We have shown that hyperbranched (HB) polyesters based on 2,2-bis(methylol)propionic acid, which are amorphous materials, develop during annealing a microstructure of different degree of ordering that influences their thermal and rheological properties. The importance of the results of this study is understanding the relation between the hyperbranched structure and the properties of commertially available hyperbranched polyesters. The importance of the mentioned results is reflected in many invited and key-note lectures at international and national scientific conferences, and citations.
COBISS.SI-ID: 3262490
The article describes the development of the methodology for absolute molar mass determination of hyperbranched (HB) polyesters by size exclusion chromatography coupled to a multi-angle light scattering (SEC-MALS) assisted by NMR and DSC. HB polyesters are soluble on a molecular level only if they are thermally pre-treated by heating at 140 °C, then submerged into liquid nitrogen and immediately dissolved in a solvent. The knowledge of their average molar masses and distributions as well as their structural characteristics is highly important for the understanding of their properties.
COBISS.SI-ID: 2983962
The microstructure of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) copolymers (PHBV) and mixture of two PHBV was studied by 13C NMR and ESI-MS. The results of both methods were in good agreement. We also studied the influence of microstructure on PHBV thermal properties. Complex melting transition indicates that PHBV are the mixtures of copolymers with broad comonomer distribution. The results demonstrate complementary of both methods for microstructure determination and influence of microstructure on the thermal properties of PHBV copolyesters.
COBISS.SI-ID: 3544346
For the first time we described the formation of Cu2O nanowires (NW) during the reduction of Cu(II) acetate in di(ethylene glycol). The chemical composition is confirmed by FTIR and powder X-ray diffraction (XRD) while the NW structure is confirmed by scanning and transmission electron microscopy (SEM, TEM) and selected-area electron diffraction (SAED). The reaction mechanism of Cu2O NW formation through copper glycolates was proposed. The importance of this achievement is in the defined conditions of the Cu2O NW formation which is a basis for their further research and practical application.
COBISS.SI-ID: 3645978
We present a theoretic study of causes for microwave effects on the chemical reaction, which often leads to different products than at classical convection heating. The hypothesis used was that microwaves cause selective excitation of solvent assemblies that transfer the energy through collisions resulting in a non-equilibrium increase of rotational energy of the system meaning that rotations are formally at a higher temperature than other modes of motion. The hypothesis was supported with the use of computer simulations for the case of ester hydrolysis in comparison to experimental results.
COBISS.SI-ID: 3846938