The dissertation is devoted that polymer NLO nanocomposite materials filled with flavonol-type chromophores are promising materials for various applications in photonics and optoelectronics, and their study is relevant and of both scientific and practical interest.The thesis deals with the creation of cross-linked epoxy polymer nanocomposites with nonlinear optical (NLO) properties based on diglycidyl ether of bisphenol doped by chromophores flavone type. The optical, thermal, morphological authorities on nonlinear optical parameters of epoxy nanocomposites was investigated and the optimal filler concentration with which the NLO activity of such materials does not reduce was found.
In the thesis for the first time, polymer materials with high nonlinear-optical activity based on epoxy polymer doped by natural flavones (quercetin, fizetin), and chemically modified natural flavone (sulfoquercetin) were obtained.
With of UV-vis spectroscopy and a scanning electron microscopy, it was found that the molecules of flavones, under the conditions of synthesis of the polymer matrix of the filler molecule, exist in at least two forms: neutral and anions. Quantitative redistribution between these two forms with increasing concentration of filler in the polymer matrix leads to different positions of the resulting maximum on the spectral curves.
The performed quantum-chemical calculations of molecular hyperpolarizability (β) showed that the greatest value of this parameter has quercetin (β = 108,2×10-40 m4/V). Therefore, in this work for increase the NLO activity of the filler, a chemical modification of quercetin was developed due to the introduction of its chemical structure of the sulfogroup, which by its nature has a Hydrogen acceptor, and therefore will contribute to increasing the NLO activity of the chromophores at the molecular level. Using IR spectroscopy and 13C NMR spectroscopy, it has been proved that the modification occurred in the C8 position of the quercetin molecule.
It has been found that due to the chemical modification of quercetin by introducing a sulfo group in the C8 position of the chromophore molecule filler exist in ionic form. It was shown for the first time that such chemical modification of quercetin leads to an increase the chromophores hyperpolarization and in turn leads to increase the macroscopic NLO properties of polymer materials due to the aggregation of filler ions.
The dependence of second order macroscopic polarizability (χ(2)) of polymer nanocomposites with quercetin and sulfoquercetin on filler concentration was established. It was shown that such a dependence for polymer nanocomposites with quercetin is of extreme nature. That is, the value of χ(2) at the filler concentration 30 wt. % is maximal. A chromophore concentration increase leads to decrease values of the parameter χ(2). On the other side, an increase of the sulfoquercetin concentration (up to 50 wt. %) in the polymer matrix results in an increase of the value of χ(2). This fact indicates that an increase of the ion chromophores agglomerates size is more conducive to dipole orientations under the influence of polarization under the action of a corona discharge current than the chromophore molecules in a neutral form.
The effect of the concentration of these chromophores in a polymer matrix on properties such as spectral, thermophysical, structural properties was investigated of certain exploitation properties that are determinant for materials used in photonics and optoelectronics. The carried out researches give the possibility of effective use of epoxy polymers doped by flavanol type chromophores in various NLO applications in photonics and optoelectronics.
Key words: epoxy polymers, flavones, nonlinear optical activity, polymer composition materials, photostability
