In situ synthesis of high-density contact-free Ag-nanoparticles for plasmon resonance polystyrene nanocomposites

The fabrication of plasmonic Ag-nanocomposites (PMN) by a high energy-transfer thermal degradation of Ag-acac was reported. Commercial Ag-acac was used to synthesize silver nanoparticles in molten PS. The silver precursor, available in crystalline powder form, was first dissolved in chloroform and then the amorphous polystyrene was added in pellets to the solution. The suspensions obtained in this way were then cast into petri dishes to form films of the same thickness and dried in air at 25°C for several hours to let the solvent fully evaporate. Then, all the samples were thermally annealed on a hot-plate at a constant temperature of 200°C. Before annealing the samples, the thermolysis reaction of the precursor was studied in the presence of air and within the PS matrix to identify the optimal process temperature and duration. The process conditions found guarantee the synthesis of contact-free nanoparticles of size smaller than 40 nm, key element to obtain a single and narrow SPR, and a limited scattering over the whole visible spectrum.