Synthesis of Alkaline-Soluble Cellulose Methyl Carbamate Using a Reactive Deep Eutectic Solvent

This study presents the use of a reactive deep eutectic solvent (DES) for the chemical modification of wood cellulose fibers. DES based on dimethylurea and ZnCl2 was used to synthetize cellulose methyl carbamate (CMeC). This synthesis was performed at elevated temperature under solvent-free conditions. Chemical characterization based on FTIR and NMR indicated that methyl carbamate was successfully introduced to cellulose, and a degree of substitution (DS) of 0.17 was obtained after 3 h of reaction at 150 degrees C. The product with a DS of 0.17 exhibited good alkaline solubility (in 3% NaOH solution) after freeze-thawing, whereas the original cellulose fibers were practically insoluble even in 9% NaOH. As dimethylurea can be produced from CO2, this method can be used as a sustainable way to obtain novel cellulose materials with desirable properties for use in a wide range of applications.