Weathering resistance of PMMA/SiO_2/ZrO_2 hybrid coatings for sandstone conservation

摘要

AbstractAccelerated weathering of polymethylmethacrylate (PMMA) and of hybrid PMMA/SiO2/ZrO2films was monitored by spectroscopic, thermal and colorimetric measurements. The hybrid polymers were obtained by sol-gel process adding tetraethylorthosilicate (TEOS) and zirconyl chloride (ZrOCl2*8H2O) to a solution of PMMA. Photo ageing tests on polymeric films under artificial sunlight irradiation in a climatic chamber suggest that the addition of the inorganic fillers slows down the chemical degradation of PMMA. The polymers were deposited on two different sandstones from Tuscany (Italy):Pietra DorataandPietra Serena. Capillary water absorption, contact angle and color measurements show that the hybrid-PMMA coatings retain the water repellency of the sandstone and do not introduce noticeable changes of the aesthetic appearance. Accelerated weathering of the treated sandstone confirms that the SiO2/ZrO2inorganic filler delays the chromatic changes of the polymer.The hybrid coating may then be proposed for application in the field of outdoor conservation of sandstones, used as building material in ancient and modern architectures.Highlights•Hybrid PMMA/SiO2/ZrO2polymers improve the photo-ageing resistance under UV–Vis irradiation.•The coatings on different sandstones preserve the protection after the ageing tests.•The hybrid polymers can be proposed as stone protective treatments.