Development of silver clusters in hybrid silica based coatings through the sol-gel process

RAÚL A. PROCACCINI; MARIO APARICIO AMBRÓS; SILVIA M. CERÉ; SERGIO PELLICE

Estrasburgo

Congreso; Hybrid Materials 2011; 2011

Elsevier

The sol-gel technology makes possible the obtaining of hybrid materials with very precise characteristics according to a particular application. It brings up the possibility of functionalize materials by the introduction of different components, as inorganic salts or organic additives, inside the sol-gel structure. Consequently, functionalization of solgel materials with metallic ions or nanoparticles is worldwide and persistently explored mainly because of its optical properties. The use of silver also brings other properties of sanitary interest due to its well-known biocide activity. Ag+ has an effective action against bacteria life inhibiting their DNA replication process, increasing the permeability of the cytoplasmic membrane and inhibiting the respiratory enzymes causing asphyxia of the bacteria. A long-term biocide coating could be very useful for the development of hygienic surfaces in places such as public transports, hospitals, schools and everywhere the health of people could be exposed to bacteria-contaminated surfaces. The biocide activity of those coatings will depend, essentially, on the capability of silver to migrate through the hybrid matrix towards the surface, where the hazardous bacteria are placed. Then, the aggregation state of silver atoms takes substantial significance because of its influence on their diffusion parameters. The aim of the present work is to determine the self-organization of silver atoms inside hybrid organic-inorganic structures under different synthesis conditions and deposition parameters. In this way, two different hybrid sols, from TEOS, MTES, GPTMS and silica nanoparticles, were doped with Ag+ from its nitrate salt. Pyridine was used as silver stabilizer through formation of coordination compounds. Resulting coatings were thermally treated at different temperatures in air atmosphere. An exhaustive analysis was performed by SAXS through synchrotron light, GIXRD, XPS and UV-visible spectroscopy. Evolution of silver clusters was followed through the whole sol-gel process allowing to optimize the efficiency of the hybrid coating foreseen a long-term bactericidal effect.