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The reduction of graphite oxide (GO) in the presence of reactive poly(methyl methacrylate) (PMMA), under mild biphasic conditions, directly affords graphene grafted with PMMA. The resulting nanocomposite shows excellent electrical conductivities resulting from the optimal dispersion and exfoliation of graphene in the polymer matrix.

Rigid polyurethane (PU) nanocomposite foams filled with multi-walled carbon nanotubes (MWCNTs), functionalized MWCNTs (f-MWCNTs) and functionalized graphene sheets (FGS) were synthesized by reactive foaming to obtain electromagnetic interference (EMI) shielding materials. Our study indicates that the electrical properties of rigid PU nanocomposite foams are strongly dependent on the foaming evolution, cellular structure and density of these materials, which are themself influenced by the morphology, aspect ratio and surface functionalization of the carbon-based nanofillers. The largest EMI shielding effectiveness was obtained for 0.35 wt% MWCNTs with an electrical conductivity increased of two orders of magnitude ascribed to the formation of a better interconnected network within the systems.

Flexible polyurethane foams filled with a fixed amount of carbon-based nanofillers, in particular multiwall nanotubes and graphenes, have been studied to clarify the influence of the morphology and functional groups on the physical properties of these polymeric foams. The effect of the carbon nanoparticles on the microphase separation has been analyzed by FT-IR spectroscopy revealing a decrease in the degree of phase separation of the segments. Variations of the glass transition temperature and an improved thermal stability were observed due to the presence of the nanoparticles. The EMI shielding effectiveness of flexible PU foams has also been enhanced, in particular for FGS nanocomposite foams.