Facile Preparation and Characteristic Analysis of Sulfated Cellulose Nanofibril via the Pretreatment of Sulfamic Acid-Glycerol Based Deep Eutectic Solvents

A deep eutectic solvent (DES) composed of sulfamic acid and glycerol allowed for the sustainable preparation of cellulose nanofibrils (CNF) with simultaneous sulfation. The reaction time and the levels of sulfamic acid demonstrated that fibers could be swelled and sulfated simultaneously by a sulfamic acid-glycerol-based DES and swelling also promoted sulfation with a high degree of substitution (0.12). The DES-pretreated fibers were further nanofibrillated by a grinder producing CNF with diameters from 10 nm to 25 nm. The crystallinity ranged from 53-62%, and CNF maintained the original crystal structure. DES pretreatment facilitated cellulose nano-fibrillation and reduced the energy consumption with a maximum reduction of 35%. The films prepared from polyvinyl alcohol (PVA) and CNF showed good UV resistance ability and mechanical properties. This facile and efficient method provided a more sustainable strategy for the swelling, functionalization and nano-fibrillation of cellulose, expanding its application to UV-blocking materials and related fields.

Automated summary

The use of a deep eutectic solvent enabled the sustainable preparation of cellulose nanofibrils with simultaneous swelling and sulfation, leading to the production of CNF with diameters ranging from 10 nm to 25 nm after further nanofibrillation. DES pretreatment facilitated cellulose nano-fibrillation, reduced energy consumption, and resulted in PVA and CNF films with good UV resistance and mechanical properties. This efficient method offers a more sustainable strategy for cellulose swelling, functionalization, and nano-fibrillation, expanding its application to UV-blocking materials and related fields.