Novel ultraviolet-curable methacrylate nanocomposite as coatings for cultural heritage applications

Abstract

The aim of the research was to develop, optimize and characterize photopolymerizable siloxane-modified methacrylicbased nanosystems, expressly designed for the preservation and protection of materials for cultural heritage (wood, natural stone, etc.). A methacrylate-based ultraviolet-curable resin was chosen since it is characterized by a high reactivity, even at room temperature, when compared to commercial thermosetting products thermally polymerized in situ. Moreover, the ultraviolet cure process allows to solve environmental problems related to the use of polymers in solution since it drastically reduces volatile solvent emission. The nanostructured ultraviolet-cured products, obtained with the inclusion of organically modified boehmite, are expected to lead to protective films with high final performance in terms of surface properties and hydrophobicity. The experimental formulations were deeply investigated, in both the liquid and the solid states. The dimensions of the nanoparticles in the ultraviolet-curable liquid formulations were first estimated by dynamic light scattering analysis. Photocalorimetric analysis was employed to analyze the ultravioletinduced radical photopolymerization reaction mechanisms. The viscosity of the formulations produced was analyzed, using a plate and plate rheometer, as a function of the shear rate. The formulations were photocured on a glass substrate, using a medium-pressure Hg ultraviolet lamp, and the following properties were measured: transparency, scratch and surface hardness, glass transition temperature and contact angle with water. © IMechE 2013.