Dynamic Segment Size of the Cellulose Chain in an Ionic Liquid

Cellulose dissolution in diallylimidazolium methoxyacetate + N-methylpyrrolidinone mixture

The utilization of cellulose in industrial applicat is of great significance to sustainable development of human society and reducing dependence on dwindling fossil resources. Nevertheless, this utilization of cellulose has actually been limited due to its insolubilization. Here, novel solvents consisting of diallylimidazolium methoxy acetate ([A₂im][CH₃OCH₂COO]) and N-methylpyrrolidinone (NMP) were developed. The solubility of cellulose in [A₂im][CH₃OCH₂COO]/NMP was determined, and the influence of [A₂im][CH₃OCH₂COO]/NMP molar ratio on cellulose dissolution was systematically investigated. Meanwhile, we also presented the affecting factors of the cellulose material fabrication including preparation approach, [A₂im][CH₃OCH₂COO] and cellulose solution concentration. Attractively, the [A₂im][CH₃OCH₂COO]/NMP solvents display much powerful dissolution capacity for cellulose even at 25 °C (25.4 g 100 g⁻¹). This is mainly ascribed to the combined factors: The hydrogen bond interactions of the H2, H4 and H6 in [A₂im]⁺ and carboxyl O atom in [CH₃OCH₂COO]⁻ with the hydroxyl H atom and O atom in cellulose; the dissociation of NMP towards [A₂im][CH₃OCH₂COO]; the stabilization of NMP towards the dissolved cellulose chains. In addition, the thermostability and chemical structure of the regenerated cellulose from the solvents was also estimated.

Dissolution performance of cellulose in [A2im][MOA]/MIM solvents

Cellulose solvents ([A2im][MOA]/MIM) were developed by combining diallylimidazolium methoxyacetate ([A2im][MOA]) with N-methylimidazole (MIM). The cellulose solubilities in the ([A2im][MOA]/MIM) solvents were determined at 25 °C, and the effect of the MIM/[A2im][MOA] molar ratio on cellulose solubility was systematically investigated. Attractively, the solvents show cellulose solubility as high as 25.2 g 100 g-1 even at 25 °C. It is proposed that the H2, H4 and H6 in [A2im]+ and the carboxyl O atom in [MOA]- primarily contribute to the dissolution of cellulose; MIM mainly acts to dissociate [A2im][MOA] into [A2im]+ and [MOA]-, and stabilize the dissolved cellulose chains. Moreover, the porous cellulose materials with varying morphological structures could be tailored by simply tuning the cellulose solution concentration, and the formation mechanism of the cellulose material was discussed.

Development of Diallylimidazolium Methoxyacetate/DMSO (DMF/DMA) Solvents for Improving Cellulose Dissolution and Fabricating Porous Material

Cellulose is the most abundant natural biopolymer, with unique properties such as biodegradability, biocompability, nontoxicity, and so on. However, its extensive application has actually been hindered, because of its insolubility in water and most solvents. Herein, highly efficient cellulose solvents were developed by coupling diallylimidazolium methoxyacetate ([A₂im][CH₃OCH₂COO]) with polar aprotic solvents dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), and N,N-dimethylacetamide (DMA). Attractively, these solvents showed extraordinarily powerful dissolution performance for cellulose (e.g., 26.1 g·100g⁻¹) in [A₂im][CH₃OCH₂COO]/DMSO(R_DMSO = 1.01 solvent even at 25 °C), which is much more advantageous over previously reported solvents. To our knowledge, such powerful cellulose solvents have not been reported before. The cellulose dissolution mechanism is proposed to be of three combined factors: (1) The hydrogen bond interactions of the H2, H4 and H6 in [A₂im]⁺ and the carboxyl O atom in [CH₃OCH₂COO]⁻, along with the hydroxyl H atom and O atom in cellulose, are main driving force for cellulose dissolution; (2) the dissociation of [A₂im][CH₃OCH₂COO] by DMF increases the anion and cation concentrations and thus promotes cellulose dissolution; (3) at the same time, DMF also stabilizes the dissolved cellulose chains. Meanwhile, the porous cellulose material with a varying morphologic structure could be facially fabricated by modulating the cellulose solution concentration. Additionally, the dissolution of cellulose in the solvents is only a physical process, and the regenerated cellulose from the solvents retains sufficient thermostability and a chemical structure similar to the original cellulose. Thus, this work will provide great possibility for developing cellulose-based products at ambient temperatures or under no extra heating/freezing conditions.

Solid-state fluorescent composite phosphor based on cellulose grafted with carbon dots for temperature sensing

Blue phosphors consisting of cellulose and carbon dots (CDs) have been prepared successfully for the first time, which show excellent fluorescent temperature sensing properties.