Chemo-enzymatic synthesis and characterization of graft copolymers from lignin and acrylic compounds

Chemo-enzymatic initiation of graft copolymerization of acrylic compounds onto different technical lignosulfonates (LS) was compared to a Fenton-like system (ferrous ion, t-BHP). The enzyme tested was a phenoloxidase laccase (EC 1.10.3.2) from the white rot basidomycete Trametes versicolor. Most applied lignins were successfully grafted, resulting in a polymer yield of more than 90%. The effect of initiator concentration and the lignin/monomer ratio on the yield and M̄w of enzymatically grafted polymers were studied. The homopolymer proportion in the enzymatically produced grafts of Ca-LS and acrylic acid was 5 to 6× lower than those initiated by the Fenton-like reagent; no such differences were observed for Na-LS.