Peroxidase-catalyzed polymerization and copolymerization of lignin-based macromonomer (lignocresol) having high content ofp-cresol and thermal properties of the resulting polymers

Peroxidase-catalyzed polymerization of lignin-based macromonomer, lignocresol, which was prepared by the phase-separation system of lignin and p-cresol in aqueous sulfuric acid, was carried out for the first time in aqueous organic solvents to give insoluble polymers in 55% yield. It was found that the polymerizability of lignocresol by peroxidase was enhanced by the introduction of p-cresol in lignin side-chains compared to that of original lignin. Copolymerization of lignocresol with p-cresol gave the corresponding copolymers in high yields. From the IR results, lignocresol might be polymerized through a phenoxyl radical. The pyrolysis gas chromatography-mass spectrometry (GC-MS) analysis of the polymers obtained indicated that the polymerization of lignocresol involved mainly the oxidative coupling at the introduced p-cresol. The thermal properties of the polymers obtained were characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) measurements, suggesting that the polymers have high thermal stability according to the crosslinked structures. Copyright © 2005 John Wiley & Sons, Ltd.