Anisotropic thermosets from liquid‐crystalline azomethynic epoxy resins and primary aromatic diamines

Novel epoxy‐terminated monomers based on imine groups were synthesized and their mesogenic properties studied. Aliphatic spacers of different lengths were introduced between the rigid unit and the glycidylic group, and their liquid‐crystalline behavior was examined. They were reacted with primary aromatic diamines inside a magnetic field so that the formation of anisotropic networks could be investigated. The influence of curing conditions and the structure of monomers and amines on the formation of liquid‐crystal thermosets were investigated. Thermosets with locked nematic textures were obtained in all cases. The influence of a 7.1 T magnetic field on the macroscopic orientation of these materials was studied, and mechanical properties of the resulting networks were evaluated by dynamic mechanical analysis. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1–12, 2003     

Models of polarized states of the physical vacuum and torsion fields

A model is proposed of the physical vacuum, taking into account the existence of fields generated by classical spins or angular momenta of rotation.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 13–23, March, 1992.     

Charge-transfer complexes betweenp-toluidine and iodine in solution: A spectrophotometric and voltammetric study

The charge-transfer interaction between an aromatic amine (p-toluidine) and a halogen (iodine) is investigated in different solvents. The effects of the solvent dielectric constant, of the ionic strength and of the light absorbed on the transformation of the intermediate “outer” complex into a polar “inner” structure are studied. An overall reaction mechanism is suggested.     

NMR of57Fe in erbium-yttrium iron garnets

NMR of 57Fe was studied by the two pulse spin echo method in systems Er(x)Y(3−x)Fe5012. For small (x<0.3) or large (x>2.7) concentrations of Er the spectra of 57Fe exhibit resolved satellite lines. The splitting between the satellite and the parent line reflects the change of the dipolar field on the Fe nuclei (diamagnetic yttrium is replaced by magnetic erbium ion) and the change which the substitution causes in the electronic structure of the ferric ion. Relative importance of these effects is discussed.     

Expanding the scope of solvent-free synthesis: entrapment of thermally unstable species

The use of the acetone monoadduct, [Rh₂(O₂CCF₃)₄·(OCMe₂)], instead of unligated dirhodium(II) tetrakis(trifluoroacetate) in sublimation-deposition reactions allowed us to study coordination of thermally sensitive 1,4-diiodo-1,3-butadiyne. A new mixed-ligand organometallic compound, [Rh₂(O₂CCF₃)₄·(OCMe₂)]₂·(C₄I₂), has been isolated in crystalline form and shown by X-ray diffraction study to have an η²(1,2):η²(3,4)-bridging mode of diyne. This has demonstrated the donor ability of the diiodobutadiyne that was previously known to act as a π-acceptor through the Lewis acidic iodine atoms. This work has expanded the temperature limits of the solvent-free synthesis strategy for potential study of thermally unstable species.     

Formation of a volume discharge at a subnanosecond rise time of the voltage pulse

A study is made of the formation of a volume discharge in atmospheric-pressure air in a nonuniform electric field without additional preionization. It is shown that the spatial distribution of the plasma glow between a plane and a spherical (as well as a point) electrode at a subnanosecond rise time of the high-voltage pulse is volumetric in character. The change of the voltage polarity does not qualitatively affect the character of the glow. The propagation of a spherical ionization wave in nitrogen is calculated in the drift-diffusion approximation. The fact that the character of the discharge glow is essentially independent of the voltage polarity is explained by the multiplication of the background electrons in the dense working gas.