Halloysite nanotubes for Cultural Heritage : from fundamental science to applications

Orateur : Giuseppe LAZZARA (Dipartimento di Fisica e Chimica, Università degli Studi di Palermo, Viale delle Scienze, pad. 17, 90128 Palermo, Italy - Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali, INSTM, Via G. Giusti, 9, I-50121 Firenze, Italy)

In the last years, innovative strategies based on clay nanoparticles have been proposed for conservation of cultural heritages, including the consolidation/protection of lignocellulosic materials as well as the protective coating/cleaning of solid surfaces. Among the nanoclays, halloysite nanotubes are promising because of their hollow tubular shape, tunable interface chemistry and high specific surface. Here, we investigated the efficiency of hybrid materials based on halloysite as protective consolidants of waterlogged archeological woods as well as cleaners for solid substrates. We observed that the consolidation of archeological wood by polyethylene glycol/Halloysite aqueous mixtures confers robustness and mechanical resistance (in terms of flexural strength and rigidity) to the wooden structure. These effects are related to the homogenous penetration of the nanotubes within the channels of the archeological wood. In addition, the encapsulation of calcium hydroxide within the Halloysite lumen provides an alkaline nanoreservoir that is effective for the long-term protection of lignin. This finding was proved by both the pH and the lignin index (determined by FT-IR spectroscopy) of wood exposed to artificial aging under acidic atmosphere.1 On the other hand, we detected that the combination of organic macromolecules, hydrocarbons and Halloysite represents an alternative strategy for the cleaning of solid surfaces. In this regards, oil in water microemulsions based on halloysite were employed for the cleaning of marble substrates. Halloysite can be considered a valuable nanomaterial in this application because it allows to a controlled cleaning reducing the risks of residues on the artfacts surface. In conclusion, it’ll be evidenced that halloysite is a suitable clay nanoparticle in designing ecocompatible protocols for the durable preservation of lignocellulosic artworks as well as for the cleaning of artworks.

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