Thermal conductance of hydrophilic and hydrophobic interfaces.

Using time-domain thermoreflectance, we have measured the transport of thermally excited vibrational energy across planar interfaces between water and solids that have been chemically functionalized with a self-assembled monolayer (SAM). The Kapitza length--i.e.

Thermal transport in au-core polymer-shell nanoparticles.

Thermal transport in aqueous suspensions of Au-core polymer-shell nanoparticles is investigated by time-resolved measurements of optical absorption. The addition of an organic cosolvent to the suspension causes the polystyrene component of the polymer shell to swell, and this change in the microstructure of the shell increases the effective thermal conductivity of the shell by a factor of approximately 2. The corresponding time scale for the cooling of the nanoparticle decreases from 200 ps to approximately 100 ps.