Liquid-crystalline polymers: Past, present, and future

The main steps of the evolution in studies related to the design and investigation of the structure and properties of thermotropic LC polymers containing mesogenic groups are discussed. The principal attention is focused on the results of experiments performed at the Laboratory of Chemical Transformations of Polymers, Faculty of Chemistry, Moscow State University, which was established and guided by Academician N.A. Platé from 1966 to 1985 and then supervised by V.P. Shibaev, the author of this review. Historical evidence is presented to demonstrate the contribution of Russian scientists to the development of approaches to the synthesis and study of chiral and electro- and photocontrollable comb-shaped LC polymers and related composites. The concept of preparing multifunctional LC copolymers and LC networks containing mesogenic, chiral, photochromic, and functional (including ionophoric) groups that can undergo hydrogen bonding, form complexes with metal ions, and interact with nanoparticles is scrutinized. Specific features of the structural organization of polymer mesophases are covered. The data on multifunctional comb-shaped LC polymers, LC ionomers, and LC dendrimers are examined, and the problems concerning the design of light-controllable LC copolymers and polymer photochromic composites and networks are reviewed. Some applied aspects of using LC polymers are considered: specifically, approaches to creation of lasers based on cholesterics and photo- and electroactive media in optics and photonics, systems for data recording and storage, holography, display technology, and other fields.