A facile strategy for synthesizing hyperbranched phosphorus-containing polyol: Toward enhancing intrinsic flame retardancy and smoke suppression of rigid polyurethane foams

Rigid polyurethane foams (RPUFs) are critically challenged by their inherent high flammability and the generation of toxic smoke. In this study, we synthesized a novel, easily manufacturable hyperbranched phosphorus-containing polyol, named HPEAP. The RPUF composites containing 50 wt% HPEAP exhibited exceptional performance, notably in reducing flammability and enhancing flame retardancy. Compared to traditional RPUF and brominated RPUF, the composites with 50 wt% HPEAP showed significant reductions in peak heat release rate (65.56%) and total heat release (72.38%). It is noteworthy that phosphorus-based flame retardants typically have the drawback of increasing smoke production. However, the addition of 50 wt% HPEAP significantly reduced the total smoke production of RPUF by 66.34%, overcoming a common limitation. This performance is largely attributed to the excellent thermal stability of HPEAP and its ability to promote a super high char yield. In summary, this work presents a straightforward approach for manufacturing high-performance RPUF products with enhanced fire safety characteristics, showcasing HPEAP's potential to improve the environmental and safety profiles of polyurethane foams.