Web Release Date: February 1,
Thermal Transport in Au-Core Polymer-Shell Nanoparticles
and
Department of Materials Science and Engineering, the Frederick Seitz Materials Research Laboratory, and the Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana, Illinois 61801, and Department of Chemistry, University of Minnesota, 207 Pleasant St SE, Minneapolis, Minnesota 55455
Received December 12, 2004
Revised January 19, 2005
Abstract:
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. The threshold concentration of cosolvent that creates the changes in thermal conductivity, 5 vol % tetrahydrofuran in water or 40 vol % N,N-dimethylformamide in water, is identical to the threshold concentrations for producing small shifts in the frequency of the plasmon resonance. Because the maximum fraction of solvent in the polymer shell is less than 20 vol %, the increase in the effective thermal conductivity of the shell cannot be easily explained by contributions to heat transport by the solvent or enhanced alignment of the polystyrene backbone along the radial direction.
Download the full text: PDF | HTML
