L.L. Burshtein

Investigation of gelation in poly(hexadecyl acrylate) solutions

Abstract A study was made of characteristic effects of thermally reversible gelation on the dielectric properties, electrical conductivity, proton magnetic relaxation properties and self diffusion in the system polydecadecyl acrylate-n-decane with differing ratios of the components. It is shown that the effects in question are attributable to changes in the mobility of the kinetic units of the macromolecules, ion impurities, and in the rotational and translational mobility of solvent molecules during macromolecular network formation.

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.

Molecular motion and mesophase transitions occurring in comb-like cholesterol-containing polymers*

A study has been made of temperature-frequency dependences of tan δ for polymers of cholesteryl esters of N-methacryloyl-ω-amino- and ω-hydroxycarboxylic acids containing mesogenic cholesteryl groups at the end of a side pendant. The dynamic behaviour of macro-molecules of these polymers is shown to be largely dependent on the polar group (amide or ester) located in the base of the side chain and creating conditions that are conducive, or otherwise, to realization of the liquid crystalline state. Possible uses of a dielectric means of detecting polymorphic structural transitions in mesophase and on transition to the isotropic state are highlighted.

Dielectric relaxation in poly-N-n-octadecylmethacrylamide

Dielectric relaxation in the comb-like polymer poly-N-n-octadecylmethacrylamide has been investigated and the results obtained have been compared with data from poly-N-n-octadecylacrylamide with the aim of studying the effect of the nature of the α-substituent, the number of hydrogen bonds and the conformational structure on intramolecular motion. It has been shown that the relaxation time and the activation energy in the region of the dipole relaxation connected with the local mobility of the amide group are not dependent on the factors mentioned and are determined by the interaction between side chains. It is characteristic of both polymers that there is no clearly expressed dielectric α-transition in the region of the glass transition but an intense relaxation process is observed in the rubbery state of the polymers. Its cause is attributed to the specific effect of hydrogen bonds.

Intramolecular mobility of polymers with mesogenic groups in the side chains

Abstract The molecular mobility in dilute solutions of esters of poly-ω-methacryloyloxycarboxylic acids has been investigated. Two relaxation processes involving dipole polarization have been observed in these systems. It has been shown that the process connected with the mobility of end polar groups may be used in analysing the intramolecular structure-formation. The effect of the length of the aliphatic “spacer” and the structure of the end group in the side chain on the intramolecular mobility of the macromolecules has been elucidated.

Intramolecular ordering of copolymers containing cholesterol

Abstract A study was made of dielectric polarization in dilute copolymer solutions of cholesterol ester of N-methacryloyl-ω-aminolauric acid with n-butylmethacrylate and n-decylmethacrylate and homopolymers. It was shown that conformation properties and intramolecular ordering in copolymers containing cholesterol are determined not only by the concentration of mesogenic groups in the macromolecule, but also by specific features of dispersion interactions of alkyl radicals of aliphatic comonomers.

The dielectrical relaxation and liquid-crystalline state in copolymers of 1-methacryloyl-oxybenzoyl-phenylene-4-anisoate with styrene☆

Abstract The relaxational and mesophase phenomena in random copolymers of styrene with 1-methacryloyl-oxybenzoyl-phenylene-4-anisoate having the mesogenic group in the side chain, have been studied. The limits of existence of the LC phase in relation to the quantity of mesogenic component have been determined. The presence of mesophase transitions in the LC composition region was found. A multiplicity of forms of internal motion was demonstrated in the side chains of the mesogenic component.

Dielectric transitions in comb-like polyacrylate derivatives having azomethine mesogenic groups in their side chains

The dielectric behaviour of comb-like liquid crystalline acrylic polymers with azomethine mesogenic side chain groups have been studied over a wide temperature range. The relaxational and phase transitions, related to the mobility of definite kinetic units has been observed and the corresponding relaxation times and activation energies of dipole polarization evaluated.

Liquid crystalline polymers with amino acidic fragments in side chains

Monomers and polymer of Nα-acyl derivatives of Ne-methacryloyl-L-lysine differing as to the length of alkyl radicals have been synthesized and physicochemically investigated. Structural investigations have been carried out for the monomers and polymers, and the influence of the diphilic structure of macromolecules on the formation of optically anisotropic structures has been elucidated over a wide range of temperature.