How Does van der Waals Confinement Enhance Phonon Transport?

We study the mechanism of van der Waals (vdW) interactions on phonon transport in atomic scale, which would boost developments in heat management and energy conversion. Commonly, the vdW interactions are regarded as a hindrance in phonon transport. Here we propose that the vdW confinement can enhance phonon transport. Through molecular dynamics simulations, it is realized that the vdW confinement is able to make more than two-fold enhancement on thermal conductivity of both polyethylene single chain and graphene nanoribbon. The quantitative analyses of morphology, local vdW potential energy and dynamical properties are carried out to reveal the underlying physical mechanism. It is found that the confined vdW potential barriers reduce the atomic thermal displacement magnitudes, leading to less phonon scattering and facilitating thermal transport. Our study offers a new strategy to modulate the phonon transport. (express letter)