Dissolution and Regeneration of Cellulose Using Superbase-Based Dicarboxylic Ionic Liquids with Tailored Amphiphilicity

Abstract

The processes of dissolving and regenerating cellulose are crucial for transforming cellulose into products with added value. Due to the cellulose's inherent amphiphilic characteristics, both its dissolution and the physical and mechanical properties of the regenerated materials can vary depending on the amphiphilicity of solvent used. Innovative solvent designs that offer precise manipulation of these processes are key in developing regenerated materials with specific desired properties. Here we show that modifying the amphiphilicity of superbase-based ionic liquids (SILs) with dicarboxylates allows for the control of the solubility, crystal structure and film-forming capability of cellulose. Notably, the solubility of microcrystalline cellulose (MCC) in the optimized SILs can exceed 10 wt% at 95℃. In addition, regenerated cellulose films (RCFs) with a lower (1-10) crystal plane-oriented structure from SIL solution, using water as coagulation bath, possess not only exceptional mechanical properties (tensile strength: 103.63 MPa, elongation at break: 11.89%), but also transparency (ca. 90% under visible light) and flexibility. We anticipate that the tailored amphiphilicity design of SILs in this study offers a promising and effective solution for dissolution, modification, and reconstruction of cellulose materials.

Keywords: Cellulose dissolution, ionic liquids, superbase, dicarboxylic acids, cellulose films