Interpenetrating Polymer Networks of Porous OrganicPolymers and Polyurethanes for Flame Resistance and High MechanicalProperties

We have developed an approach to simultaneously improve the fire retardancy and the mechanical strength of polyurethane (PU) elastomer through the formation of interpenetrating polymer networks (IPNs) between PU and porous organic polymer containing phosphorus and nitrogen elements (PNPOP). The PNPOP with high fire retardant ability was synthesized from hexachlorocyclotriphosphazene and 3,3′-diaminobenzidine to achieve a specific surface area of 457 m2·g−1 and a total pore volumes of 0.27 cm3·g−1. Polyester diol as the PU monomer was then impregnated into the pores of the PNPOP through diffusive process and finally PNPOP/PU composites with IPN structure were prepared by in situ polymerization. The PNPOP/PU composites possessed high thermal stability, enhanced mechanical strength and rigidity in comparison with PU sample. The fire safety of PNPOP/PU composites was greatly improved with the increase of PNPOP contents. For instance, the reduction of peak heat release rate and total heat release for the PNPOP...