Abstract
The lignin-based polymers (lignophenols) were synthesized through the phase-separation system composed of the concentrated acid and p-alkylphenols. The relationship between the structures of phenols constituting the organic phase and functionalization effects of lignin in the phase-separation reaction was discussed. The lignin functionalization rate got lower with the extension of alkyl substituents on phenolic nuclei, due to the hydrophobicity and steric hindrance of alkyl substituents. The depolymerizations of lignophenols were the participation of C1-phenolic nuclei in alkaline media. Both spruce and maple lignophenols were effectively depolymerized by the treatment with 0.5N NaOH at 120°C to 170°C. There was a good correlation between the frequency of grafted phenolic nuclei and the depolymerization degree of lignophenols, independent of the structures of grafted phenols.
