Silica-Functionalized Nanolimes for the Conservation of Stone Heritage
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2023-04-18Abstract
The relatively recent development of nanolimes (i.e., alcoholic dispersions of
Ca(OH)2 nanoparticles) has paved the way for new approaches to the conservation of important art works. Despite their many benefits, nanolimes have
shown limited reactivity, back-migration, poor penetration, and lack of proper
bonding to silicate substrates. In this work a novel solvothermal synthesis
process is presented by which extremely reactive nanostructured Ca(OH)2
particles are obtained using calcium ethoxide as the main precursor species.
Moreover, it is demonstrated that this material can be easily functionalized
with silica-gel derivatives under mild synthesis conditions, thereby preventing
particle growth, increasing total specific surface area, enhancing reactivity,
modifying colloidal behavior, and functioning as self-integrated coupling
agents. Additionally, the formation of calcium silicate hydrate (CSH) nanocement is promoted by the presence of water, resulting in optimal bonding
when applied to silicate substrates, as evidenced by the higher reinforcement effect produced on treated Prague sandstone specimens as compared
to those consolidated with nonfunctionalized commercial nanolime. The
functionalization of nanolimes is not only a promising strategy for the design
of optimized consolidation treatments for the cultural heritage, but may also
have important implications for the development of advanced nanomaterials
for building, environmental, or biomedical applications.