Comparative hydrodynamic characterisation of two hydroxylated polymers based on α-pinene- or oleic acid-derived monomers for potential use as archaeological consolidants

Abstract

The Oseberg Viking ship burial is one of the most extensive collections of Viking wooden artefacts ever excavated in Norway. In the early twentieth century, many of these artefacts were treated with alum in order to preserve them, inadvertently leading to their current degraded state. It is therefore crucial to develop new bioinspired polymers which could be used to conserve these artefacts and prevent further disintegration. Two hydroxylated polymers were synthesised (TPA6 and TPA7), using α-pinene- and oleic acid-derived monomers functionalised with an acrylate moiety. Characterisation using biomolecular hydrodynamics (analytical ultracentrifugation and high precision viscometry) has shown that these polymers have properties which would potentially make them good wood consolidants. Conformation analyses with the viscosity increment (ν) universal hydrodynamic parameter and ELLIPS1 software showed that both polymers had extended conformations, facilitating in situ networking when applied to wood. SEDFIT-MSTAR analyses of sedimentation equilibrium data indicates a weight average molar mass Mw of (3.9 ± 0.8) kDa and (4.2 ± 0.2) kDa for TPA6 and TPA7 respectively. Analyses with SEDFIT (sedimentation velocity) and MultiSig however revealed that TPA7 had a much greater homogeneity and a lower proportion of aggregation. These studies suggest that both these polymers—particularly TPA7—have characteristics suitable for wood consolidation, such as an optimal molar mass, conformation and a hydroxylated nature, making them interesting leads for further research.

Evaluation of two terpene-derived polymers as consolidants for archaeological wood

“…Figure 1 The structures for the two terpene-derived polymers that were evaluated in this study. Their synthesis and characterisation have already been described in a previous paper 10 .…”

“…Examples of materials that have been investigated include lignin 3 , isoeugenol 4,5 , chitosan 6,7 and aminocellulose 8 . Most recently, we have developed polymers derived from terpenes with functionalised hydroxylated moieties 9,10 . In this work we wanted to further investigate the potential of two of these polymers, TPA6 and TPA7 (Fig.…”

Evaluation of two terpene-derived polymers as consolidants for archaeological wood

“…Examples of materials that have been investigated include lignin 4 , isoeugenol 8 , 9 , chitosan 5 , 10 and aminocellulose 11 . Most recently, we have developed polymers derived from terpenes with functionalised hydroxylated moieties 12 , 13 . In this work we wanted to further investigate the potential of two of these polymers, TPA6 and TPA7 (Fig.…”

“…TPA7 is a copolymer derived from this same terpene monomer along with an oleic acid-based comonomer and has a M w of 4.2 kDa. The T g values for TPA6 and TPA7 were measured to be 31.1 °C and 18.9 °C respectively 13 . Both are yellow solids at room temperature and 50 g of each polymer was available for the wood testing.…”

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Figure 1 The structures for the two terpene-derived polymers that were evaluated in this study. Their synthesis and characterisation have already been described in a previous paper 13 .

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