Oleo/Hydrophobic Coatings Containing Nano-Particles for the Protection of Stone Materials Having Different Porosity

Abstract

Conservation strategies to limit the degradation of stone materials are being constantly developed. To this aim, new materials are designed to confer hydrophobic properties and anti-graffiti protection to the treated surfaces. Hybrid nanocomposites, based on inorganic nano-particles added to an organic matrix, have been recently proposed for treatments of stone surfaces, obtaining promising and innovative properties. In the present paper, an experimental product based on fluorine resin containing SiO2 nano-particles, a commercial fluorine-based product and a silicon-based material were applied as protective coatings on two calcareous stones (compact and porous) widely employed in the Mediterranean region. All the studied products are expected to provide both water and anti-graffiti protection to both stones’ surfaces. The rheological characterization of the liquid products, changes in color of the surfaces, and variations in water vapor permeability allowed the compatibility of the protective systems applied to stones to be evaluated. Water–stone contact angle measurements and water absorption by capillarity were used to control the action against water ingress. The oleophobicity was assessed by measuring the oil–stone contact angle. The experimental nano-filled product proved to be a suitable hydrophobic coating for compact and porous stones; furthermore, it provides high oleophobicity to the treated surfaces, as required for anti-graffiti systems.

Towards Novel Fluorinated Methacrylic Coatings for Cultural Heritage: A Combined Polymers and Surfaces Chemistry Study

“…Vice versa, EMA_nBuMA_POMA polymer revealed to be less efficient in guaranteeing a good level of transpiration, since the RPV percentage is very close to the threshold value of 50%. Hence, also in the case of vapor permeability, the comparison with literature data, about fluorine-based polymers [48,50], underlines the goodness of the obtained results, since %RPV values are quite similar to the ones presented herein.…”

Novel Nano-Filled Coatings for the Protection of Built Heritage Stone Surfaces

“…Data about the three protective systems are reported in Table 1 . Further details about the applied products can be found elsewhere [ 19 ].…”

“…In a previous study [ 19 ], the viscosity of the used products was measured by rheological tests in steady state mode. A pseudo-plastic behavior was observed for all the investigated products and the viscosity values were similar to each other.…”

“…To provide protection against graffiti, many polymer-based coatings, displaying suitable properties (mainly oleo/hydrophobicity), have been formulated [12][13][14][15][16], but actually the anti-graffiti action needs to be proved on the particular stone material requiring protection. Biodeterioration caused by birds is another main cause of damage for stone materials in In a previous study [19], the viscosity of the used products was measured by rheological tests in steady state mode. A pseudo-plastic behavior was observed for all the investigated products and the viscosity values were similar to each other.…”

TEOS-Based Superhydrophobic Coating for the Protection of Stone-Built Cultural Heritage

“…These extreme, non-wetting properties are highly desirable for their ability to reduce the rate of water-induced degradation in natural stone. For this reason, several investigations have been carried out in the last decade to impart enhanced hydrophobicity (120 • < CA < 150 • ) [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] or, even better, superhydrophobicity (CA > 150 • ) [27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44] onto stone surfaces. However, in most of these previously published reports, nanoparticles have been used that were made of silicon [8,11,17,23,24,27,28,30,31,…”