Extended Data Fig. 6: Characterization of FPLs before and after hot-pressing.

a, GPC spectra and molecular weights of hydrogenolysis products from FPLs before and after hot-pressing. b, c, C1s in XPS spectra (b) and the contents of carbon-based linkages (c). d, Hydorgenolysis monomer yields of FPL and hot-pressed FPLs. The hot-pressed lignins were prepared by hot-pressing FPLs wrapped by aluminum foil. Hot-pressing conditions: lignin/water = 1: 2 (w: w), 190 °C (hot-pressing temperature), 8 min (hot-pressing time), pH = 7, and 1.5 MPa (hot-pressing pressure). Increased C–C and decreased C–O contents were observed after hot-pressing FPLs at 190 °C, indicating that a high temperature facilitated the occurrence of condensation or the formation of additional C–C linkages in FPLs during hot-pressing. The structures of silylated lignin monomers (M1–M9) were given in Extended Data Fig. 2.