One-pot strategy to enhance nanofibrillation and esterification of cellulose using ternary deep eutectic solvent

Abstract

Establishing green and efficient method for the nanofibrillation and modification of cellulose is the foundation to prepare the cellulose functional material. Herein, we provided a "one-pot " strategy to achieve the high-efficiency nanofibrillation and esterification of nanocellulose using the ternary deep eutectic solvents (DESs). The widths of cellulose nanofiber (CNF) with 18.9 ± 2 nm were successfully prepared by swelling with maleic acid/choline chloride (MA/ChCl) DES at 100 °C for 3 h, followed by mechanical colloid milling. The corresponding acid anhydrides maleic anhydrides (MAH) was added to form MAH/MA/ChCl DES for enhanced esterification of nanocellulose. As a result, the nanocellulose achieved a high degree of substitution (DS) of up to 0.84. The feasibility of "one-pot " strategy based on other ternary DESs (acetic anhydride/acetic acid/choline chloride (AAH/AA/ChCl), succinic anhydride/succinic acid/choline chloride (SAH/SA/ChCl) as representative) was further studied to fibrillate and esterify nanofibers, demonstrating it is an efficient method for the nanofibrillation and modification of cellulose.