Smart hybrid coatings for cultural heritage

Abstract

The protection of stone monuments against deterioration has recently attracted much attention from scientists. An accurate analysis of the degradation mechanisms of stones has led to the conclusion about the necessity of protection especially against the condensed water and the salts formation. In this study the strengthening effect of nanoparticles-based treatments applied on marbles surfaces is compared to that exhibited by silane commercial polymers. The surface properties of these types of smart coatings were investigated by different analytical techniques such as contact angle measurements, to gain information on surface hydrophobicity and super-hydrophobicity, and Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray Spectroscopy (EDS), to characterize the surfaces morphology. Aimed at evaluating the superior performance of hybrid coatings , exposure tests both to UV ageing and to atmospheric pollution in a highly polluted typical urban environment, were carried out. Furthermore both bare and coated samples were submitted to aging tests in a Q-UV tester cabinet (1000 h of exposure to UV radiation). Diffuse Reflectance Spectroscopy (DRS) was employed for the CIELab colorimetric coordinates assessment, while Ion Chromatography (IC) was employed to evaluate the coating capacity to avoid salts (Cl-, NO3- and SO42-) formation. Water vapour permeability and water absorption by capillarity were also evaluated