"Graft to" Modification of Lignin by the Combination of Enzyme-Initiated Reversible Addition-Fragmentation Chain Transfer and Grafting

Reversible addition-fragmentation chain-transfer (RAFT) polymerization demonstrates promise for preparing polymers with well-controlled weights and architectures. In this study, "one enzyme double catalysis" method applied in RAFT polymerization and grafting for lignin modification was reported. Acetylacetone (ACAC) radicals were generated by horseradish peroxidase (HRP) and hydrogen peroxide (H2O2), efficiently initiating well-controlled RAFT polymerization in the presence of chain-transfer agents. In this study, two vinyl monomers were polymerized, affording polymers with a controlled molecular weight and a low-molecular-weight distribution. In addition, this new "graft to" RAFT polymerization method catalyzed by the HRP/H2O2/ACAC system was carried out on lignin to prepare biocomposites. The difference between the grafted biocomposites and raw lignin was examined by Fourier transform infrared spectroscopy, and other analysis tests. The successful combination of HRP-initiated RAFT polymerization and enzyme-catalyzed graft modification will open a new avenue for the potential green polymerization of different monomers and green preparation of functional materials.