Fabrication and Characterization of Cellulose-based Hydrogels with Polymerizable Ionic Liquids for 3D Printing Applications

Abstract Cellulose is an abundant, sustainable, and low-cost material; however, its strong intra- and intermolecular hydrogen bonding makes it insoluble in water and most organic solvents. Ionic liquids such as 1-butyl-3-methylimidazolium chloride ([C₄mim]Cl) have therefore been widely used to dissolve and process cellulose under mild conditions. In this study, cellulose-based hydrogels were prepared using cellulose, [C₄mim]Cl, and an ionic liquid (IL) monomer. The crystallinity and chemical structure of the hydrogels were characterized, and their water content and mechanical properties were evaluated as a function of cellulose concentration. Incorporation of polymerized ionic liquid (PIL) into the cellulose network significantly enhanced the mechanical strength compared to conventional cellulose hydrogels. Antibacterial activity was assessed by the disk diffusion method. In addition, the rheological behavior of cellulose solutions was investigated, and the resulting inks were successfully applied to 3D printing. The cellulose/PIL hydrogels exhibited high water content, improved mechanical strength, and excellent printability. Although [C₄mim]Cl effectively inhibited Escherichia coli growth, this antibacterial effect was lost after washing the hydrogels. These results demonstrate that cellulose/PIL hydrogels are promising structural platforms for functional materials, with tunable properties suitable for future specialized and potentially biomedical applications.