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

Excerpt

In the last decades, polymer matrix nanocomposites (PMN) have been studied extensively to exploit the properties of nanofillers for transforming the nature of practical household materials, in particular for mechanical properties [1]. Despite the early successes [2], the massive interest in nanocomposites started in 1990s, when Toyota proved that adding mica to nylon produced a fivefold increase in the yield and tensile strength of the matrix material [3, 4]. Subsequent developments further contributed to the surging interest in polymer–nanoparticle composites. In particular, the growing availability of nanoparticles of monodispersed size and shape, such as fullerenes, carbon nanotubes, inorganic nanoparticles, dendrimers, and bionanoparticles, and the refining of instrumentation to probe nano-objects, such as scanning force, laser scanning fluorescence, and electron microscopes, have spurred research aimed at probing the influence of particle size and shape on the properties of PMN also for functional applications: optics, photonics, catalysis, electronic devices, and Microsystems [5, 6]. A sub-class of PMN is represented by the metal–polymer nanocomposites (hereinafter MPN) which directly harness the fundamental properties of metal nanoparticles when embedded in a polymer matrix. There is a widespread interest in this material class especially for the optical and photonic fields uses including: eye and sensor protection [7], optical communications [8], optical information processing [9], Raman enhancement materials [10], optical switching [11, 12], plasmon waveguides [13, 14], light stable colour filters [15, 16], polarisers [17], and modified refractive index materials [18]. Particularly, for all the applications mentioned above, the spectroscopy properties of silver nanoparticles are extremely useful; therefore, Ag-nanoparticles have been extensively modelled [19] and characterized when suspended in liquid media [20, 21]. Depending on the particle diameters and the surrounding medium the Ag-based colloids exhibit narrow and intense surface plasmon resonance (SPR) displaying selective absorption of visible radiation which are found suitable to develop a novel class of optical limiters and filters. In fact, it is generally acknowledged that the optical excitation of plasmon resonances in nanosized Ag particles is the most efficient mechanism by which light interacts with matter—a single Ag nanoparticle interacts with light more efficiently than a particle of the same size of any known chromophore. Silver is also the only material whose plasmon resonance can be tailored to any wavelength in the visible spectrum [22]. For all these reasons, in this study, silver was chosen as a nanofiller to develop a novel class of SPR material to be employed in a number of automotive components such as optical filtering glasses and micro-optical-electro-mechanical systems (MOEMS). …