Development and thermal evolution of silver clusters in hybrid organic–inorganic sol–gel coatings

A silver doped hybrid organic–inorganic sol–gel coating was developed through the hydrolytic condensation of tetraethoxysilane (TEOS) and methyl-triethoxysilane (MTES). Silica nanoparticles were added in order to give a mechanical reinforcement and silver nitrate as the supplier of Ag+ ions, which have a potential effect as a biocide component. Synthesis of precursor sol and the evolution of silver clusters in the whole process were analyzed through Attenuated Total Reflectance Fourier Transformed Infrared spectroscopy (ATR-FTIR) and UV–visible spectroscopy. A high thermal sensitivity of sub-nanometric silver particles was determined by Small Angle X-ray Scattering (SAXS) carrying to formation of higher agglomerates or silver nanoparticles. Lixiviation tests show long-term and gradual silver releasing without worsening of the structural integrity of coatings.