Acetylation of Never-Dried Wood via Diffusion-Driven Solvent Exchange

Acetylation is one of the most widely applied chemical modification methods for enhancing the dimensional stability and durability of wood. In this work, we investigate a diffusion-driven solvent-exchange method for acetylating never-dried Scots pine wood, eliminating the energy-intensive drying typically required before wood acetylation. Results from two-dimensional confocal Raman microspectroscopic imaging, coupled with multivariate data analysis and high-performance liquid chromatography, suggest a uniform distribution of acetyl groups within the cell walls and increased lignin acetylation using the solvent-exchange method. The uniform distribution of acetyl groups and increased lignin modification in the cell corners and the middle lamella resulted in less shrinkage and much-improved antiswelling efficiency at the macroscale. Overall, this diffusion-driven solvent-exchange pretreatment provides a uniform, direct acetylation of never-dried wood, bypassing the conventional oven- or kiln-drying step, with targeted lignin modification playing a crucial role in controlling wood-water interactions.