Hydrogen-bond enhanced thermal energy transport at functionalized, hydrophobic and hydrophilic silica-water interfaces

In this Letter, we investigate the nanoscale heat transfer across hydrophilic silanol and hydrophobic silane interfaces. We calculate the thermal conductance at the interface via the vibrational relaxation of silica in aqueous solutions. Additionally, we directly determine the heat flux across the interface by non-equilibrium molecular dynamics. The results indicate a temperature and time dependence of the thermal conductance across the hydrophilic interface, whereas the conductance at the hydrophobic one stays constant, emphasizing the importance of hydrogen-bonded networks. Most importantly, we observe a rectifying effect of the hydrophilic silanol to the bulk substrate depending on the heat current direction. (C) 2009 Elsevier B.V. All rights reserved.