Spruce milled wood lignin : Linear, branched or cross-linked?

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A2 Katsausartikkeli tieteellisessä aikakauslehdessä
Date
2020-07-07
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Language
en
Pages
17
3985-4001
Series
Green Chemistry, Volume 22, issue 13
Abstract
The subject of lignin structure, critical for fundamental and practical reasons, is addressed in this study that includes a review of the methods applied to elucidate macromolecular branching. The recently available approaches for determination of the absolute molecular mass of spruce milled wood lignin (MWL) along with the quantification of terminal groups clearly indicate that MWL is significantly branched and cross-linked (with ∼36% lignin units partaking in these linkages). Results from independent methods imply that about half of the branching and crosslinking linkages involve aromatic rings, predominantly 5-5′ etherified units; meanwhile, a significant number of linkages are located in the side chains. Quantitative 13C NMR analyses suggest that the branches involve different aliphatic ether (alkyl-O-alkyl) types at the α- and γ-positions of the side chain, with intact β-O-4 linkages. While the exact structures of these moieties require further investigation, our results point to the fact that conventional lignification theory disagrees with the presence of such key moieties in softwood MWL and the observed high degree of branching/crosslinking. Potential reasons for the noted discrepancies are discussed. This journal is
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Balakshin, M, Capanema, E A, Zhu, X, Sulaeva, I, Potthast, A, Rosenau, T & Rojas, O J 2020, ' Spruce milled wood lignin : Linear, branched or cross-linked? ', Green Chemistry, vol. 22, no. 13, pp. 3985-4001 . https://doi.org/10.1039/d0gc00926a