ИСТИНА

Design and preparation of liquid crystalline (LC) composites is one of the hot topics in modern materials science. An intensive activity in this field is associated with a wide range of possible applications of such “smart” materials predetermined by the combination of unique optical properties of LC systems with specific features of optical and mechanical properties of the different matrices. This report describes our results on the design and investigation of hybrid composites based on two types of polymer matrices and porous inorganic matrix: (i) porous polyolefines (polyethylene or polypropylene), (ii) porous cholesteric polymer networks and (iii) one-dimensional photonic crystals based on porous silicon. Filling these matrices with low-molar-mass photochromic LC mixtures or LC copolymers enables one to obtain composites with photovariable optical properties. In the first type of the composites, the highly anisotropic porous structure of polyolefin films provides uniaxial alignment of the nematic phase inside the pores. UV and visible light irradiation enables the dichroism, birefringence and polarized fluorescence photocontrol in the obtained LC composite films. The second type of the polymer scaffolds is prepared by the photopolymerization of the cholesteric mixtures containing mesogenic mono- and diacrylates followed by removing the low-molar-mass components that allows obtaining a highly porous cholesteric networks. Filling these scaffolds with photochromic LC mixtures capable of the isothermal photoinduced phase transition from nematic to isotropic state results in cholesteric films with phototunable position and width of selective light reflection peak. For the LC composites based on the porous cholesteric networks filled with azobenzene-containing LC copolymer the possibilities of transmission and reflection holographic gratings recording are demonstrated. The third type of the composites presents photosensitive one-dimensional photonic crystals based on electrochemically etched porous silicon filled with low-molar-mass photochromic LC mixtures (Fig. 1) or copolymers. Irradiation of these composites with non-polarized or polarized light induces a reversible shift of photonic stop band spectral position or modification of its shape. LC hybrid composites based on organic and inorganic porous matrices obtained and studied in this work can be considered as promising materials for the applications in photonics and optoelectronics. Acknowledgements: This research was supported by the Russian Foundation for Basic Research (19-03-00337, 19-53-26007) and Russian Science Foundation (19-13-00029).