Persistently flame-retardant flexible polyurethane foams by a novel phosphorus-containing polyol

To overcome the poor compatibility, easy migration of additive flame retardants, a novel polyester polyol (DMOP) was synthesized from dimethyl methylphosphonate and diethanol amine through transesterification and used in the foaming formula to prepare inherent flame-retardant flexible polyurethane foams (FPUFs). DMOP mainly play soft segments in the foams which increases the flexibility and elongation at break. With a low incorporation amount of 10 php (ca. 6.3 wt%), the resultant FPUF can pass vertical burning test. More importantly, accelerated ageing tests at 140 °C for 64 h indicate the persistent flame retardancy of DMOP for FPUF. The thermogravimetric analysis (TGA) results reveal their lower thermal stability than that of ordinary polyurethane. The corresponding flame-retardant mechanism of DMOP-containing FPUFs is investigated by Pyrolysis gas chromatography and mass spectrometry (Py-GC/MS) and FTIR, which indicates the phosphorus in DMOP mainly played their role in the vapor phase. This work thus offers a facile route for preparing FPUFs with persistent, efficient flame retardancy.