Controllable preparation of nano-cellulose via natural deep eutectic solvents prepared with lactate and choline chloride

Pretreatment with deep eutectic solvent is highly desirable to improve the efficiency of the preparation of nanocellulose and simplify the operation. The natural deep eutectic solvent (NADES) composed of lactate (LA) and choline chloride (CC) was applied for the preparation of nano-cellulose under mild conditions accompanied by simultaneous esterification modifications of it. The effects of the treatment conditions on the structure and properties of nano-cellulose were investigated and explained the mechanism from the perspective of molecular simulation. The results showed that the reaction time of nano-cellulose could be shortened to 3 h, and the reaction temperature could be as low as 100 degrees C. The esterification of cellulose not only avoided over-hydrolysis and dissolution in the pretreatment process but also ensured the high yield of nano-cellulose (up to 75 % 89 %). The crystallinity of nano-cellulose decreased compared with the raw material due to the influence of mechanical action. The nano-cellulose fibers (NCF) and nano-cellulose crystals (NCC) with different lengths were achieved by controlling the reaction conditions of the pretreatment of NADES. The esterification modifications of NADES on cellulose during the dissolution of nano-cellulose were confirmed by molecular simulation. The nano-cellulose prepared by this system has good stability, biocompatibility, and degradability, which can be used in the fields of medicine, strengthening composite materials, and emulsion emulsifiers.

Automated summary

Pretreatment with deep eutectic solvent is highly desirable for efficient preparation of nanocellulose. Natural deep eutectic solvent (NADES) composed of lactate and choline chloride was used to prepare nano-cellulose under mild conditions, accompanied by simultaneous esterification modifications. The treatment conditions affected the structure and properties of the nano-cellulose, and molecular simulation explained the mechanism. The prepared nano-cellulose showed good stability, biocompatibility, and degradability, making it suitable for various applications.