Enthalpies of dilution of aqueous solutions of aliphatic 6,12- and 12,12-ionene bromides and fluorides and enthalpies of mixing with low molecular-weight salts, such as Naf and NaBr, are determined. The comparison with theoretical results, based on the Poisson–Boltzmann cell model, is presented. The theory predicts for the enthalpy of dilution to be exothermic and the enthalpy of mixing endothermic, while experiments show that signs of the heat effects depend on the nature of the counterion of the added salt, as also on the hydrophobicity (numbers x, y of methylene groups) of the ionene.
B.05 Guest lecturer at an institute/university
COBISS.SI-ID: 1681967The aim of the project was modernization of the content and the methods of the learning processes according to the development of science and learning techniques. In the lecture the contents and the problems of the international chemistry olympiads were presented; these exceed sometimes to a high extent the usual knowledge of the students. Lecture was intended for education of the chemistry teachers to possibly implement some of these advanced contents into modern curricula.
D.10 Educational activities
COBISS.SI-ID: 1676079The structure of aqueous solutions of polysaccharide levan of various bacterial origins has been investigated based on the SAXS and dynamic rheological measurements. For this purpose the levan has been isolated from the biofilm of bacteria Bacillus subtilis and also commercially available levans from bacteria Zymomonas mobilis and Erwinia herbicola have been used. SAXS results were evaluated based on the string-of-beads model that provided an insight to the conformational properties of the levan molecules. The results of the dynamic rheological results revealed interesting viscoelastic properties of these solutions already at very low polymer concentrations.
B.03 Paper at an international scientific conference
COBISS.SI-ID: 1627183First approaches in calculation of electric conductivity of solutions containing electrically charged particles were based on the calculation of the electric potential on the shear plane (zeta-potential). This plane divides surrounding solution from the electrokinetic entity composed of highly electrically charged particle and its Stern layer. In later theories z potential was gradually losing its importance in calculation of mobility of electrically charged particle. We carried out calculations for the case of typical representative of spherical polyion and for the case of linear polyion and show that it is possible to qualitatively, if not in some cases also quantitatively, forecast conductivity of solutions containing highly charged particles by taking into account z potential and fraction of free counterions. Following this approach it is possible in many cases better forecast conductivity of polyelectrolyte solutions than by the existing and more renowned theories.
B.03 Paper at an international scientific conference
COBISS.SI-ID: 1626415