A Combined Theoretical and FT-IR Spectroscopy Study of a Hybrid Poly(furfuryl alcohol) - Lignin Material: Basic Chemistry of a Sustainable Wood Protection Method.

The sustainable wood protective modification known as furfurylation relies on the formation of a polymer of furfuryl alcohol (FA) that interacts with lignin within wood cell walls. In this study we gain new insight on the reaction by combining density functional theory based methods with an FTIR spectroscopic study. For a set of monolignol models we study their condensation reaction with FA and find the reaction enthalpy for their most reactive sites to be near-identical to FA self-condensation, and indistinguishable between p-hydroxyphenyl, guaiacyl and syringyl (H, G and S type) phenolic and non-phenolic models. For selected models experimental and predicted FTIR spectra confirmed FA condensation to uncrowded ring positions. However, for more realistic beta-O-4 dimer models we predicted the most reactive sites to be C alpha and C gamma in addition to the non-crowded ring positions. An analysis of expected prediction errors is presented too. We discuss the implications of these findings for the properties of the ligninpoly(FA) hybrid material within the wood cell wall.