Flame-retardant vegetable oil-based rigid polyurethane foam constructed with Mxene@HNT and hydrogel via layer-by-layer coating

Abstract

Rigid polyurethane foam (RPUF) meets the demand for green environmental protection by utilizing vegetable oil as polyol. However, enhancing its flame retardancy is essential to address safety concerns for its widespread application across various commercial sectors. In this work, we successfully prepared Mxene@HNT, and then employed a layer-by-layer coating to immobilize Mxene@HNT onto RPUF surfaces using dual hydrogel (DH), thus creating the RPUF/M@H/DH flame retardant system. Comparative analysis against standard RPUF demonstrates significant enhancements in flame retardancy, achieving a ``V-0'' rating in the UL-94 vertical combustion test, with a limiting oxygen index (LOI) of 30.5 %. Notably, in cone calorimetry test (CCT), peak heat release rates (pHRR) and peak smoke production rates (pSPR) were reduced by 29.34 % and 14.95 % respectively for RPUF/M@H-3/DH, while experiencing a 151.5 % increase in carbonization yield (CY) compared to standard RPUF. Importantly, the mechanical properties of RPUF maintained well upon surface modification to obtain flame retardant RPUF/M@H/DH. Thus, this study offers a novel perspective on addressing both environmental concerns and flame retardancy requirements for RPUF.