Lignin is a unique and abundant natural biopolymer that accounts for 15-30% of the dry weight of biomass. Previous studies have shown that lignin is a non-crystalline and highly branched phenolic polymer. Lignin imparts structural strength and biological activity to plants and plays an important role in pathogen defense, water and nutrient transport. Its physicochemical properties play a crucial role in the production of the material. Therefore, elucidating the structural characteristics of lignin is a prerequisite for its efficient use.
To date, researchers have mainly degraded lignin by destructive methods in order to analyze the structure of lignin. In this approach, its structural features are likely to be altered as a result of the degradation process. In addition, lignin-carbohydrate complexes (LCCs) make it more difficult to isolate lignin from lignocellulosic biomass (LCBM) and analyze its structure. It is therefore essential to develop new techniques for mapping accurate structures of whole lignin. The development of techniques and instrumentation in the biophysical field offers the possibility of studying the structure of lignin as a whole.
Fig.1 UV-Vis spectra of four lignins. (Lu, 2017)