Superhydrophobic Coatings Based on Siloxane Resin and Calcium Hydroxide Nanoparticles for Marble Protection
1
Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
2
Department of Management and Conservation of Ecclesiastical Cultural Heritage Objects, University Ecclesiastical Academy of Thessaloniki, 54250 Thessaloniki, Greece
*
Author to whom correspondence should be addressed.
Coatings 2020, 10(4), 334; https://doi.org/10.3390/coatings10040334
Received: 12 March 2020 / Revised: 25 March 2020 / Accepted: 27 March 2020 / Published: 1 April 2020
(This article belongs to the Special Issue Water and Oil Repellent Surfaces)
Calcium hydroxide (Ca(OH2)) nanoparticles are produced following an easy, ion exchange process. The produced nanoparticles are characterized using transmission electron microscopy (TEM) and Fourier- transform infrared spectroscopy (FTIR) and are then dispersed in an aqueous emulsion of silanes/siloxanes. The dispersions are sprayed on marble and the surface structures of the deposited coatings are revealed using scanning electron microscopy (SEM). By adjusting the nanoparticle concentration, the coated marble obtains superhydrophobic and water repellent properties, as evidenced by the high static contact angles of water drops (> 150°) and the low sliding angles (< 10°). Because Ca(OH)2 is chemically compatible with limestone-like rocks, which are the most common stones found in buildings and objects of the cultural heritage, the produced composite coatings have the potential to be used for conservation purposes. For comparison, the wetting properties of another superhydrophobic and water repellent coating composed of the same siloxane material and silica (SiO2) nanoparticles, which were commonly used in several previously published reports, were investigated. The suggested siloxane+Ca(OH)2 composite coating offers good protection against water penetration by capillarity and has a small effect on the aesthetic appearance of marble, according to colorimetric measurements.
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Keywords:
superhydrophobic; water repellency; calcium hydroxide; siloxane; marble; cultural heritage; conservation
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MDPI and ACS Style
Chatzigrigoriou, A.; Karapanagiotis, I.; Poulios, I. Superhydrophobic Coatings Based on Siloxane Resin and Calcium Hydroxide Nanoparticles for Marble Protection. Coatings 2020, 10, 334. https://doi.org/10.3390/coatings10040334
AMA Style
Chatzigrigoriou A, Karapanagiotis I, Poulios I. Superhydrophobic Coatings Based on Siloxane Resin and Calcium Hydroxide Nanoparticles for Marble Protection. Coatings. 2020; 10(4):334. https://doi.org/10.3390/coatings10040334
Chicago/Turabian StyleChatzigrigoriou, Aikaterini; Karapanagiotis, Ioannis; Poulios, Ioannis. 2020. "Superhydrophobic Coatings Based on Siloxane Resin and Calcium Hydroxide Nanoparticles for Marble Protection" Coatings 10, no. 4: 334. https://doi.org/10.3390/coatings10040334
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