Dissolution and regeneration of cellulose using superbase-based dicarboxylic ionic liquids with tailored amphiphilicity

A series of SILs containing dicarboxylate anions were synthesized via a solvent-free one-step method. By adjusting the amphiphilicity of the anionic and cationic components within the SILs, the dissolution performance of cellulose can be effectively modulated, enabling it to surpass a 10 wt% dissolution capacity for microcrystalline cellulose. Beyond dissolution, fine-tuning SIL’s amphiphilicity could control the network and crystalline structure of obtained regenerated cellulose films in water, enabling the creation of cellulose films with excellent properties. [Display omitted] •Straightforward and efficient SIL preparation via a solvent-free one-step method.•SIL’s amphiphilicity precisely controls the dissolution and regeneration of cellulose.•Regulating the amphiphilicity of SILs achieves cellulose dissolution exceeding 10 wt%.•Suitable amphiphilicity of SILs enhances the properties of obtained regenerated cellulose films. 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 °C. 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.