Fivefold Helical Cellulose Trapped in a Sulfuric Acid Framework

A sulfuric acid aqueous solution effectively dissolves cellulose at a concentration of 64 wt % when it is precooled ?20 °C. Although this low-temperature has high potential as an solvent, the molecular detail its swelling and dissolution mechanism not known. In study, we followed behavior in using X-ray diffraction found crystalline complex structure, molecules are organized similar manner to those tetrahydrate crystal. Cellulose adopt rare fivefold helical conformation, their hydroxyl groups participate hydration acid. This complexation acid-concentration dependent occurs only above 62 %, indicating that deficiency number water around drives recruit form stable tetrahydrate-like state. It swells opens structure without completely destroying order, can be confirmed by partial reversibility regenerate I.