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Cellulose is a biopolymer with numerous advantages that make it an ecological, economical, and high-performing choice for various applications. To fully exploit the potential of cellulose, it is often necessary to dissolve it, which poses a current challenge. The aqueous zinc oxide/sodium hydroxide (ZnO/NaOH/Water) system is a preferred solvent for its rapid dissolution, non-toxicity, low cost, and environmentally friendly nature. In this context, the behavior of cellulose chains in the aqueous solution of ZnO/NaOH and the impact of temperature on the solubility of this polymer were examined through a molecular dynamics simulation. The analysis of the root means square deviation (RMSD), interaction energy, hydrogen bond curves, and radial distribution function revealed that cellulose is insoluble in the ZnO/NaOH solvent at room temperature (T = 298 K). Decreasing the temperature in the range of 273 K to 268 K led to a geometric deformation of cellulose chains, accompanied by a decrease in the number of interchain hydrogen bonds over the simulation time, thus confirming the solubility of cellulose in this system between T = 273 K and T = 268 K. [ABSTRACT FROM AUTHOR]

Ionic liquids (ILs) and deep eutectic solvents (DESs) are the two most widely used neoteric solvents. Recently, our group described how the simple addition of acetic acid (AcOH) to 1-Ethyl-3-methylimidazolium chloride (EMIMCl) could promote the transition from the original IL to an eutectic mixture of EMIMCl and AcOH. Herein, we studied how cellulose regeneration and EMIMCl recovery from EMIMCl solutions of cellulose could be benefited by the significant differences existing between EMIMCl- and EMIMCl·AcOH-based mixtures and the easy switching from one to the other. Finally, we also demonstrated that the transition could also be accomplished by addition of acetic anhydride and water so that the process could be eventually useful for the achievement of highly acetylated cellulose. [ABSTRACT FROM AUTHOR]

Three alkaline mixtures (NaOH/thiourea, NaOH/urea/thiourea, NaOH/urea/ZnO) and sulfuric acid were used at low temperatures as cellulose solvents, and their cellulose solubility and films' physical properties for bleached chemical wood pulps and cotton linter were compared. Their degree of polymerization (DP) was controlled to 600–800 before dissolution. Among the alkaline solvents, NaOH/urea/ZnO gave the film the highest tensile strength and stretch. When compared to sulfuric acid, NaOH/urea/ZnO gave lower strength properties but higher crystallinity indices in the films. While alkaline solvents could not dissolve the high DP cellulose (DP ~ 2000), sulfuric acid could dissolve the high DP cellulose at below zero Celsius temperature, and the strength properties of the films were not much different from that of the low DP one. It appeared that the low-temperature sulfuric acid treatment did away with the cellulose's DP controlling stage; it decreased cellulose DP very quickly for the high-DP cellulose at the initial stage, and as soon as the cellulose DP reached a DP low enough for dissolution, it began to dissolve the cellulose to result in stable cellulose solution. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]