Multifunctional supramolecular polymer networks as next-generation consolidants for archaeological wood conservation

• Published in: Proceedings of the National Academy of Sciences - PNAS 2014-12, Vol.111 (50), p.17743-17748
• Main Authors: Walsh, Zarah, Janeček, Emma-Rose, Hodgkinson, James T., Sedlmair, Julia, Koutsioubas, Alexandros, Spring, David R., Welch, Martin, Hirschmugl, Carol J., Toprakcioglu, Chris, Nitschke, Jonathan R., Jones, Mark, Scherman, Oren A.
• Format: Article
• Language: English
• Subjects: Archaeological conservation; Biodegradation; Catalysis; Chemical degradation; Chemicals; Conservation; Environmental conservation; Gels; Imaging; Material culture; Materials; Molecules; Oxalic acid; Physical Sciences; Polymer chemistry; Polymers; Preservation; Timber; Wood
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1406037111

The preservation of our cultural heritage is of great importance to future generations. Despite this, significant problems have arisen with the conservation of waterlogged wooden artifacts. Three major issues facing conservators are structural instability on drying, biological degradation, and chemical degradation on account of Fe ³⁺-catalyzed production of sulfuric and oxalic acid in the waterlogged timbers. Currently, no conservation treatment exists that effectively addresses all three issues simultaneously. A new conservation treatment is reported here based on a supramolecular polymer network constructed from natural polymers with dynamic cross-linking formed by a combination of both host-guest complexation and a strong siderophore pendant from a polymer backbone. Consequently, the proposed consolidant has the ability to chelate and trap iron while enhancing structural stability. The incorporation of antibacterial moieties through a dynamic covalent linkage into the network provides the material with improved biological resistance. Exploiting an environmentally compatible natural material with completely reversible chemistries is a safer, greener alternative to current strategies and may extend the lifetime of many culturally relevant waterlogged artifacts around the world. Significance The preservation of cultural heritage is of widespread importance all over the world. Yet the lack of development in the field of conservation treatments means the fate of some of the most culturally important artifacts in the world remain in jeopardy. In the preservation of waterlogged wooden artifacts, conservators rely almost exclusively on poly(ethylene glycol) doped with a broad-spectrum biocide. The concept of a chemotactic consolidant, one that can adapt to the artifact it is treating, as described here has never before been described for an archaeological/conservation treatment. Additionally, the cross-links holding the consolidant together are entirely reversible, resulting in a material that is a greener, safer, and sustainable alternative to current conservation strategies.