The effect of organosilicon compounds on the nanostructure of waterlogged archeological oak studied by neutron and X-ray scattering

Selected organosilicon compounds proved effective in stabilizing waterlogged wood dimensions upon drying. However, detailed knowledge about their effect on wood is necessary before introducing them as safe waterlogged wood consolidants in conservation practice. Our previous research showed that organosilicons can chemically react with wood polymers, infiltrate cell walls and/or fill cell lumina. These interactions can mechanically reinforce the cell wall or have a plasticizing effect on wood, depending on the compound applied. To better understand their stabilizing effect on waterlogged wood, we used neutron and X-ray scattering methods, which enabled us to study the nanostructure of archeological oak wood and recognize if and how treatment with selected organosilicon compounds modified it. The results showed that archeological wood had a reduced amount of crystalline cellulose and a less ordered nanostructure with larger elementary fibrils that are more loosely packed compared to sound wood. X-ray and neutron scattering also revealed that applied alkoxysilanes restored the long-range cellulose arrangement in archaeological oak samples to different extents, whereas siloxane did not. This restoration was visible in increased anisotropy in the SAXS/SANS patterns and increased intensity in the WAXS data. The most effective silane treatment restored both SAXS/SANS and WAXS features. Combining the macroscale characterization of treated and untreated archaeological oak with the X-ray and neutron scattering work suggests that the nanoscale changes in the cell wall imparted by the infiltration of selected organosilicons contribute to the increased dimensional stability of archeological wood treated with these compounds.