G.F. Kolbina

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.

The equilibrium and kinetic flexibility of the poly-(cetyl p-methacrylylhydroxybenzoate)☆

Diffusion, sedimentation, viscometric and flow birefringence methods in an electric field were used to investigate poly-(cetyl p-methacrylylhydroxybenzoate) (PMHC). Equations have been compiled in which the intrinsic viscosity, the diffusion coefficient and that of sedimentation were found as dependences of the molecular weight M, namely [η] = 3·3 × 10−3M0·8, D = 3·3 × 10−4M−0·6, and S0 = 8·1 × 10−15M0·4. The optical anisotropy of the segment has been experimentally determined as α1 − α2 = −440 × 10−25 cm3, that of the monomer chain unit as a‖ − a⊥ = −18 × 10−25 cm3, and the dipole moment of the segment as μ = 7·5 Debye. The PMHC molecule was found to behave in an electric field as a flexible kinetic chain, but the value of the kinetic chain segment was much superior to the size of the monomer unit, which obviously is the consequence of an orientational reaction between the branches (secondary groups).

Electrical and flow birefringence of ladder polychlorophenylsilsesquioxane solutions

A study was made of the flow birefringence (FBR) and electrical birefringence (EBR) of dilute solutions of a number of cyclolinear (ladder) polychlorophenylsilsesquioxane (CLCPS) fractions. The FBR and EBR are negative in sign, and their characteristic values increase with molecular mass in line with behaviour characteristic of polymers featuring equilibrium rigidity. The Kerr effect dispersion appearing in sinusoidal fields is characteristic of kinetically rigid chains, and its dependence on molecular mass is quantitatively in agreement with the theory of the relaxation and rotational friction of rigid molecules. The validity of a CLCPS molecular model in the form of a double chain ladder cis-structure is borne out by experimental results, and yields quantitative information concerning important molecular parameters such as the mode of rotation of side phenyl rings, the size of bond angles in the chains and oxygen bridges and the dipole moments of the monomer unit of the molecular chain and the SiO bond.

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.

Optical anisotropy and rigidity of molecules of a comb-like polymer with mesogenic side groups☆

Synthesis of a new type of comb-like polymer with mesogenic side groups — poly[(4-methacryloyloxy)benzoyl-(4-hexadecyloxy)benzoyl hydroquinone] is described. Flow birefringence [n], intrinsic viscosity [η] and molecular weight of whole polymers and fractions have been measured. The optical anisotropy α1-α2 of this polymer is −4900 × 10−31 m3 in chloroform and −3000 × 10−31 m3 in benzene. The equilibrium rigidity has been estimated on the basis of measured hydrodynamic characteristics: Kuhn segment in chloroform is A=(140±8) A. It has been shown that a high degree of intramolecular axial orientational order is characteristic for this polymer, brough about by interactions between the long side chains containing mesogenic groups.

Hydrodynamic properties and equilibrium rigidity of oxypropyl cellulose molecules

The hydrodynamic properties—characterisctic viscosities [ν], translational diffusion D and sedimentation S0— of samples and fractions of oxypropyl cellulose have been investigated in a number of solvents. The relations linking the magnitudes [ν], D and S0 with the degree of polymerization have been established. From the data on translational diffusion and viscometry the authors have determined the equilibrium rigidity of the macromolecules: the size of the statistical segment is (210–240) × 10−8cm. The high rigidity of the macromolecules determines the possibility of the formation of the mesophase in solutions and melts of oxypropyl cellulose.

Conformation and optical anisotropy of comb-like macromolecules with mesogenic side groups☆

Abstract The methods of flow birefringence and viscometry have been used to make a comparative study of the conformational properties of two comb-like polymers differing in the character of attachment of the mesogenic grouping. It is shown experimentally that the distancing of the mesogenic grouping from the main chain is accompanied by sharp fall in the optical anisotropy of the molecule and the intramolecular orientation order as compared with the anisotropy and degree of orderliness of the polymer molecules in which the mesogenic group is attached directly to the main chain.

Conformation properties of copolymers of cetyl methacrylate with butyl and octyl methacrylate

Abstract Conformation properties of copolymers of cetyl methacrylate and butyl and octyl methacrylate were studied by viscometry, sedimentation and.diffusion analysis and dynamic birefringence. Ratios were derived, which relate intrinsic viscosity [η], the diffusion coefficient D , constant of sedimentation S 0 for all polymers examined. From the evaluation of unperturbed dimensions it was concluded that average random copolymers of cetyl methacrylate with butyl and octyl methacrylates have rigidities, very similar to those of the polycetylmethacrylate chain, i.e. “dilution” of units of the latter by octyl and butyl methacrylate units has no effect on main chain rigidity, whereas the segmental optical anisotropy of copolymers is much lower than for polymethylmethacrylate.

Optical and hydrodynamic properties of a comb-shaped mesogenic polymer and its copolymer☆

The hydrodynamic (translational diffusion, sedimentation, and intrinsic viscosity) and optical (flow birefringence) properties of a comb-like mesogenic homopolymer and its copolymer are studied. Equations are obtained connecting the diffusion and viscosity with the MM. The equilibrium rigidity of the homopolymer and copolymer in different solvents is determined: the value of the Kuhn segment of the whole polymer is A=45 A in tetrachloromethane and A=55 A in dioxane as against A=40 A in tetrachloromethane and A=58 A in benzene for the copolymer respectively. The optical anisotropy of the copolymer molecule reflects the high (intra-molecular) orientational order and the fact that it is essentially dependent on the concentration of the mesogenic groups and their location relative to the molecule backbone.

Intrinsic viscosity and flow birefringence of some comb-like polymers having mesogenic side groups as a function of temperature☆

Abstract The intrinsic viscosity [η] and the flow birefringence of two comb-like polymers as a function of temperature are studied in various solvents. In solvents in which the macromolecule dimensions are smaller the change in [η] is indicated by the positive temperature coefficient and vice versa. The change in macromolecule dimensions with temperature is reflected in the change in flow birefringence.