I.I. Konstantinov

X-ray diffraction studies on liquid crystalline order in vinyl polymers with mesogenic side-groups

Abstract X-ray studies on some vinyl polymers with azobenzene sidegroups were performed. A model of layered structure rearrangement resulting from the substitution of the methacrylate main chain for the acrylate is proposed. It has been shown that the perfection of a layered structure is reduced with shortening of the flexible tail of the mesogenic group. Improvement of LC order with increase of temperature was revealed.

Structure of polymer blends and copolymers based on liquid crystalline compounds from phenyl benzoates

Abstract Structure analysis of liquid crystalline polymer blends and copolymers with side mesogenic groups from the phenyl benzoate series was carried out. Components of the polymer blends were shown to maintain their individual layer structure. However, upon mixing liquid crystalline ordering decreases. A new type of layer structure ensuring a denser packing of the side groups is realized in the copolymers. In isotropic melts, a weak inhomogeneity of density distribution due to the correlation hole effects is maintained.

Hydrodynamic and optical behaviour of polyester molecules of alkoxybenzoates and their dependence on molecular weight

Abstract A study of progressing diffusion, sedimentation, viscosity and flow birefringence of phenylmethacrylyl ester fractions of cetyl- (C 16 ) and nonyloxybenzoic acids (C 9 ) in tetrachloromethane indicates that the equilibrium rigidity of the main chain of C 16 ( S = 22) and C 9 ( S = 16) polyester molecules, determined from hydrodynamic results somewhat exceeds the rigidity of molecules of a similar structure but without these side groups. A reduction in birefringence for C 16 and C 9 polyesters with an increase of molecular weight was observed experimentally. This abnormal variation in the optical anisotropy of macromolecules is, apparently, the consequence of a reduction in the orientation order in macromolecular side chains.

Molecular mobility in polymers with aromatic mesogenic groups in their side chains

Abstract The dielectric relaxation parameters of two polymers of the methacrylic series having pendant mesogenic groups of the phenylbenzoate class have been investigated in the audible frequency range at temperatures below the glass transition. In studies of these polymers in the bulk state, several relaxation processes involving dipole polarization have been observed; these can be related to the mobility of various kinetic units in the pendant group. A study of the intramolecular mobility of the polymers in solution has shown that there is structural order in the positioning of the side groups.

Intramolecular liquid crystalline structure in polynonyloxybenzamide styrene solutions

Abstract Dynamo- and electro-optical properties of polynonyloxybenzamide stryrene solutions in benzene were studied. It was shown that in this polymer lateral chain groups form an intramolecular liquid crystalline structure. As a consequence, macro-molecules are characterized by the presence of an oriented polar short range order in the mutual arrangement of side radicals.

The liquid-crystalline intramolecular order and the electron-optical properties of polyalkoxy benzoate molecules☆

Abstract The dependence of the equilibrium and non-equilibrium electron-optical properties (the Kerr effect) on molecular weight have been studied on the solutions of methacrylphenyl esters of cetyl- and nonylhydroxybenzoic acids. The experimental Kerr dispersions point to the existence of fairly large intramolecular areas which become oriented by an alternating electric field. The orientation time τ for these is fairly large (about 10 −4 −10 −5 sec) and is practically independent of the molecular weight of the polymer, which is due to the relatively large mobility of these areas. The experimentally observed increase in the Kerr equilibrium constants K with the molecular weight M (in the Gaussian range of M ) is the consequence of the existence of a mesomorphic intramolecular state of the branched polyester chains.

Effect of shape of mesogenic group on the formation of liquid crystalline phase in polymers

Abstract Mesomorphic behaviour of four polymethacrylates with mesogenic side groups has been studied. In contrast to monomers which are nematogenic, mesogenic groups in the polymers form layer structures of the smectic type. A thermodynamic stable mesophase is supposed to be realized in polymers which consist of macromolecules of secondary structure, considering a macromolecule as the smallest structural element of the polymer system.

The effect of chemical constitution of mesogenic monomer unit on liquid crystalline properties of polymers

Abstract Glass transition temperatures and thermodynamic parameters of mesophase melting of polymers with mesogenic side-groups of the phenyl benzoate class depend on the length of the alkoxy substitutent, the mobility of the mesogenic groups and the nature of the main chain. Polymers with mesogenic groups connected directly to the main chain, obtained by precipitation from solution, have equilibrium liquid crystalline structures in which the macromolecules exist in a compact coil conformation with an ordered arrangement of the mesogenic groups. The nature of the main chain of these polymers affects the liquid crystalline structure. Mesophase melting parameters of the polymers with mesogenic groups, connected by flexible spacer groups to the main chain, are almost independent of the thermal history of the samples. These polymers in the isotropic melts are assumed to contain aggregates of the mesogenic groups.

Hydrodynamic and conformational properties of molecules of the poly-p-methacryloyl oxybenzoic ester of p-n-nonyloxyphenol☆

Abstract Poly- p -methacryloyl oxybenzoate of p -n-nonyloxyphenol has been synthesized for the first time. The intrinsic viscosity, translational diffusion and rapid sedimentation have been investigated for fractions with MW in the range (1·19−17) × 10 5 kg/kmole. A discrepancy was noted in Kuhn segment lengths obtained from measurements of translational friction and viscometry, using present day hydrodynamic theories of the vermicular (persistent) model. This is directly related to a discrepancy between the experimental and theoretical values of the hydrodynamic constant A 0 .

Influence of length of the aliphatic group on the character of liquid-crystalline orderliness in polymers with phenyl benzoate side groups☆

Abstract An X-ray investigation has been made of a number of polymers with side mesogenic groups and different degrees of bonding of side groups and the main chain. Models of layered packing are proposed for the members of the series studied. It was found that with increase in the length of the spacer groups by more than 1·2 nm separate packing of the chains and side mesogenic groups takes place. The corresponding polymer is crystalline at room temperature. On melting this polymer the smectic B-phase forms. Rise in temperature leads to increase in the concentration and size of the regions of liquid crystalline orderliness in polymers with strong bonding of the main chains and side groups and worsening of the orderliness in the polymer with independent packing of the main chains and side groups.