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 °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.