NANOMATERIALI PER IL TRATTAMENTO DELLE SUPERFICI DI MANUFATTI IN PIETRA E "MARMO" PER L'ARREDAMENTO DI INTERNI E OUTDOOR

S2 S.p.a, based in Fermignano (Pesaro-Urbino), is a company that since 1973 has been working in the wood sector and produces and markets finished products of interior furniture characterized by the most prestigious international brands of Made in Italy. In the last twenty years, the company also addressed its interest to various types of tables and other elements made of marble which therefore became a fundamental material for complementing and exclusive design for the needs of the international luxury living market. The need to treat the surfaces of stone and marble lithotypes to ensure maximum durability, for aesthetic qualities and waterproofing, together with the choice of S2 S.p.a also to target production for outdoor, lead the company to test innovative products. In this way, the Eureka doctoral program started in collaboration with S2 S.p.a with the final aim of being able to identify one or more nanometric size products to be applied to the surfaces of the tables, suitable for the whole spectrum of used carbonatic rocks and marbles currently in process and potential other lithotypes. This in order to ensure durability and maintenance of aesthetic qualities (as chromatic variations) and self-cleaning capacity, both for interior and outdoor furnitures. In addition, the testing of protective nano-coatings were aimed at compatibility with treatments already in use by S2 S.p.a. and the maintenance of physical mechanical strength and waterproofing features. There is currently a wealth of scientific literature on the use of nanometric materials for surface treatment of many types of marbles and carbonate rocks, either by semiconductors or biodegradable polymers, in liquid solutions, possibly with the addition of doping elements or mineral phases. Among the materials already tested to ensure the durability of surfaces of marbles and other rock lithotypes, titanium dioxide (TiO2) has been used with great success and interest, thanks to its super-hydrophilic characteristics and photocatalytic efficiency which guarantee self-cleaning, antibacterial and antifungal functions, and a reduction of pollution from NOx, SOx and volatile organic compounds. In this PhD thesis, nine lithologies of sedimentary rocks and marbles have been selected to be analyzed in agreement with the company S.p.a., namely Arabescato, Bianco Carrara, Calacatta, Dark Emperador, Nero Marquinia, Portoro Silver, Rosso Levanto, Sahara Noir and Verde Alpi. Physical properties of these rocks were firstly determined (i.e, porosity and porous distribution, bulk density, apparent density) and then, each lithology was examined in double samples, respectively with polished and satin finish and appropriately treated with solutions based on nanoparticles of titanium dioxide in different aqueous/alcoholic solutions or in alcohol doped with silver chloride. The samples, untreated and treated surfaces with the three different protective TiO2-based nano-coating solutions were subjected to tests of: (i) water absorption by capillarity; (ii) roughness through profilometry to characterize the surface morphology of each lithology (pre-and post titanium bioxide treatment) and finally (iii) colorimetry with rodamine B dye method to determine photocatalytic self-cleaning activities in the surfaces of the marbles through the exposure to ultraviolet rays up to 26 hours. It was possible to evaluate the effects and changes in the natural aesthetic characteristics of the nine lithologies after the application of the different TiO2 nanoparticle coating-solutions and the relative self-cleaning photocatalytic activities.