Intrinsic temperature dependence of plasmonic resonances in gold nanorod polymer nanocomposites*

Optical scattering in plasmonic polymer nanocomposites is strongly influenced by the dielectric properties of both matrix and particles. Since changes in temperature can affect each constituent in fundamentally different ways, interpretation of optical scattering spectra as a function of temperature is not straightforward. Here we present a systematic experimental and analytical study of the optical scattering of gold nanorods embedded in an epoxy matrix. We demonstrate that the temperature dependence of scattering spectra from gold-polymer nanocomposites depends on the relative thickness of the surrounding ligands or inorganic coatings that are typically used to stabilize nanorods in polymer matrices. Using empirical fits for the dielectric functions of gold, epoxy, and coating materials we show that it is possible to correct for temperature effects in the interpretation of scattering spectra. This can greatly enhance the precision and accuracy of material state sensing applications that rely on the plasmonic response of gold nanorods in polymers.