Příprava a charakterizace antibakteriálních nanokompozitů

Abstract

The dissertation thesis deals with characterization of new forms of antibacterial composites prepared based on natural clay materials montmorillonite and vermiculite. The clay minerals as a matrix firmly hold nanoparticles of copper and silver that means that are not dangerous for the environment. In the first part of the work, natural clay minerals, vermiculite and montmorillonite with different negative surface charge and their forms after cation exchange Na-montmorillonite and Na-vermiculite were chosen as clay matrix for silver and copper. Aqueous solutions of silver and copper nitrate served as source of silver and copper ions. Prepared powder samples were characterized by analytical methods. Elemental analysis showed differences between silver and copper content which depend on the negative layer charge of clay mineral, type of interlayer cation and different way of silver and copper binding on the carrier. The structure changes of minerals after silver and copper nitrate action and removing of nitrate ions by washing with water were studied by X-ray diffraction. The changes in the basal diffraction profiles of clay minerals confirmed the presence of silver and copper in the interlayer space. Morphology of vermiculite particles was studied by scanning electron microscopy. Good stability of elements on phyllosilicate carriers was confirmed by test of stability at aqueous medium. Test of antibacterial effect of Ag,Cu-montmorillonites and Ag,Cu-vermiculites showed positive effect on inhibition of growth of Gram-positive (G+) and Gram-negative (G-) bacteria strains. In the second part of the work, the selected vermiculite samples were modified by organic compounds (dodecylamine and hexadecyltrimethylammonium bromide) using solid-solid melt intercalation and were used as nanofillers in polymer matrix. The powder nanofillers and composite materials were characterized using X-ray diffraction, which confirmed formation of nanocomposite structure mainly in polyethylene/organo-vermiculites with higher organic content. Change in polyethylene matrix structure was evaluated by scanning electron microscopy. Nanofiller distribution in matrix was observed by light microscopy. Creep test of selected samples proved the reinforcement effect of nanofillers in polyethylene. The testing of antibacterial activity showed positive effect of prepared materials on growth inhibition of G+ and G- bacteria.