Scalable monolayer-functionalized nanointerface for thermal conductivity enhancement in copper/diamond composite.

Aiming at developing high thermal conductivity copper/diamond composite, an unconventional approach applying self-assembled monolayer (SAM) prior to the high-temperature sintering of copper/diamond composite was utilized to enhance the thermal boundary conductance (TBC) between copper and diamond. The enhancement was first systematically confirmed on a model interface system by detailed SAM morphology characterization and TBC measurements. TBC significantly depends on the SAM coverage and ordering, and the formation of high-quality SAM promoted the TBC to 73 MW/m2-K from 27 MW/m2-K, the value without SAM. With the help of molecular dynamics simulations, the TBC enhancement was identified to be determined by the number of SAM bridges and the overlap of vibrational density of states. The diamond particles of 210 μm in size were simultaneously functionalized by SAM with the condition giving the highest TBC in the model system and sintered together with the copper to fabricate isotropic copper/diamond composite of 50% volume fraction. The measured thermal conductivity marked 711 W/m-K at room temperature, the highest value among the ones with similar diamond-particles volume fraction and size. This work demonstrates a novel strategy to enhance the thermal conductivity of composite materials by SAM functionalization. The precisely-controlled scalable nanointerface by the organic monolayer was firstly implemented in the fabrication of pronounced high thermal conductive composite through the high-temperature plasma sintering process. Image 1 • Self-assembled monolayer is firstly applied in the fabrication of high thermal conductive composite material by sintering. • The number of chains and the phonon transmission via each chain molecule determines the interfacial thermal conductance. • The nanointerface with extensive area in the composite can be precisely controlled by the scalable experimental process. • A marked thermal conductivity is realized for the copper/diamond composite. [ABSTRACT FROM AUTHOR]