Greatly improved thermal conductivity and electrical insulation for PVA composites via introducing functional carbon nitride nanosheets

Abstract Carbon nitride has captured much attention of researchers since it was discovered, while few studies have focused on exploring the thermal conduction applications. In this paper, carbon nitride nanosheets (CNNS) could be simultaneously functionalized during the process of exfoliation. FTIR tests proved that hydrogen bonds were constructed between PVA matrix and CNNS, at the same time, superior dispersion were also observed from SEM characterizations. In this case, significantly improved compatibility at the interfaces of them could be achieved without additional modifications. The maximum in-plane thermal conductivity of CNNS/PVA composites was enhanced to 2.7 W m−1 K−1 with low CNNS content (7.5 wt%), resulting in a sharp enhancement (785%) in comparison with that of pure PVA film (0.305 W m−1 K−1). More importantly, the as-prepared CNNS/PVA composite (at 7.5 wt% CNNS content) could even be comparable to traditional highly thermally conductive polymer composites (Graphene, Boron Nitride, Mxene, etc., were used as fillers) in terms of similar conditions. Meanwhile, the incorporation of 7.5 wt% CNNS PVA composites also showed excellent mechanical properties and electrical insulation, where the tensile strength, elongation at break, and volume resistivity reached up to 30.578 Mpa, 193.089%, 3.34 × 1011 Ω·cm respectively. These multifunctional features further indicate that CNNS/PVA composites possess the great potential for thermal management. Therefore, this work can provide effective references to prepare highly thermally conductive polymer composites by constructing in-situ functionalized CNNS, and expands its application as well.