Pickering Emulsions Based on Wax and Halloysite Nanotubes: An Ecofriendly Protocol for the Treatment of Archeological Woods

Abstract

A novel green protocol for the consolidation and protection of waterlogged archeological woods with wax microparticles has been designed. First, we focused on the development of halloysite nanotubes (HNTs) based Pickering emulsions using wax as the inner phase of the oil-in-water droplets. The optimization of the preparation strategy was supported by both optical microscopy and scanning electron microscopy, which allowed us to show the morphological features of the prepared hybrid systems and their structural properties, i.e., the distribution of the clay at the interface. Also, the dependence of the overall dimensions of the prepared systems on the halloysite content was demonstrated. Microdifferential scanning calorimetry (μ-DSC) was conducted in order to assess whether the thermal properties of the wax are affected after its interaction with HNTs. Then, the Pickering emulsions were employed for the treatment of waterlogged wooden samples. Compared to the archeological woods treated with pure wax, the addition of nanotubes induced a remarkable improvement in the mechanical performance in terms of stiffness and flexural strength. The proposed protocol is environmentally friendly since water is the only solvent used throughout the entire procedure, even if wax is vehiculated into the pores at room temperature. As a consequence, the design of wax/halloysite Pickering emulsions represents a promising strategy for the preservation of wooden artworks, and it has a great potential to be scaled up, thus becoming also exploitable for the treatments of shipwrecks of large size.

Halloysite Nanotubes with Immobilized Plasmonic Nanoparticles for Biophotonic Applications

“…The pronounced plasmonic responses of those nanocomposites allow us to consider them also as potential labels in optical reflection microscopy. Besides their biphotonic applications, HNT-based nanocomposites are of continuing interest in various applications [32][33][34][35]. The discussed diagnostics and therapeutic abilities of HNTs with attached plasmonic nanoparticles make them attractive for the development of new biophonic and biomedical methods.…”

Sepiolite-Hydrogels: Synthesis by Ultrasound Irradiation and Their Use for the Preparation of Functional Clay-Based Nanoarchitectured Materials

“…Both clay minerals are usually present in nature as micron or submicron sized particles (Bauluz-Lazaro, 2015). External and luminal diameters of halloysite range from 20 to 150 nm and from 10 to 15 nm, respectively (Lisuzzo et al, 2021). Kaolinite and halloysite exhibit a limited capacity to intercalate small neutral polar molecules (e.g., urea, N-methylformamide, DMSO), which can be retained between the silicate layers, although halloysite can additionally insert diverse components inside the core lumen.…”

Drying Stress and Strain of Wood: A Review

“…Sci. 2021, 11, 5023 2 of 19 the possibility of organosilicons as consolidants to improve the dimensional stability of drying; adding nanotubes to the process to solve mechanical performance problems; and so on [15][16][17].…”