Fabrication of Lignin-Based Nano Carbon Film-Copper Foil Composite with Enhanced Thermal Conductivity

Technical lignin from pulping, an aromatic polymer with ~59% carbon content, was employed to develop novel lignin-based nano carbon thin film (LCF)-copper foil composite films for thermal management applications. A highly graphitized, nanoscale LCF (~80-100 nm in thickness) was successfully deposited on both sides of copper foil by spin coating followed by annealing treatment at 1000 °C in an argon atmosphere. The conditions of annealing significantly impacted the morphology and graphitization of LCF and the thermal conductivity of LCF-copper foil composite films. The LCF-modified copper foil exhibited an enhanced thermal conductivity of 478 W m^-1 K^-1 at 333 K, which was 43% higher than the copper foil counterpart. The enhanced thermal conductivity of the composite films compared with that of the copper foil was characterized by thermal infrared imaging. The thermal properties of the copper foil enhanced by LCF reveals its potential applications in the thermal management of advanced electronic products and highlights the potential high-value utility of lignin, the waste of pulping.