Flame Resistant Polyurethane PolyHIPEs Stabilized with Graphene

This study introduces an approach for synthesizing polyurethane (PU) high internal phase emulsions (HIPEs) using graphene as a 2D surfactant to stabilize water-in-oil (w/o) emulsions. An emulsion sys-tem comprising a calcium chloride-saturated aqueous solution, dry acetone solution, and pristine graphite is employed to mitigate common challenges in PU HIPE fabrication, such as void formation from water-isocyanate side reactions. The resulting graphene-stabilized PU HIPEs exhibit a uniform cellular structure with tunable cell sizes dependent on graphite loading. Incorporating graphene at the emulsion interface reduces interfacial permeability and enhances the flame retardancy of the PU foams, achieving V-0 classification in UL94 vertical flammability tests. These findings demonstrate the ability to produce robust, non-flammable PU polyHIPEs with customizable architectures and broader applicability across diverse polyol systems. This work lays the groundwork for advancing lightweight, flame-resistant materials for industrial and commercial applications.