Thermal preparation and stabilization of crystalline silver particles in SiO2-based coating solutions

Ag/SiO2 coating solutions for antimicrobial functionalisation can be prepared by a thermal reaction (reflux or solvothermal conditions) of mixtures of tetraethoxysilane, alkylamine compounds and AgNO3. These coating solutions are especially useful for antimicrobial refinement of temperature sensitive materials like textiles or wood. Moreover coating application onto substrates such as glass or metal, as well as preparation of micrometer sized bulk particles by using a spray-drying process is also feasible. The efficiencies of AgNO3 reduction in the presence of different amine compounds like triethanolamine, triethylamine or diethanolamine are compared. SiO2 nanoparticles are formed by basic hydrolysis of tetraethoxysilane and stabilize the crystalline silver particles in the solution. The antimicrobial effect of silver containing coatings on textile fabrics is investigated.