Poly(methyl methacrylate)-vapor growth carbon fiber-graphene nanocomposites prepared using supercritical CO2 mixing and drying

•scCO2 mixing is superior to NMP mixing for dispersing VGCFs and GNPs in an PMMA.•Synergistic effect is observed for electrical and thermal conductivities.•Volumetric expansion of the solution was clearly demonstrated under scCO2 condition.•The residual NMP in the nanocomposites was completely removed through scCO2 drying.

Supercritical carbon dioxide (scCO2) has been employed in conjunction with vapor growth carbon fibers (VGCFs) and graphene nanoplatelets (GNPs) to enhance the properties (electrical, thermal, physical) of a poly(methyl methacrylate) (PMMA) matrix. When the VGCF loading was 10 wt.%, the electrical conductivity (9.33 S/m) of the PMMA-VGCF nanocomposite prepared through scCO2 mixing at 103.4 bar and 40 °C was 15.6% greater than that obtained when using traditional mixing in N-methyl-2-pyrollidone (NMP). A synergetic effect existed for the VGCFs and GNPs, with the thermal conductivity of the PMMA-VGCF-GNP nanocomposite [0.492 W/(m K)] being 20.2% greater than that of the individual PMMA-VGCF nanocomposite [0.409 W/(m K)], after applying scCO2 mixing. The advantages of the proposed scCO2 technology are twofold: it enhances the dispersion of VGCFs and GNPs in the PMMA matrix and eliminates residual NMP after scCO2 drying.

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