Single-Solvent Fractionation of Enzymatic Hydrolyzed Lignin for Sustainable High-Performance Materials: Waterborne Polyurethane, Photothermal Coatings, and Eutectogels

Lignin is a very interesting material. However, the molecular weight distributions of all lignins extracted by various methods are quite large; lignin is a mixture of molecules with different degrees of polymerization. In this study, enzymatic hydrolyzed lignin (EHL) was graded by a single solvent method to obtain three lignins with a more uniform molecular distribution. These lignins were used for the preparation of different materials according to their molecular weight, hydroxyl content, and yield. Three fractions of EHL were used to synthesize waterborne polyurethane (WPU), photothermal conversion coating, and eutectogel, respectively. The performance of materials with added lignin has shown significant improvement. The bonding strength of WPU with lignin is greatly improved compared to WPU without lignin, the maximum temperature of photothermal conversion coating with lignin added increased twice, and the synthesis time and synthesis temperature of eutectogel with lignin added also decreased significantly. This research unlocks a wide application of EHL and provides more possibilities for the high-value utilization of lignin.