Functional Lignin‐based Polymers: Isolation, Synthetic Methods and High‐valued Applications

Abstract As a major component of lignocellulosic biomass, lignin has lots of fascinating properties, such as regeneration, biocompatibility, antioxidant, hydrophilicity, unique aromatic structure, and various functional groups, which make them become interesting natural polymer raw material, and attracted more and more attention. In particular, the rich functional groups of lignin can be easily functionalized through various synthesis methods, which can endow lignin‐based polymers with new structure and function. These functional lignin‐based polymers are widely used in environmental remediation, smart hydrogel materials, catalysis, biomedical, etc. However, its various sources and types, the complex structure, relatively weak chemical reactivity, the unstable processing property, and few high value‐added products limited their practical applications. With the development of lignin varieties, modified reagent, synthesis methods, and polymerization process, many works had been published for the synthesis and application of lignin‐based polymers. In this review, the lignin isolation, modification strategies, polymerization method and process, and the promising applications were summarized and analyzed in recent years. Specially, the recent advances in the preparation of high excellent adsorbents from deconstructed lignin products are highlighted from the synthesis methods and adsorption mechanism perspective. Finally, we discussed these challenges in the green and controllable synthesis of lignin‐based polymers, and prospected their functional applications.