Fabrication of polyimide foams with superior mechanical and flame resistance properties utilizing the graft copolymerization between red phosphorus and graphene oxide

In this work, red phosphorus (RP) grafted graphene oxide (GO) was generated inside polyimide foam (PIFs) matrices using a novel method. Definite chemical interaction between RP and GO was confirmed. The RP grafted GO (GO-RP) as a beneficial additive greatly improved the mechanical, thermal and flame resistance properties of the PIFs. Scanning electron microscopy (SEM) revealed the cell size of PIFs/GO-RP minished and homogenized when compared to the pristine PIF. The mean cell diameter decreased to 0.29 mm from 0.38 mm and the open cell content was reduced by 4%. The specific strength increased greatly after adding GO-RP, from 2.14 × 10 3  N·m/kg to 2.48 × 103 N·m/kg. Besides, the pyrolysis temperature of PIFs/GO-RP shifted to a higher value and the carbon residue increased at 800 °C, indicating excellent thermal properties. The flame resistance property of foams significantly enhanced while the peak heat release rate (PHRR) was reduced by 66% compared to that of the pristine foams. The craft of PIFs/GO-RP presented here has greatly provided an potential value in the design of materials.