Kovalchuk A. Synthesis, structure and properties of core-fluorinated isomeric polyazomethines containing azo groups

Object of research: Perfluoroaromatic azo-and azomethine-containing monomers and polymers. Aim of the work: development of methods of synthesis of corefluorinated of azo-containing monomers of the isomeric structure and obtaining on their basis polyazomethines with azo groups in their composition and fragments of tetrafluorobenzene or octafurobiphenyl, establishing a connection between the chemical structure, structure and properties of the resulting compounds. Methods: 1Н, 19F,13С NMR, IR, UV-vis spectroscopies, The Matrix-Assisted Laser Desorption Ionization – Time of Flight mass spectrometry (MALDI-ToF МS), wide angle X-ray diffraction, mechanical analysis, differential scanning calorimetry, thermogravimetric analysis, polarization-optical microscopy, experimental optical circuits based on laser installations. To obtain Azo-Pam with the azo groups in the main chain there was developed a method of synthesis of tetrafunctional reactive isomeric azo-containing bis-hydroxybenzaldehydes, containing perfluorinated mono- or biphenylene units. The synthesised monomers are stimuli-responsive and change their optical properties within a wide range due to the external factor influence (UV-irradiation, a concentration, pH or solvent polarity change). By means of the interaction between core-fluorinated azo-containing bis-hydroxybenzaldehydes with 1-aminohexane and hexamethylenediamine there were the model azo-azomethine containing chromophores and Azo-Pam of diphilic type obtained. According to WAX and DSC para-isomeric Azo-Pam are characterised by stratified amorphous-crystal structure, their Tg makes up >300 °C, whereas meta-isomeric Azo-Pam have an amorphous structure with Tg ~134 °C. All obtained polymers are thermostable till 350 °C. It was found out that the irradiation of meta-substituted Azo-Pam polymer films lead to the emergence of anisotropic properties due to trans-cis isomerization of the azo groups. On the basis of the meta-isomeric Azo-Pam film with octafluorobiphenyl units the ability to record diffractional gratings and orientate a nematic liquid crystal by it was demonstrated. Polymer systems, based upon core-fluorinated Azo-Pam, are promising as polarization susceptible materials used in holographic methods for recording, storage and reproduction of optical information and nematic liquid crystal orientation.