ИСТИНА

The development of new types of “smart” materials and investigations of their properties are the most challenging fields of modern science. One of the most promising substances designed in order to obtain smart materials are dendrimers, high-molecular mass compounds having superbranched molecular structure predetermining their unique physico-chemical properties. In the present work, for the first time, the influence of molecular structure and generation number of photochromic LC dendrimers with azobenzene terminal groups (Fig. 1) on the photoorientation processes induced by polarized light was studied [1]. Irradiation of the dendrimer films by polarized UV and visible light induces uniaxial orientation of azobenzene groups in direction perpendicular to the polarization plane of the incident light. It is shown that smectic or columnar phase formation enables to stabilize photoinduced order even at temperatures above the glass transition. Unusual dependence of the generation number on the values of photoinduced dichroism was found (Fig. 2). For the dendrimers of low generations (1st-3rd) an increase in generation number leads to a decrease in photoinduced dichroism, whereas for the dendrimers of 4th and 5th generations very high values of dichroism were revealed. These values are comparable with the dichroism for the azobenzene-containing side chain polymers studied before [2]. Possible explanations of the observed peculiarities based on the spectral data, difference in phase behaviour and aggregation phenomena are suggested. Possibilities of the optical image photorecording on the films of the photochromic LC-dendrimers were demonstrated (Fig. 3). Obtained results allow one to consider photochromic LC dendrimers as promising materials for applications in optics, optoelectronics and photonics. This research was supported by the Russian Science Foundation (14-13-00379). References [1] A. Bobrovsky, N. Boiko, V. Shibaev, Polymer, 2015, 56, 263-270. [2] V. Shibaev, A. Bobrovsky, N. Boiko, Prog. Polym. Sci., 2003, 28, 729-836.