T.P. Stepanova

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.

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 effect of molecular weight on the mobility and interaction of polymer molecules in solution

Abstract A study has been made of dipole polarization and of dipole moments in solutions of poly(methyl methacrylate) fractions in the thermodynamically poor solvent isopropylbenzene. It is shown that the relaxation time of the small scale process and the dipole moment are dependent on molecular weight.

Investigation of the dielectric polarization of gels of certain comb-like polymers

Abstract The dielectric polarization and dipole moments of gels formed by comb-like polymers have been investigated. It is shown that the macroscopic formation of a gel is proceeded by a conformational transition at the intramolecular level in the solution, which depends on the structure of the solvent and the polymer. It is shown that the degree of defectiveness of the supermolecular structure of the gel is also determined by the chemical nature of the polymer and the solvent.

Molecular mobility in solutions of comb-like polymers with polysiloxane backbone☆

Molecular mobility in dilute toluene and benzene solutions of comb-like polymers having a polysiloxane backbone and phenyl benzoate groups at the end of alkoxide side chains of different length (n = 1 or 6) was studied by relaxation of dipole polarization. Both polymers were found to exhibit three processes of dipole polarization relaxation, two of them local (with relaxation timesτ ∼= 10−7 sec), related to mobility of the whole mesogenic group or of its part. The third process with the longest relaxation time (τ ⋟ 10−5sec) reflects a cooperative reorientation of macromolecular segments.

Influence of the chemical structure of side chains of comb-like polymers on the gel point

Abstract A study has been made of the gel points of comb like polymers relative to the chemical structures of their side chains, using a dielectric method to determine gel points. It was found that any modification of the structure of site chains leading to intensification of intermolecular interaction increases the gelation propensity of the comb like polymers, and is reflected in a rise in the solution-gel transition temperature.

Effect of the hydrogen bond on the intramolecular organization of polymers containing cholesterol

Abstract Comparative study was made of parameters of molecular mobility of two series of “comb-like” polymers; cholesteryl esters of poly-N-methacrylyl-ω-aminocarboxylic acids and of poly-ω-methacrylyloxycarboxylic acids. It was established that the hydrogen bond affects the molecular mobility of the polar group directly linked with a cholesteryl radical. A difference was established in molecular structure in polymers of cholesteryl esters of poly-N-methacrylyl-ω-aminocarboxylic acids in dilute and concentration solutions, which is due to levelling the role of the hydrocarbon side chains by the formation of hydrogen bonds at the ester end groups on increasing solution concentration.

Study of dipole polarization in polymer solutions under critical and pre-critical conditions☆

Dipole polarization of poly-β-naphthyl methacrylate was studied under critical and pre-critical conditions. It was shown that when T = Tcr the molecular mobility of lateral polar groups and intramolecular interaction change.

The conformational state of a comb-like liquid crystalline polymer with cyanodiphenyl side groups☆

Abstract The dipole moments of of poly-ω-2-methylpropionyloxyundecyl cyanodiphenyl ester have been studied. The macromolecules of polymer have been shown to have a random coil conformation with antiparallel disposition of the cyanodiphenyl groups. The introduction of the cyanodiphenyl groups into the side chains results in an increase in molecular interaction.