Highly anisotropic thermal conductivity and electrical insulation of nanofibrillated cellulose/AlO@rGO composite films: effect of the particle size.

Nanofibrillated cellulose (NFC) film has received tremendous attention due to its excellent electrical insulation, which shows great application prospects in the field of electronic devices. However, the low efficient heat dissipation of NFC film largely limits its use in advanced applications. In this work, the reduced graphene oxide hybrid fillers loaded alumina (AlO) particles with different sizes were synthesized by different drying methods, and then they were mixed with NFC to prepare a series of NFC-based composite films. The effect of AlOparticle sizes on the thermal conductivity of NFC-based composite films was studied. The results showed that the surface areas of l-AlOparticles were smaller than that of s-AlOparticles, resulting in the smaller interface thermal resistance and superior thermal conductivity of the film containing l-AlOparticles. The NFC-based composite films showed great potential for applications in thermal management by adjusting the particle size of fillers.