Browsing by Author "Atanasov V."
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Item PREPARATION AND CHARACTERIZATION OF BIODEGRADABLE POLYMERIC NANOCOMPOSITES BASED ON POLYLACTIDE AND GRAPHENE OXIDE(2020-01-01) Velev P.; Samichkov V.; Atanasov V.; Tsvetanov K.A homogeneous dispersion had been prepared with a concentration of 1 % nanosized graphene oxide in ammonium hydroxide. In a simple mixer, the polylactide granulate was homogenized with varying amounts of nanosized dispersion and then dried to a constant mass. From the so-treated granulate test specimens were prepared using injection molding. The resulting nanoparticles containing graphene oxide in concentrations of 0.01, 0.05 and 0.1 % were characterized by tensile strength and elongation at break, infrared spectroscopy, dynamic mechanical thermal analyzer, X-ray diffraction, scanning electron microscopy (SEM). The results show that nanocomposites are homogeneous enough, having in mind their preparation method. Their physicomechanical characteristics are some lower than those for pure polylactide. These types of composites could find an application as a nutrient medium for definite bacterial strain.Item Synthesis, characterization and spectroscopic properties of some 2-substituted 1,3-indandiones and their metal complexes(2009-07-10) Ahmedova A.; Atanasov V.; Marinova P.; Stoyanov N.; Mitewa M.New 2-acyl-1,3-indandione derivatives, compounds 1-4, were obtained by condensation of 2-acetyl-1,3-indandione with benzaldehyde, thiophene-2-aldehyde, thiophene-3-aldehyde and furane-2-aldehyde, respectively. The structures of the newly synthesized 2-substituted 1,3-indandiones were characterized by means of spectroscopic methods (FT-IR, 1H and 13C NMR, UV-Vis and MS). Based on the obtained results it is suggested that the compounds exist in the exocyclic enolic form. Mass spectral fragmentation paths are also proposed. In order to verify the possibility for tautomerization processes of the newly synthesized compounds their absorption spectra were recorded in various solvents. Furthermore, the complexation properties of the compounds with metal(II) ions were also studied. A series of non-charged complexes with Cu(II), Cd(II), Zn(II), Co(II) and Ni(II) was isolated and analyzed by elemental analyses and IR. The paramagnetic Cu(II) complexes were studied by EPR and distorted, flattened tetrahedral structures are predicted. The other metal complexes show the presence of water molecules, most probably coordinated to the metal ion, thus forming octahedral geometry. Ultimately, the studied properties of the newly synthesized compounds, 1-4, suggest that they may find application as extracting agents for metal ions, rather than as optical sensors. © Versita Warsaw and Springer-Verlag Berlin Heidelberg 2009.Item Two dimensional polymerization of graphene oxide: Bottom-up approach(2015-08-01) Atanasov V.; Russev S.; Lyutov L.; Zagraniarsky Y.; Dimitrova I.; Avdeev G.; Avramova I.; Vulcheva E.; Kirilov K.; Tzonev A.; Abrashev M.; Tsutsumanova G.We demonstrate a bottom-up synthesis of structures similar to graphene oxide via a two dimensional polymerization. Experimental evidence and discussion are conveyed as well as a general framework for this two dimensional polymerization. The proposed morphologies and lattice structures of these graphene oxides are derived from aldol condensation of alternating three nucleophilic and three electrophilic centers of benzenetriol.