Assessment of waterborne coatings formulated with sol-gel/Ag related to fungal growth resistance

Abstract

Fungal growth in damp surfaces of water-damaged buildings is an increasing problem around the world, which has adverse effects on both people's health and buildings. By bio-deterioration, fungi can growth in indoor environments and generate materials losses in addition to health problems. Therefore, antifungal coatings must be developed to avoid these problems. Silica is used as supporting additive in coatings, such as the waterborne paints and, on the other hand, the addition of Ag nanoparticles into different materials is being widely studied for its effective antimicrobial properties. The aim of this work was to evaluate the bio-resistance to fungal growth on waterborne coatings containing siliceous additives, by accelerated four-week agar plate assay. The additives were synthesized by the sol-gel method and characterized by potentiometric titration and transmission electron microscopy (TEM). In addition, the paints were observed by scanning electron microscopy (SEM) at the end of the test. To carry out the bioresistance assay, Chaetomium globosum and Alternaria alternata fungi were used. After 4 weeks of assay, paints prepared with the silver-additives were the most efficient inhibiting the growth of both fungi. These paints, after their exposure for 6 months, in an internal environment with sunlight incidence, kept the antifungal activity against Chaetomium globosum and showed a higher activity against Alternaria alternata.