Siberian Federal University

The structure of sodium salts of arabinogalactan (AG) sulfates, obtained by sulfation of AG with sulfamic acid – urea mixture in the homogeneous medium of dimethyl sulfoxide (DMSO) was studied for the first time. According to thermal analysis (TA) data, the onset temperature of thermal decomposition of sulfated AG is 218 °C, and that of the initial AG is 235 °C. The quantitative characteristics of the kinetics of the main stage of sample pyrolysis were determined using the Coates-Redfern method. It was found that the activation energy of AG is 150 kJ/mol, whereas with the introduction of sulfate groups the activation energy decreases to 35 kJ/mol. The XRD method shows that the amorphization of arabinogalactan structure occurs during it`s sulfation. With the use of SEM method, it was found that the morphology of the obtained arabinogalactan sulfates differs from the morphology of the initial arabinogalactan. The initial AG consists mainly of globular particles with size of 10–90 μm, while sulfated AG – of spherical particles with a diameter of 1–10 μm. According to AFM data, the surface of film of arabinogalactan sulfates is formed by the rather homogeneous spherical particles with an average diameter of 50 nm and does not contain any impurities in its phase composition