Flexible Graphene Nanocomposites with Simultaneous Highly Anisotropic Thermal and Electrical Conductivities Prepared by Engineered Graphene with Flat Morphology.

Achieving nanocomposites with simultaneous highly anisotropic thermal and electrical conductivities using carbon materials remains challenging as carbon material tends to form random networks in nanocomposites. Here, highly anisotropic and flexible graphene@naphthalenesulfonate (NS)/poly(vinyl alcohol) (GN/PVA) nanocomposites were fabricated using a layer-by-layer scraping method with flat graphene as the starting functional filler. NS acted as a bond bridge for linking the graphene (π-π interaction) and PVA (hydrogen bond). The results showed well-dispersed graphene in the nanocomposites while maintaining flat morphology with uniform in-plane orientation. The as-fabricated nanocomposites exhibited highly anisotropic thermal and electrical conductivities. The in-plane and out-of-plane thermal conductivities of the nanocomposite prepared with 10.0 wt % graphene reached 13.8 and 0.6 W m-1 K-1, and in-plane and out-of-plane electrical conductivities were 10-1 and 10-10 S cm-1, respectively. This indicated highly anisotropic thermal and electrical conductivities. Furthermore, the nanocomposites showed elevated flexibility and tensile strength from 42.0 MPa for pure PVA to 110.0 MPa for GN-5.0 wt %/PVA. In sum, the proposed strategy is effective for the preparation of nanocomposites with high flexibility, as well as superior anisotropic thermal and electrical conductivities.