Enhanced Thermal Conductivity of Bioinspired Nanofibrillated Cellulose Hybrid Films Based on Graphene Sheets and Nanodiamonds

Polymer materials with high thermal conductivities play an important role in the development of next-generation electronics. In this work, high thermally conductive nanofibrillated cellulose (NFC) hybrid films based on nanodiamonds (NDs) and graphene sheets (GSs) were prepared by a facile vacuum-filtration self-assembly process. Inspired by the structure of nacre, zero-dimensional NDs, two-dimensional GSs, and one-dimensional NFC were used to build hierarchical structures, which lead to excellent mechanical properties of the hybrid films. More importantly, an efficient thermally conductive pathway, involving NDs and GSs, endows the hybrid films with a much higher in-plane thermal conductivity. At a filler content of 10 wt %, the in-plane thermal conductivity of the f-C/ND/G hybrid film could reach 14.35 W·m–1·K–1, which is at a high level compared with other published studies. This hybrid film exhibits significant thermal conductivity combined with excellent mechanical properties that can be applied to portable electronic equipment as a lateral heat spreader.