ORIGINAL PAPER Dynamics property recovery of archaeological-wood fibers treated with polyethylene glycol demonstrated by high-resolution solid-state NMR Michel Bardet • Guillaume Gerbaud • Cha ˆu Doan • Mathilde Giffard • Sabine Hediger • Gae ¨l De Pae ¨pe • Quo ˆc-Kho ˆi Tra ˆn Received: 9 February 2012 / Accepted: 12 June 2012 / Published online: 24 June 2012 Ó Springer Science+Business Media B.V. 2012 Abstract We used high-resolution Solid-State 13 C NMR to better understand and optimize the conserva- tion process of archaeological waterlogged woods by polyethylene glycol (PEG) impregnation via the study of the molecular interactions between PEG and residual celluloses. By both deconvoluting NMR spectra and analyzing the behavior of 13 C magnetiza- tion build-up under proton to carbon cross-polariza- tion conditions, we were able to quantify PEG penetration and extract parameters sensitive to molec- ular dynamics such as proton spin lattice-relaxation- time constants in the rotating frame T 1qH and the cross-relaxation time constant T CH . By exploring a large range of PEG concentrations for the impregnat- ing solutions we show that the PEG penetrates inside the fibers and interacts at a molecular level with the cellulose fibrils thus restoring the dynamics properties of the damaged molecular cell wall network. At high PEG concentration, the polymer accumulates in the remaining free volume with more and looser molec- ular interactions with the residual wood components. This feature explains the facility for these hydroscopic materials to exude from the wood and led to delete- rious consequences for the restored artefacts. Keywords Solid-state NMR  Polyethylene glycol  Polymer cellulose interactions  Wood restoration  Archaeology  Waterlogged woods Introduction In archaeology, the excavation and treatment of waterlogged wooden objects is a challenge for the scientists in charge of their conservation. The most widespread methods are based on polyethylene glycol (PEG) impregnation since they are easy to handle even on very large objects such as shipwrecks (Pearson 1987). PEG toxicity and environment concerns are easy to control, even outside a laboratory context (Wallstrom and Lindberg 1995; Wallstrom et al. 1995). It is one of the favourite treatments of the conservators because of its reversible feature. Exten- sive studies have been performed to optimize the conservation process by taking into account features of different woods, which can drastically differ from one sample to another (Fors et al. 2011; Cavallaro M. Bardet (&)  G. Gerbaud  C. Doan  M. Giffard  S. Hediger  G. De Pae ¨pe Laboratoire de Chimie Inorganique et Biologique, UMR-E3(CEA/UJF) and CNRS, CEA/DSM/INAC, 38054 Grenoble, France e-mail: michel.bardet@cea.fr Present Address: G. Gerbaud CNRS, Bioe ´nerge ´tique et Inge ´nierie des proteins (UPR 9036), 31 Chemin Joseph Aiguier, 13402 Marseille, France Q.-K. Tra ˆn CEA, DRT, ARC-Nucle ´art, 38054 Grenoble Cedex 09, France 123 Cellulose (2012) 19:1537–1545 DOI 10.1007/s10570-012-9736-y