The fluorescence characteristics of furfurylated wood studied by fluorescence spectroscopy and confocal laser scanning microscopy

The fluorescence of furfurylated wood was studied. Furfurylation of wood introduced fluorescent curing products into the cell walls. Fluorescent products were also found in the lumina if high loadings were used and/or if the wood contained cells with small radii. More intense fluorescence was obtained from lignin-rich parts of the compound cell wall (i.e., the middle lamella and the cell corners) than from the secondary cell wall if the wood was impregnated using furfuryl alcohol (FA), while impregnation using small poly(FA) oligomers showed no or only minor differences between different regions. The study also showed that when higher amounts of catalyst were added to the impregnation liquid, a red-shift in the fluorescence from the furfurylated wood was seen, corresponding to an increased conjugation length of conjugated poly(FA) formed within the wood cell wall. Longer conjugation length than within the cell wall was observed for the poly(FA) formed within the lumina. This indicates that the cell wall polymers restrict poly(FA) formation.