In Situ Photochemically assisted Synthesis of Silver Nanoparticles in Polymer Matrixes

The synthesis of dispersed nanoparticles is essential for many advanced applications because of their novel properties that are greatly different from those of corresponding bulk substances. During the past years, a whole bunch of synthetic methods of metal nanoparticles (NPs) have been developed: chemical, photochemical and thermal. Amongst them, the photochemical method has attracted much attention due to it being a versatile and convenient process with distinguishing advantages such as space-selective fabrication (Sakamoto et al., 2009). This method was the key of the development of silver photography but recent advances in the chemistry of metal NPs and nanomaterials gave it a new lease of life. One of the main interests of metal NPs stems from their unique physical properties, which can be addressed by the chemical control of their shape and size (Burda et al., 2005). For instance, silver nanoparticles with spherical shape and nanometer size exhibit a very intense absorption band in the visible region due to the surface plasmon resonance. The absorption coefficient can be orders of magnitude larger than strongly absorbing organic chromophores. Besides, the enhanced electromagnetic fields generated in the closeproximity of the metal surface have a strong influence on the local environment which is illustrated by surface-enhanced Raman scattering (SERS) or by metal-enhanced fluorescence process. Nanocomposite materials combine the different properties of the components. However, in a bulk medium, the benefit of these unique performances mainly relies on the homogeneous dispersion of uniformly shaped and sized particles into the matrix. Generally, metal-polymer nanocomposites are obtained via multi-step methods. Thus, silver nanoparticles can be produced beforehand, and then dispersed into a polymerizable formulation to obtain self-assembly functionalized structures. However, besides the specific hazards related to handling dry nanoparticules, this “ex-situ” method is limited by the difficulty to control their monodispersity over a large scale (Balan et al, 2006, 2008). In the “in-situ” approach, the metal nanoparticles are generated in a polymerizable medium from cationic precursors that exhibit better dispersion ability and that undergo facile chemical or photochemical reduction. This study focuses on the in-situ synthesis of silver nanoparticles in polymer matrix through photo-assisted processes. In-situ photochemical fabrication is one of the most powerful 4