Enhancing the mechanical performance of lignin based hydrogel via lignin acetylation

Kraft lignin (KL) is an industrial byproduct of pulp preparation from woody biomass and is mainly burned for energy recovery. To explore value-added applications of KL, it was first acetylated, and acetylated lignin (AcL) was combined with poly(N,N-dimethylacrylamide) to prepare tough lignin hydrogels crosslinked by hydrophobic lignin domains via a simple solvent exchange method. The AcL hydrogels (AcLGs) with optimum mechanical properties have a high tensile strength of 1.7 MPa, large Young's modulus of 1 MPa, and super high fracture energy of ∼47600 J m−2. The Young's modulus and tensile strength of AcLG are 60 and 6 times higher than those of the pristine KL based hydrogel, respectively. AcLG had a weak inhibitory effect on Chinese hamster lung cell proliferation. Owing to its good mechanical properties and noncytotoxicity, AcLG has excellent potential as a biomedical material.