Titanium dioxide-based nanocoating to conservation of rigid PUR foams on cultural heritage

Abstract

Several studies have investigated the conservation of polymers, as rigid polyurethane (PUR) foams, in cultural heritage. These materials are highly susceptible to various environmental conditions within museum environment, including hydrolytic, thermal, and photo-oxidative processes, affecting its structural stability and promotes discoloration and/or yellowing. In response to these challenges, this research proposes the development of nanocoatings based on titanium dioxide surface functionalization with different organosilanes to protect artworks from degradation processes caused by the museum environmental conditions. For this, two surface modifiers were employed: (3-aminopropyl)triethoxysilane, that enhances chemical affinity with the foam; and (n-octyl)triethoxysilane, that contributes to increase the hydrophobicity of the samples. The functionalization reactions involved varying ratio of organosilanes, and the spectroscopic and thermal analyzes confirmed the successful modifications. Subsequently, the modified titanium dioxides particles were added to a surface of rigid PUR foam based on polyether and polyester using an ethanol dispersion. The nanocoated samples then were submitted to an artificial aging process in a climatic chamber under controlled temperature, humidity, and exposure to ultraviolet radiation. Comparative evaluations were conducted before and after treatment, employing visual, morphological, spectroscopic, and dynamical mechanical analyzes. The results demonstrated that the different formulations exhibited good surface adhesion to the foam and effectively limited visual degradation while preserving the foam’s properties. These findings serve as a promising starting point for the development of innovative approaches to preserve PUR artistic works.