V.P. Shibayev

Structure of thermotropic liquid crystalline polymers with cyano-containing mesogenic groups☆

The paper gives the results of the X-ray structural investigation of liquid crystalline polyacrylates and polymethacrylates whose side branches contain cyano-substituted aromatic azomethine and cyanodiphenyl mesogenic groups. It was found that these polymers form liquid crystalline phases of nematic, smectic A and smectic C types. Molecular models for the liquid crystalline phase structures are proposed on the basis of an analysis of texture X-ray patterns.

Structure and properties of liquid crystal polymers containing cholesterol

Abstract An investigation has been made of the structure and properties of cholesteryl esters of poly-N-methacryloyl-ω-aminocarboxylic acids differing in the length, n , of the pendant alkyl substituent (PChMAA- n ) and copolymers of ChMAA- n with n-alkylacrylates and n-alkylmethacrylates. The effect of the length of the methylene chain linking the cholesterol groups with the main chain has been considered, as well as the frequency with which the cholesterol groups are positioned in the structure and the properties of the polymers under investigation. It has been shown that, when the number of methylene links in the pendant alkyl radical, n , is greater or equal to 5, the polymers form a liquid crystal (LC) phase in the glassy, highly elestic and viscous low conditions. Schemes for the packing of the macromolecules of the polymers containing cholesterol in the LC condition are put forward.

Ferroelectric liquid crystalline polymethacrylates

Abstract A new approach to the synthesis of ferroelectric polymers is proposed, based on the appearance of spontaneous electric polarization in the chiral smectic phase C of liquid crystalline polymers. Synthesis, phase transitions, structure, and ferroelectric properties are described for the first representatives of such polymers.

Thermotropic liquid crystalline polymers in electric and magnetic fields. Review

Abstract The basic concepts of the electro- and magneto-optical behaviour of polymeric liquid crystals are examined. An analysis is made of the main experimental evidence making it possible to discern two main trends in the development of research into the influence of the external fields on liquid crystalline polymers: effects found in polymers and peculiar to low molecular weight systems and processes due to the polymer state of liquid crystals. Possible ways of making practical use of liquid crystalline polymers as media (film materials) with regulated optical characteristics are discussed.

Features of layer orderliness of cholesterol-containing polymers☆

Abstract The structure of cholesterol-containing homopolymers in the smectic and cholesteric mesophases has been studied by the X-ray method. It is shown that the polymers form a smectic mesophase of the S A -type in which the side mesogenic groups are arranged perpendicular to the planes of the smectic layers with the co-existence of two types of packing-with antiparallel disposition of the mesogenic groups and with overlap of the terminal aliphatic substituents. In the cholesteric mesophase layer order in the arrangement of the mesogenic groups exists. A scheme of packing of the macromolecules in the cholesteric mesophase is proposed.

The synthesis and structural investigation of polymers and copolymers of the cholesterol ester of methacryloyl-ω-hydroxypentadecanoic acid☆

Abstract The results of the synthesis and structural analysis and study of certain physicochemical properties of the cholesterol ester of methacryloyl-ω-hydroxypentadecanoic acid are presented, as well as those of the polymers and copolymers of the latter monomer with butyl methacrylate and butyl acrylate. The transition temperatures have been identified and the polymer and copolymer structures investigated. The fact of the formation of a liquid crystalline structure in the glass-like, high elastic and viscous flow states is proved. Boundary conditions have been found under which the liquid-crystalline state is realized for the copolymers, and a study has been made of the effect of the conditions of formation of films of the homopolymers on their ability to display optical anisotropy.

Structure formation in liquid crystalline polymers containing cholesterol

Abstract Polarization luminescence, spectropolarimetry, X-ray diffractometry, electron microscopy and optical microscopy were used to examine structure formation in polymers containing cholesterol and homopolymers of cholesteric ester of N-methacryloyl-ω-amino lauric acid and its copolymers with butylmethacrylate of different compositions. It was shown that in solutions of these polymers in non-polar solvents near the point of phase separation conformation transition is observed which is accompanied by the formation of a perfect intramolecular structure. A comparison of the structure and properties of polymer films, obtained from different solvents suggests that the formation of an intramolecular structure is a requisite condition of the liquid crystalline state in films.

Relaxational transitions and the structure of poly-N-n-octadecylacrylamide☆

Abstract The variation in dielectric relaxation, refractive index, IR absorption and thermomechanical behaviour of poly-N-n-octadecylacrylamide, is studied in the temperature range of −170° to +160°. Transitions have been detected in the region of melting of the side chains of the polymer, close to the glass temperature and in the high elastic state. A molecular interpretation of these processes is proposed.

Features of molecular mobility in solutions of comb-like polymers with mesogenic groups in their side chains

Abstract The molecular mobility of cholesteryk ether of poly(methacryol-ω-hydroxyundecanoic acid) in dilute solution was studied by the dielectric method. The polymer exhibits cooperative internal motion with unusually high correlation times, similar to those previously observed in solutions of polymers with diphenycyanide groups in their side chains. The effects of the structure of the side chain, of polymer molecular mass and of the thermodynamic quality of solvent on the parameters of the relaxation process were studied. In solutions of this type of polymers, elements of structural order are assumed to exist.

Structure of comb-like polyorganophosphazenes

Abstract X-ray analysis and small-angle scatter of polarized light have been employed to study the structure of some comb-like polyorganophosphazenes with alkyl and aryl radicals in the side chain. It is shown that in the case of alkyl substituents crystallization is observed only at quite large lengths (12 carbon atoms) while in polyorganophosphazenes with aryl substituents both the side groups and main chains are incorporated into the crystalline lattice.