Phosphorus-nitrogen Flame Retardant Waterborne Polyurethane/Graphene Nanocomposite for Leather Retanning

We demonstrate a facile and green approach to prepare phosphorus-nitrogen containing waterborne polyurethane/graphene nanocomposite (PN/G-WPU) as flame-retardant retanning agent for leather. The PN/G-WPU was synthesized by covalently embedding phosphoramidate-based diol into polyurethane chain, followed by emulsification with graphene oxide (GO) aqueous solution and in-situ reduced with hydrazine hydrate. The structure and emulsion stability of prepared PN/GWPU were characterized, and the physical mechanical properties as well as the flammability of resulting leathers were investigated. The results indicate the good dispersion and strong interfacial interaction of graphene with polyurethane matrix, which facilitates the PN/G-WPU penetrating into leather fibers. The PN/G-WPU retanning agent can effectively improve the comprehensive performance of resultant leather such as hydrothermal stability, physical-mechanical properties, flame retardancy and smoke suppression performance. Accordingly, our method might provide an alternative strategy for manufacturing high-performance leather.