Synthesis and Sulfation with Sulfamic Acid of Aerogels Based on Birch-Wood and Cotton Celluloses

Firstly, the structure and properties of cellulose aerogels produced from birch-wood and cottoncellulose and of, and products of their sulfation with a non-toxic sulfamic acid-urea complex in an environmentally safe solvent - a mixture of polyethylene glycol and sodium hydroxide are compared. Aerogels based on birch and cotton celluloses have similar values of apparent density (0,071-0,078 Gamma/CM3) and porosity (near 95 %). The products of sulfating of cellulose aerogels, in contrast to the originalbirch and cotton celluloses. are completely soluble in water. Their yield and degree of substitution are higher when using birch cellulose aerogel. By drying the dissolved products of sulfating of cellulose aerogels, smooth and transparent films were produced. The structure and morphology of the obtained aerogels and films were established by metods of scanning electron microscopy and atomic force microscopy. Birch cellulose aerogel (BCA) has a reticular microfibrillated porous structure, and cotton cellulose aerogel (CCA) has a spongy structure in which more cavities and cracks are observed than in the case of CCA. The surface of the film of sulfated BCA is formed by particles with a length 100-200 nm and width of 50-70 nm, and the films of sulfated CCA is formed by spherical particles with a diameter of 70-100 nm. The developed methods for obtaining sulfated cellulose films can be used in medicine to oreate anticoagulant coatings.