Ricerc@Sapienza

The application of coating polymers to building materials is a simple and cheap way to
preserve and protect surfaces from weathering phenomena. Due to its environmentally friendly
character, waterborne coating is the most popular type of coating, and improving its performance
is an important key of research. The study presents the results regarding the mechanical and
photo-oxidation resistance of some water-based acrylic coatings containing SiO2 nanoparticles
obtained by batch miniemulsion polymerization. Coating materials have been characterized in terms
of hydrophobic/hydrophilic behavior, mechanical resistance and surface morphology by means
of water-contact angle, and scrub resistance and atomic force microscopy (AFM) measurements
depending on silica-nanoparticle content. Moreover, accelerated weathering tests were performed to
estimate the photo-oxidation resistance of the coatings. The chemical and color changes were assessed
by Fourier-transform infrared spectroscopy (FTIR) and colorimetric measurements. Furthermore,
the nanofilled coatings were applied on two different calcareous lithotypes (Lecce stone and Carrara
Marble). Its properties, such as capillary water absorption and color modification, before and after
accelerated aging tests, were assessed. The properties acquired by the addition of silica nanoparticles
in the acrylic matrix can ensure good protection against weathering of stone-based materials.