Thermal insulation, flame retardancy, smoke suppression, and reinforcement of rigid polyurethane foam enabled by incorporating a P/Cu-hybrid silica aerogel

The frequent occurrence of fires caused by rigid polyurethane foam highlights the importance of its fire safety, however, the existing flame-retardant methods often seriously deteriorate the mechanical properties and thermal insulation of the foam. Here, we demonstrate a new idea for thermal insulation, flame retardancy, smoke suppression, and reinforcement of polyurethane foams only by incorporating a P/Cu-hybrid silica aerogel. This unique aerogel combines with the carbon-promoting action of P, catalytic attenuation of Cu, and the barrier effect of aerogels, thus leading to high smoke-suppressing and flame-retardant efficiency for polyurethane foam. At a low addition amount of 5 wt% aerogel, the total heat release, peak heat release rate, total smoke release, and toxic CO production of the composite foam are all significantly reduced. Interestingly, the aerogel-containing composite foam exhibits a special hierarchical porous structure, which enables lower thermal conductivity and higher thermal insulation than pure RPUF. Benefitting from the good compatibility and nano-enhancing effect of the aerogel, the compressive strength of the composite foam remarkable increase of 52.2%. This research offers an effective method for designing high-performance foam materials with high fire safety and low thermal conductivity, which has broad application prospects in the field of thermal insulation.