Silicon nanoparticle decorated graphene composites: preparation and their reinforcement on the fire safety and mechanical properties of polyurea

Reduced graphene oxide (rGO) was decorated with organic/inorganic nanoparticles through an in situ sol-gel process with various thicknesses. The presence of organic/inorganic nanoparticles made the rGO lipophilic, as evidenced by the good dispersion of the nanoparticles-rGO in dimethyl formamide solvent (DMF). The thickness of the nanoparticles-rGO could be varied by adjusting the amount of the silicane additive, as evidenced by the AFM results. The nanoparticles-rGO was then incorporated into polyurea in different ratios via in situ polymerization and the property enhancement of the nanocomposites was investigated. The TEM morphological study showed that, due to the good interfacial interaction between the nanoparticles-rGO and polyurea, nanoparticles-rGO was dispersed well in the polyurea matrix. Compared with the rGO, the nanoparticles could significantly improve the thermal stability and thermal conductivity of polyurea, implying that the good dispersion of rGO and the functional groups on the surface of rGO had a significant effect on the thermal stability and thermal conductivity of polyurea. The peak heat release rate (pHRR) of nanoparticles-rGO/polyurea nanocomposites was significantly reduced, which indicated that the combustible gas releasing rate of polyurea was reduced. Moreover, the storage modulus and tensile strength of the nanocomposites with 0.2 wt% have been enhanced by about 60% and 110% in comparison with those of neat polyurea, respectively. This simple and effective approach, decorating the rGO with organic/inorganic nanoparticles, is believed to offer possibilities for broadening the graphene applications in the polymer materials and make it possible to decorate the graphene with other functional groups and vary the aspect ratio of decorated graphene according to its application.