RT info:eu-repo/semantics/article T1 Understanding sulfonated kraft lignin re-polymerization by ultrafast reactions in supercritical water A1 Adamovic, Tijana A1 Zhu, Xuhai A1 Pérez, Eduardo A1 Balakshin, Mikhail A1 Cocero Alonso, María José K1 Diarylmethanes K1 Diarilmetano K1 Vanillin K1 Vanilina K1 Supercritical water K1 Agua supercrítica AB Re-polymerization reactions are a commonly reported issue on the way to the higher recovery of monomers from lignin. The reactivity of monomers obtained from lignin depolymerization and their contribution to the re-polymerization in supercritical water (SCW) was investigated. Sulfonated Kraft lignin (SKL) was used along with four monomers: vanillin, vanillic acid, vanillyl alcohol and acetovanillone. Indulin Kraft lignin was also employed as the reference to understand the re-polymerization of SKL in SCW. The formation of diarylmethane structures was detected in HSQC spectra of solid residue after the SCW process. Lignin released fragments with free phenolic β-O-4 structures, as well as the monomeric product vanillyl alcohol are involved with the formation of o-o´ and o-p´ diarylmethane structures. Chemical structure of Kraft lignin and its polymeric product after the SCW process was remarkably similar, as shown by HSQC, indicating that re-polymerization reactions occur through cross-linking polymerization, mainly in their fractions of low molecular weight products. PB Elsevier SN 0896-8446 YR 2022 FD 2022 LK https://uvadoc.uva.es/handle/10324/55973 UL https://uvadoc.uva.es/handle/10324/55973 LA eng NO The Journal of Supercritical Fluids, Volume 191, 2022, 105768 NO Producción Científica DS UVaDOC RD 07-ago-2024