Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Light Industry and Food Engineering, Nanjing Forestry University, Nanjing 210037, China.
Carbohydr Polym. 2021 Jan 1;251:117018. doi: 10.1016/j.carbpol.2020.117018. Epub 2020 Sep 1.
Deep eutectic solvents (DESs), as emerging green solvents, provide a new opportunity for the biorefinement of biomass, component extraction, and cellulose nanofibrillation. Herein, different carboxylic acid-based DESs were applied for preparation of cellulose nanofibers (CNFs) from cellulose raw materials accompanied by simultaneous esterification modifications of CNFs. The results showed that pretreatment of DESs combined with mechanical treatment can swell and esterify the cellulose materials, producing CNFs with widths less than 100 nm. The DES pretreatment temperature played important roles in the esterification modifications and nanofibrillation of cellulose. The esterification modifications of cellulose prevented the over-hydrolysis and dissolution of cellulose during the DES pretreatment, guaranteeing CNFs with high yields of 72 %-88 % and maintaining the cellulose I crystal structure. Moreover, the esterified CNFs were used as a reinforcement to prepare CNF-strengthened polylactic acid (PLA) composites. The surface esterification of the CNFs improved their dispersibility and interfacial compatibility with PLA, thereby achieving the mechanical enhancement of CNF/PLA composites.
深共熔溶剂（DESs）作为新兴的绿色溶剂，为生物质的生物炼制、成分提取和纤维素纳米纤维的制备提供了新的机会。本文中，不同的基于羧酸的 DESs 被应用于从纤维素原料中制备纤维素纳米纤维（CNFs），同时对 CNFs 进行酯化改性。结果表明，DESs 的预处理与机械处理相结合可以使纤维素材料溶胀和酯化，从而制备出宽度小于 100nm 的 CNFs。DES 预处理温度对纤维素的酯化改性和纳米纤维化起着重要作用。纤维素的酯化改性防止了 DES 预处理过程中纤维素的过度水解和溶解，保证了 CNFs 的高得率（72%-88%），并保持了纤维素 I 晶体结构。此外，酯化后的 CNFs 被用作增强剂来制备 CNF 增强聚乳酸（PLA）复合材料。CNFs 的表面酯化提高了它们在 PLA 中的分散性和界面相容性，从而实现了 CNF/PLA 复合材料的力学增强。
