One Component Silver-Polystyrene Nanocomposites: The Interplay of Thermoplasmonics and Elastic Mechanical Properties*

Metal-polymer nanocomposites are an interesting material class, which allows combining the superior plasmonic, electrical and thermal properties of metal-nanoparticles with the good processability of polymers. To achieve stable nanoparticles in a polymer matrix, the nanoparticle surface has to be modified with a polymer brush, which is commonly done by a ligand exchange approach.
By using Brillouin light scattering (BLS), we elucidate the nanomechanical properties of this hybrid material and combine these measurements with finite element modeling and thermography. We found a counterintuitive decrease of the speed of sound with increasing Ag content and a strong influence of the hybrid material composition. The mesoscopic order of this material can be varied drastically by thermal annealing going from a dispersed phase to a clustered state and back. Finally, the strong light absorption and thermalization of the Ag nanoparticles results in a pronounced local heating effect. Consequently, this thermoplasmonic heating can be used to change the acoustic and, therefore, mechanical properties locally.