Interfacial interaction in Ag/polymer nanocomposite films

Abstract

Metallic nanoparticles possess a wide range of novel physical properties, such as electrical, optical, magnetic properties, etc. due to their intermediate structures between atomic state and the bulk [1–3]. For example, strong third-order nonlinear optical susceptibility and ultrafast time response of noble metal (i.e. gold, silver, copper, etc.) nanoparticles have been observed around the surface plasma resonance peaks in the visible region as a result of local-field enhancement [4, 5]. From the practical point of view, these particles have to be dispersed in a solid-state matrix, made of polymers or glasses, to form nanocomposites for the purposes of gaining the necessary stability and processability for making devices [6, 7]. Noble metal nanoparticle/organic polymer composite films are of particular interest because of their potential applications for photonics and electro-optics. Polymer matrices can prevent oxidation and coalescence of the particles and provide them with a long-time stability. As a result, the specific optical and electrical properties of the nanoparticles can be brought into full play, while the typical advantages of organic polymers (e.g., elasticity, transparency, relatively simple ways of synthesis, etc.) are retained in the composite films [8– 10]. Up to now, several methods have been developed for the fabrication of nanocomposite films containing noble metal nanoparticles dispersed in polymer matrix, including in-situ formation of nanoparticles in the matrix of a polymer film, simultaneous plasma polymerization associated with metal evaporation, thermal relaxation technique, etc. [11–16]. However, performance tailoring and optimization of the nanocomposite films are limited, because the factors that affect their performance, including size, shape, microstructure, aggregated structure and concentration of nanoparticles, structure and properties of polymer matrices, and interfacial structure of composites [3, 17, 18], are difficult to be controlled simultaneously by the above approaches. In an earlier report of the authors, a simple fabrication process was developed to obtain 0–3 polymer-based silver nanocomposite films through direct mixing of polymer solution with microemlusionsynthesized silver nanoparticles [19]. It was found that nanoparticles with different geometries (e.g. sphere