Structural features of lignin macromolecules extracted with ionic liquid from poplar wood

[Display omitted] ► We purified lignin macromolecule from cell wall of poplar wood using ionic liquid ([Emim][CH3COO]) and called to ionic liquid lignin (ILL). ► Structural features of ILL were compared with poplar milled wood lignin (MWL). ► Quantitative amounts of OMe and Phe-OH of ILL were similar to MWL. ► The weight average molecular weight (Mw) of ILL was determined to be 2/3-fold of that of MWL. 1-Ethyl-3-methylimidazolium acetate ([Emim][CH3COO]) was used for the extraction of lignin from poplar wood (Populus albaglandulosa), which was called to ionic liquid lignin (ILL) and structural features of ILL were compared with the corresponding milled wood lignin (MWL). Yields of ILL and MWL were 5.8±0.3% and 4.4±0.4%, respectively. The maximum decomposition rate (VM) and temperature (TM) corresponding to VM were 0.25%/°C and 308.2°C for ILL and 0.30%/°C and 381.3°C for MWL. The amounts of functional groups (OMe and phenolic OH) appeared to be similar for both lignins; approximately 15.5% and 6.7% for ILL and 14.4% and 6.3% for MWL. However, the weight average molecular weight (Mw) of ILL (6347Da) was determined to be 2/3-fold of that of MWL (10,002Da) and polydispersity index (PDI: Mw/Mn) suggested that the lignin fragments were more uniform in the ILL (PDI 1.62) than in the MWL (PDI 2.64).