Waterborne Superhydrophobic and Superoleophobic Coatings for the Protection of Marble and Sandstone

Abstract

Silica nanoparticles were dispersed in an aqueous emulsion of alkoxy silanes and organic fluoropolymer. The dispersion was sprayed onto white marble and sandstone. The deposited composite coatings exhibited (i) superhydrophobicity and superoleophobicity, as evidenced by the high (>150°) static contact angles of water and oil drops as well as (ii) water and oil repellency according to the low (<7°) corresponding tilt contact angles. Apart from marble and sandstone, the coatings with extreme wetting properties were deposited onto concrete, silk, and paper, thus demonstrating the versatility of the method. The siloxane/fluoropolymer product was characterized using Fourier Transform Infrared Spectroscopy (FT-IR), Raman spectroscopy and Scanning Electron Microscopy equipped with an Energy Dispersive X-ray Spectrometer (SEM-EDX). Moreover, SEM and FT-IR were used to reveal the surface structures of the composite coatings and their transition from superhydrophobicity to superhydrophilicity which occurred after severe thermal treatment. The composite coatings slightly reduced the breathability of marble and sandstone and had practically no optical effect on the colour of the two stones. Moreover, the coatings offered good protection against water penetration by capillarity.

Selected Aspects Regarding the Restoration/Conservation of Traditional Wood and Masonry Building Materials: A Short Overview of the Last Decade Findings

“…In the case of marble, was even achieved a superhydrophobicity character (contact angle > 150 • ). The same approach was used by Aslanidou et al [129]. Using commercially available silica nanoparticles dispersed in commercial alkoxy silanes and organic fluoropolymer emulsion obtained superhydrophobic and superoleophobic coatings, successfully applied for the protection of masonry (marble, sandstone) and other materials (concrete, paper, silk), proving a good versatility of the method.…”

Development of Multifunctional Coatings for Protecting Stones and Lime Mortars of the Architectural Heritage

“…Different strategies of achieving water repellency have been proposed and discussed (Tserepi, Vlachopoulou and Gogolides 2006;Manoudis et al 2009). Most of them are based on the application of organic compounds: resins, acrylate-based compounds, waxes … (Alessandrini et al 2000;Toniolo et al 2002;Fermo et al 2014;Andreotti et al 2018;Aslanidou, Karapanagiotis and Lampakis 2018;Winandy, Schlebusch and Fischer 2019). Different anti-graffiti treatments depending on the easiness of their removal after several cleaning processes have been tested by Macchia et al (2019).…”

Recent Advances in Protective Coatings for Cultural Heritage–An Overview

“…The interest on the application of nanocomposites for CH protective coating is shown in the present literature, which counted hundreds of papers per year in the last decade [110], as well as by the recent Horizon 2020 project, titled "Nano-Cathedral" [111], dedicated to innovative solutions based on nanocomposites for protecting European historical buildings. Because of the large amount of literature on these kinds of materials, we report here some of the results, which allow an in-depth discussion on these applications, whereas additional details can be found in cited references and reviews [112][113][114][115][116][117].…”

“…discussion on these applications, whereas additional details can be found in cited references and reviews [112][113][114][115][116][117].…”