Single crystals of cellulose IV_II: Preparation and properties

Abstract

Lamellar single crystals of cellulose were obtained from dilute solutions of low‐DP cellulose triacetate, by deacetylation followed by precipitation. At temperatures between 150 and 160°C, pure cellulose IVII crystals were obtained whereas at temperatures between 90 and 150°C, hybrid crystals, having cellulose II and cellulose IVII domains cocrystallized in syntaxy were obtained. In both cases, the crystals were identified and characterized by electron diffraction. When the solutions leading to cellulose IVII were seeded with native cellulose microfibrils, a shish‐kebab structure resulted with the microfibrils decorated by cellulose II lamellae.

Influence of Strong Acid Hydrolysis Processing on the Thermal Stability and Crystallinity of Cellulose Isolated from Wheat Straw

“…However, further treatment procedures, such as bleaching or chemical pulping, are undergone to release the encased cellulose. Hydrolysis techniques, or an activation method [24], tend to remove the amorphous regions, producing glucose monomers [18,25]. The acid specifically targets the amorphous regions, due to the disorder and voids present there, whereas the more ordered regions tend to lack these voids [20].…”

Packing analysis of carbohydrates and polysaccharides. 16. The crystal structures of celluloses IVI and IVII

“…This is certainly true for the polymorphs that can be grown in single crystal form, such as cellulose 11 and IVll (18). The possible exception may be Valonia cellulose which appears to crystallize in an eightchain unit cell, although an alternative, two-chain, triclinic cell has been proposed (21).…”

“…Cellulose IV,, was predicted to reside in a reasonably deep energy minimum, which also agrees with experimental facts. Among the latter is the observation that single crystals of cellulose grow in the cellulose IV,, lattice at high temperatures rather than in the cellulose 11 lattice which occurs at low temperatures (18). In addition, it has been shown that cellulose lVll can be converted to cellulose 11, but only through a drastic treatment of boiling in hydrochloric acid (2).…”

Pharmaceutical significance of cellulose: A review

“…Cellulose II, generally occurring in marine algae, is a crystalline form that is formed when cellulose I is treated with aqueous sodium hydroxide [42][43][44]. Among the four different crystalline polymorphs cellulose I, II, III, and IV, cellulose I is thermodynamically less stable while cellulose II is the most [45][46][47], and the heating of cellulose III generates cellulose IV crystalline form [48]. Figure 2 shows the transformation of cellulose into its various polymorphs [49].…”