Growth of Gold Crystalsunder the Presence of Bubbles Trapped under the Surface of Gold ? Poly(Vinyl Alcohol) Nanocomposite Films

Gold crystals of various morphologies have been produced by evaporating under controlled temperatures asolution of the gold-poly (vinyl alcohol) nanocomposite having entrapped hydrogen bubbles. Three-dimensional structures as well as two-dimensional dendritic gold nanostructures are formed on the different areas of the nanocomposite films. It is thought that the multitude of morphologiesis may be associated to the presence of bubbles of various shapes,entrapped under the surface of the polymer films and distorted by the confinement created by the drying films. The bubbles, through the intermediary of the over layer of poly (vinyl alcohol) film, may act as templates, providing preferential sites for nucleation of gold, confined in more and more reduced volumes, as the evaporation of the solvent advances. It is shown that the degree of super saturation of the solution, mediated by temperature, is one of the parameters determining the morphology of the growing crystals. The procedure holds promise as a new approach for the preparation of shaped gold nanoparticles.