Polymer-metal nanocomposite thin films fabricated by a sputter-anneal process and relevance of the polymer matrix

Polymer-metal nanocomposite thin films are versatile materials that exploit the mutualistic impact of the unique attributes of the polymer and metal nanoparticle components, enabling applications in various areas including photonics, sensing and catalysis. Sputtering followed by thermal annealing can produce metal or semiconductor nanoparticle thin films on suitable substrates. We present an optimized protocol for the fabrication of polymer-metal nanocomposite thin films, involving spin-coating of the polymer (poly(vinyl alcohol), polyaniline) film and the sputter-anneal process to form metal (silver) nanoparticles in the polymer matrix. Silver nanoparticle films and the polymer-silver nanocomposite films fabricated are characterized using UV-visible spectroscopy, electron microscopy and X-ray photoelectron spectroscopy. The polymer thin film influences significantly, the size and distribution of the nanoparticles formed within. Poly(vinyl alcohol) film is found to enable the formation of a uniform distribution of relatively small silver nanoparticles, with the annealing carried out at lower temperatures than that commonly used in the sputter-anneal procedure. Significantly, mild oxidation of the bare silver nanoparticles that occur during the annealing process is inhibited by the polymer environment. The nanocomposite formation is shown to bestow stability on the nanoparticles, against aggregation under external stimuli like the electron beam, and temporal changes under ambient atmosphere. Synopsis: Ag-polymer nanocomposite thin films are fabricated by the sputter-anneal process and the specific utility of the polymer matrix in the formation of uniform distribution and stabilization of the small nanoparticles demonstrated.