Impact of ionic liquid's cation alkyl chain length and reaction time on cellulose nanocrystals preparation

• Published in: Carbohydrate Polymer Technologies and Applications
• Main Authors: Jania Betania Alves da Silva, Suellen Rocha Vieira, Luiggi Cavalcanti Pessôa, Jamille Santos Santana, Paulo Vitor França Lemos, Carolina Oliveira de Souza, Lucas Guimarães Cardoso, Denílson de Jesus Assis, Cassamo Ussemane Mussagy, Valéria Carvalho Santos‑Ebinuma
• Format: Article
• Language: English
• Published: Elsevier 2023-12-01
• Subjects: Protic ionic liquids; Cellulose nanoparticles; Microcrystalline cellulose; Hydrolysis
• Online Access: http://www.sciencedirect.com/science/article/pii/S2666893923001111

Traditional methods to obtain cellulose nanocrystals typically involve mechanical and chemical processes and develop an improved process in terms of efficiency, sustainability, and the quality of CNCs produced are interesting. In this sense, we aimed to prepare cellulose nanocrystals (CNCs) from the hydrolysis of microcrystalline cellulose using protic ionic liquids (PILs), named 3-diethylamino-propylammonium hexanoate ([DEAPA][Hex]), 3-dimethylamino- 1-propylammonium hexanoate ([DMAPA][Hex]), and propylammonium hexanoate ([PA][Hex]) at different reaction times. The PILs demonstrated efficiency in producing cellulose nanocrystals, regardless of the cation size and reaction times. However, as expected the properties of the CNCs varied depending on the studied condition. The highest yield was observed in DMAPA[Hex], with a 34 % conversion. Crystalline indices decreased independent of the cation sizes and reaction times. Thermal stabilities were shifted to higher temperatures up to 92 ºC probably due to PILs cation sizes. In contrast, increasing reaction times decreased nanocrystals’ thermal stabilities up to 51ºC. So, protic ionic liquids (PILs) can be considered more environmentally friendly or sustainable solvents compared to traditional organic solvents for preparing cellulose nanocrystals. In the present work, it is reported an alternative method for obtaining CNCs and additionally provide the best preparation conditions for achieving important properties of this nanomaterial, with the potential for various applications.