P. N. Lavrenko

Hydrodynamic and electrooptical properties of star-shaped heteroarm fullerene (C60)-containing polymers in solutions

Star-shaped heteroarm polymers with a C60 branching center and polystyrene and poly(2-vinylpyridine) arms of equal molecular masses have been studied by the methods of molecular hydrodynamics (translational diffusion and viscometry) and electrooptics (the Kerr effect). The experimental hydrodynamic data are interpreted in terms of the regular star model. The molecular masses and hydrodynamic sizes of star-shaped heteroarm polymers in solutions are estimated. A comparison of these values with the corresponding parameters of linear polymer-analogs (polystyrene and poly(2-vinylpyridine)) makes it possible to characterize the branching degree of macromolecules. The study of the electrooptical properties of the heteroarm polymer in benzene demonstrates the tendency of macromolecules toward aggregation.

Hydrolytic degradation and thermal stability of poly(naphthylimides) based on naphthalene-1,4,5,8-tetracarboxylic dianhydride and bis(naphthalic anhydrides)

The molecular properties of a number of new poly(naphthylimides) derived from naphthalene-1,4,5,8-tetracarboxylic dianhydride and bis(naphthalic anhydrides) have been studied. On the basis of hydrodynamic studies of the polymers at various stages of their thermal degradation in 96% H2SO4 and thermogravimetric measurements, the hydrolytic stability and thermooxidative resistance of the polymers have been compared. A correlation between the experimental data and the chemical structure of molecular chains has been established.

Hydrolytic degradation and thermooxidative stability of polyimides based on 3,5-diaminodiphenyl oxide and 2-methyl-3,5-diaminodiphenyl sulfide

For a number of new polyimides prepared from 3,5-diaminodiphenyl oxide, 2-methyl-3,5-diaminodiphenyl sulfide, and various dianhydrides of aromatic tetracarboxylic acids, the hydrolytic stability in DMF and 96% H2SO4 and the thermooxidative stability in the bulk have been studied. Hydrodynamic techniques have been employed to determine the molecular parameters of these polymers at various stages of degradation. It has been shown that the polymers under study form stable solutions in DMF but turn out to be unstable in 96% H2SO4 even at room temperature. Degradation accompanies dissolution of the polymer. The correlation between the chemical structure of polymer molecules and their hydrolytic stability in both solvents has been established. It has been demonstrated that the majority of the said polyimides are stable in the solid state at temperatures up to 400°C and marked degradation begins only above 500°C.

Hydrodynamic, electrooptical, and conformational properties of fullerene-containing poly(2-vinylpyridines) in solutions

For C60 fullerene-containing poly(2-vinylpyridines) synthesized by anionic polymerization, the molecular mass and hydrodynamic size of macromolecules in solutions have been determined by molecular hydrodynamics (translational diffusion and viscometry) and electrooptics in dilute benzene and THF solutions. Under the same conditions in the molecular mass range (9.8–123) × 103, the hydrodynamic behavior of linear poly(2-vinylpyridines) and their molecular-mass dependences have been examined and the conformational characteristics of macromolecules have been established. The branching of macromolecules has been characterized by comparing the properties of star-shaped fullerene-containing and linear poly(2-vinylpyridines). With consideration of the hydrodynamic data interpreted within the framework of regular star model, it is inferred that on average three to four linear polymer chains with a molecular mass of (8 ± 3) × 103 for each chain are attached to a fullerene core of C60 in molecules of fullerene-containing poly(2-vinylpyridines). The specific Kerr constant of fullerene-containing poly(2-vinylpyridines) in dilute benzene solution is −(14 ± 1) × 10−12 cm5/[g (300 V)2]. As evidenced by the electrooptical data, the incorporation of fullerene into the polymer weakens self-association of macromolecules in solution.

Dynamooptical and electrooptical properties of poly(methylphenylsiloxane) in solution and bulk

The dynamooptical, electrooptical, and hydrodynamic properties of a low-molecular-mass poly(methylphenylsiloxane) containing 33% phenyl radicals (with respect to the total amount of side groups) in dilute solutions and in bulk are studied. The size of macromolecules, as well as the molecular mass of the polymer, its shear optical coefficients Δn/Δτ = (0.29 ± 0.3) × 10−10 (in decalin) and (0.43 ± 0.03) × 10−10 cm s2/g (in bulk), and the specific Kerr constants K = (2.30 ± 0.02) × 10−12 (in benzene), (2.23 ± 0.02) × 10−12 (in decalin), and (2.24 ± 0.09) × 10−12 cm5/[g (300 V)2] (in bulk), are estimated and compared with the corresponding characteristics of poly(dimethylsiloxane). The effect of solvents on the intramolecular mobility, optical anisotropy, and dipole structure of polymer macromolecules is considered.

Synthesis of fullerene-containing polymer composites and investigation of interactions in these systems

The methods of synthesizing fullerene-containing polymer composites are analyzed. It is established that the technique of determining the intrinsic viscosity can be used for evaluating the effect of the fullerene involved in the polymer composite on the polymer chains. The influence of the synthesis procedure on the fullerene content in a water-soluble fraction is demonstrated using the poly(N-vinylpyrrolidone)-C60 (PVP-C60) system as an example.

Molecular properties of C60 fullerene complexes with cycle-containing polymers in solutions

The donor-acceptor complexes of the C60 fullerene with cycle-containing polymers, namely, poly(2,6-dimethyl-1,4-phenylene oxide) (PPhO) and poly(N-vinylpyrrolidone) (PVP), are studied. A comparative analysis of the hydrodynamic and electrooptical properties of the initial polymers and their complexes with C60 in solutions demonstrates that the C60 fullerene has a restructuring effect on the polymer macromolecule, thus decreasing the degree of asymmetry of the macromolecular structure.