Quaternary ammonium silane modified Nanolime for the consolidation and antifungal of stone relics

Abstract

Cultural relics such as wall paintings and stone relics face a decrease in mechanical strength and contamination from microbial growth. Nanolime (NL), as an exceptional inorganic nanomaterial used in the consolidation of cultural heritages, has been investigated for more than two decades. However, it has limited antibacterial properties. Here, we opted for dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (DC5700) to modify the surface of NL particles, praparing an organic–inorganic hybrid nanomaterial (NL-DC5700) that provides long-lasting antifungal effects for stone samples without sacrificing its consolidation effect. Characterizations demonstrate that DC5700 grafts onto the surface of NL particles through the formation of covalent bonds via dehydration condensation between the siloxane of DC5700 and the hydroxyl of NL, forming an organic shell layer that uniformly wraps the NL particles. NL-DC5700 can endow stone samples with near superhydrophobicity (NL, 25.4° and NL-DC5700, 142.0°) and durable antifungal effects over 90 days, superior to those of pure NL. NL-DC5700 shows no unacceptable impact on the appearance, porosity, or microstructure of the stone specimens. Our work explores the antifungal effect of NL-based materials and provides fresh insights into the development of versatile conservation materials for stone relics.