Super solvent of cellulose with extra high solubility for tunable cellulose structure with versatile application.

Low-temperature two-step concentrated H 2 SO 4 was discovered to be a solvent with high cellulose solubility [>300 g/L (17 wt%)], fast cellulose dissolution, high regeneration yield (>0.92 g/g), and cellulose being mouldable during regeneration. The superior performance was enabled by the much better compatibility of cellulose with lower concentrated H 2 SO 4 at low temperature, compared with that of high concentrated H 2 SO 4. The regenerated cellulose was characterized by mostly unchanged composition and highly tunable degree of polymerization (DP). The H 2 SO 4 starting content, cotton fibre temperature, dissolution temperature, regeneration temperature, regeneration bath and storage time were factors determining the DP of regenerated cellulose, which could be equivalent to 4–90 % of the original cotton. These advantages of the solvent enabled versatile application in fabrication of extra strong cellulose hydrogels, manufacture of strong cellulose fibres, preparation of various homogenous composites which would be prepared with much more difficulty by using other solvents, and facile manufacture of cellooligosaccharides. [Display omitted] • Cellulose fast dissolved with no crystal structure in 68 % H2SO4 (≤0 °C). • High cellulose solubility (>300 g/L) was achieved in low-temperature H 2 SO 4. • High cellulose regeneration yield was achieved (as high as 0.97 g/g). • Highly tunable cellulose structure in the low-temperature H2SO4 dissolution process • Cellulose hydrogel, fibre, homogenous composites, and oligosaccharides were prepared. [ABSTRACT FROM AUTHOR]