Liquid-crystalline polymer systems: From the past to the present

In the first part of this review, in a brief historical perspective, we consider the evolution of the scientific activity of Nikolai Al’fredovich Platé, Academician of the Russian Academy of Sciences: from grafted polymer systems to comb-shaped and liquid-crystalline polymers. The main biographical data on Platé are related to his scientific work at Moscow State University, and his research-development strategy to create and study of LC polymers with comb-shaped structure is considered. The second part of the article is devoted to discussion of scientific directions in this area that were developed in the last five years at the Laboratory of Chemical Transformations of Polymers, where Platé started his scientific activity. Special attention is paid to the research data on photochromic liquid-crystal polymers and composites. A concept of the preparation of multifunctional comb-shaped LC polymers containing mesogenic, photochromic, and chiral groups, as well as functional (crown ether) fragments, is presented. The photo-orientational processes occurring in photochromic LC polymers, which were used to prepare “command” surfaces and photo-orientators, are considered in detail. The preparation of a new class of photochromic polyamides with azobenzene, cinnamoyl and coumarin groups, which have been proposed for the obtaining of polymer films with latent data recording, is described. The phase behaviors and photo-optical properties of synthesized photochromic triple LC block copolymers are reported. Examples of holograms based on cholesteric LC blends, which allow double recording on the same polymer film, are presented. The results of investigations of light-controlled cholesteric polymer-stabilized LC networks with crown ether fragments in the compositions of macromolecules that are able to form complexes with metal ions are presented. The methods of preparation of photocontrolled and electrically controlled polymer LC nanocomposites with nanoparticles, as well as research data on their photo-optical properties, are considered.