Borodavka T. Adsorption and chemical transformations on silicas surfaces, modified by chitosan

The thesis is devoted to the studying of the interaction of chitosan with the fumed silica surface, investigation of adsorbed polymer layer structure and influence of the silica surface modification by chitosan on its adsorption properties to iodine and rutoside venorutone. The adsorption/desorption of chitosan on the fumed silica surface was investigated. Analysis of the morphology and structural characteristics of chitosan modified fumed silica, silica/titania and silica/alumina were performed. Thermolysis of chitin, chitosan and chitosan adsorbed on the fumed silica was investigated using temperature-programmed desorption mass spectrometry (TPD MS). Stages that correspond to the thermolysis of acetylated and deacetylated segments of the polymer chain were determined. Approach for the estimation of deacetylation degree based on TPD MS data was suggested. Stages which relate to the thermolysis of non-connected segments of adsorbed chitosan (loops, trains) and segments directly connected to the silica surface were defined. The correlation of adsorbed chitosan amount and p parameter value was obtained. It was revealed that with the increasing of polysaccharide amount the p parameter decreases from 0,4 to 0,1. The hemolysis test indicates that biocompatibility of the fumed silica modified by chitosan increases by an order compared to the initial oxide. It was shown a feasibility of creating of materials of biomedical assignment on the base of supramolecular complexes between polysaccharide and biologically active molecules on the fumed silica surface.