Formation of Gold Branched Plates in Diluted Solutions of Poly(vinylpyrrolidone) and Their Use for the Fabrication of Near-Infrared-Absorbing Films and Coatings

I. PARDIÑAS-BLANCO; C. E. HOPPE; Y. PIÑEIRO-REDONDO; M. ARTURO LÓPEZ-QUINTELA; J. RIVAS

LANGMUIR

American Chemical Society

Año: 2008 vol. 24 p. 983 - 990

0743-7463

Ribbon-like and branched gold nano- and micro-structures were produced by simple heating of diluted aqueous solutions of poly (N-vinyl-2-pyrrolidone) (PVP) and HAuCl4. The reaction was carried out in a one-pot, one-step process at mild temperatures. Modification of the synthesis variables allowed obtaining structures with different sizes and branching degrees which formed stable hydrosols with characteristic colours. A mechanism for the growth of the crystals was proposed, based on the aggregation of metal units followed by re-orientation and attachment processes facilitated by the presence of low concentrations of the polymer. These anisotropic structures were used to obtain large area porous coatings onto metallic, plastic and glass substrates and to synthesize homogeneous polymer composites. The resulting gold modified materials showed an important increase of absorption in the near infrared region of the electromagnetic spectrum, which could find interesting applications in the development of NIR absorbing filters and coatings