Kuzema P. Properties of chemically modified high-disperse silicas with hydrophilic-hydrophobic surface

Subject of study: chemical modification of high-disperse oxides and its influence on physicochemical properties of these oxides. The aim of research is to study the influence of methylsilylation degree of fumed silica surface on wetting and structurization processes in polar and non-polar media (water and decane, respectively) as well as on immobilization of vitamin B1 from aqueous medium. Methods of investigation: IR spectroscopy, temperature-programmed desorption mass spectrometry, molecular mechanics and quantum chemistry, gas-phase adsorption and adsorption from solutions, microcalorimetry, capillary impregnation of liquids, rheology and structural mechanics. The character of chemical processes passage occurring while synthesis of methylsilylated silicas with hydrophilic-hydrophobic surface and thermal destruction of methylsilyl coverage was concretized. Dependence of rate of dimethyl- and trimethylsilylated silicas wetting by water and decane upon the degree of surface modification was determined.The changes of structrural-mechanical and rheological factors of modified silica dispersions in water and decane depending on the degree of surface methylsilylation were studied. The vitamin B1 adsorption on partially dimethyl- and trimethylsilylated silicas depending on acidity of aqueous medium, degree of modification and the type of methylsilyl coverage as well as the process of thermal decomposition of this vitamin adsorbed on carriers involved were investigated.