Highly Thermally Conductive Composite Films Based on Nanofibrillated Cellulose in Situ Coated with a Small Amount of Silver Nanoparticles

In this paper, a freestanding flexible nanofibrillated cellulose (NFC)/silver (Ag) composite film with high thermal conductivity (TC) was prepared using the NFC that was in situ coated with a small amount of Ag nanoparticles through mussel-inspired chemistry of dopamine. The results demonstrated that Ag nanoparticles were homogeneously coated on the surface of NFC nanofibers and their incorporation had little influence on the film-forming ability of NFC. The NFC decorated with Ag nanoparticles could easily form thermally conductive pathways in the composite films, and the resultant films containing only 2.0 vol % of Ag showed a high in-plane TC value of 6.0 W/(m·K), which was 4 times that of pure NFC film. Moreover, the composite films exhibited relatively high strength and flexibility. The highly thermally conductive NFC/Ag composite films possess potential applications as lateral heat spreaders in flexible electronic equipment

Highly in-Plane Thermally Conductive Composite Films from Hexagonal Boron Nitride Microplatelets Assembled with Graphene Oxide

With the development of portable and flexible devices, demands for high-performance thermal management materials with high in-plane thermal conductivity (TC), mechanical flexibility, and electrical insulation are growing. Hexagonal boron nitride (BN) is a promising thermally conductive filler due to its high in-plane TC and electrical insulation. In this work, taking full advantage of good film-forming feature of graphene oxide (GO) suspension and its ability to stably disperse BN microplatelets (BNMPs) in the aqueous medium, the GO/BNMPs composite films with high in-plane TCs were prepared by a simple cast-drying method. The structure characterization demonstrated that GO can induce BNMPs to preferably arrange in-plane orientation in the composite films. The resultant composite films possessed a maximum in-plane TC value of 10.3 W/m·K at 50 wt % BNMPs. Moreover, the films exhibited excellent mechanical flexibility and satisfactory electrical insulation. The proposed method of fabricating BNMPs-based composite films in this work is facile handling, eco-friendly, and suitable for large-scale production, and it therefore enables potential applications in flexible electronics