and total heat release of TPU by 31.6 and 49.9%, respectively, moreover, mechanical properties of TPU did not show any decrease in this case. The analysis for flame-retardant and smoke-suppression mechanisms demonstrated that synergistic charring between the organic component and the inorganic component in PPEIA- LDH played a crucial role in reducing the fire hazard of TPU. Excellent mechanical properties of TPU/PPEIA-LDH is ascribed to the uniform dispersion of PPEIA-LDH and good interfacial interaction with TPU. This work demonstrates that organic-inorganic hybrid nanoparticle may provide a promising solution for fabricating fire-safety polymers with excellent overall performance.