Method of obtaining cellulose diacetate with a pregiven chiral structure for highly efficient materials

The physicochemical properties of 16 laboratory and 9 commercial samples of cellulose diacetate (CDA) of standard (3 wt%) and high (3.5–40 wt%) humidity, their solutions in acetone and an acetone–water mixture with component ratios of 95:5–99.5:0.5 were studied. Samples were taken at the polymer drying stage after wood pulp acetylation under heterogeneous conditions, followed by saponification in an alkaline medium. It was established that high-humidity CDA differed from the standard sample by an amorphized structure, improved solubility with almost the same numerical values of the size and concentration of supramolecular particles, turbidity, viscosity and viscous flow activation energy. The chiral structure of high-humidity CDA differed significantly from the polymer of standard humidity, which was confirmed by a change in the values and sign (from positive to negative) of the specific optical rotation in solution. Changes in humidity by means of polymer hydration in water or in steam within 20–100 °C, as well as water addition to an acetone solution of standard CDA, almost did not affect the stereomeric organization of the cellulose ester. The following were prepared from the CDA with high humidity and, accordingly, a modified chiral structure: fibers with improved physico-mechanical characteristics; membranes capable of purifying blood plasma from cholesterol while saving proteins and electrolytes; films with high selectivity and hydrodynamic permeability; and filter sorbents with a high degree of retaining the harmful components of tobacco smoke. It has been suggested that obtaining high-humidity CDA can be considered as an alternative method of obtaining acetic cellulose ester with a pregiven chiral structure to manufacture highly efficient materials, including those with novel functional properties.