  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/m^2-K from 27 MW/m^2-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
{\micro\metre} 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.
