O. F. Pozdnyakov

Trapping of solvent by a C60 fullerene film

Mass spectrometry was used over a wide temperature range to compare processes of solvent (toluene) release and desorption of C60 fullerene molecules from a fullerite film formed from solution on an oxidized metal substrate. It is shown that toluene is strongly retained in the fullerite film and that it is almost impossible to remove the toluene from the film without damaging its structure. Quantitative characteristics of the toluene retention and trapping effect are determined.

Influence of the deformation type and medium on the mechanodynamic penetration of nitrogen molecules into surface layers of armco iron

The extraction of nitrogen molecules from deformed samples of armco iron with different initial structures (annealed and subjected to equal-channel angular pressing) and different deformation prehistories (deformation in liquid nitrogen at 77 K, rolling in air at room temperature, and their combination) has been studied. It has been shown that the preliminary deformation in liquid nitrogen increases its concentration in the surface layer of the material and shifts the principal peak of its release toward low temperatures during heating. The results are associated with the existence of different types of nitrogen traps in annealed and nanostructured armco iron and with their changes during subsequent deformation.

Mechanism for thermal destruction of polystyrene grafted to fullerene C60

A model is proposed for the thermal destruction of polystyrene covalently bonded to C60 and this is used to explain various characteristics of its experimental mass thermograms.

Determining conditions for the preparation of polymer films containing an ordered structure of carbon nanotubes and higher fullerenes

The experimental conditions necessary for the preparation of polymeric composite films (membranes) containing an ordered structure of single-wall carbon nanotubes and higher fullerenes are determined. The films are obtained by ordering a homogeneous suspension of carbon nanotubes and fullerenes in the initial liquid prepolymer or monomer, followed by curing of the matrix. The parameters of ordering (duration, field strength) are estimated, which make possible realization of the proposed process for the preparation of carbon-containing composite films based on polymer matrices of the polycyanurate type.

Mass spectrometry of carbon nitride C3N4

Carbon nitride has been synthesized in macroscopic amounts by means of the original method based on an ecologically safe technology using inorganic initial compounds. The product has been characterized by mass spectrometry (MS), X-ray diffraction, and quantitative chemical analysis. The MS and thermochemical data show that stoichiometry of the samples of carbon nitride obtained using the proposed method corresponds to the empirical formula C3N4.

Fullerene C60 diffusion in thin layers of amorphous polymers: Polystyrene and poly(α-methylstyrene)

The outdiffusion of fullerene C60 from submicron films of polymer-fullerene blends has been studied by thermodesorption mass spectrometry (TDMS). The energy parameters of C60 diffusion in polystyrene and poly(α-methylstyrene) were determined and compared to the parameters of desorption of C60 molecules from a multilayer film of pure fullerene deposited onto a substrate from toluene solution.

UV photostability of PMMA-C60 fullerene composition

Thermal decomposition of pure poly(methyl methacrylate) (PMMA) and its composition with C60 fullerene before and after UV irradiation has been studied by thermodesorption mass spectrometry (TDMS). It is established that low-temperature depolymerization of UV-irradiated PMMA is suppressed in its composition with C60. Possible molecular stabilization mechanisms are discussed.

Investigation of the concentration gradient and extraction of helium atoms from copper deformed in a liquid-helium medium

A complex investigation of the penetration, accumulation, and extraction of helium atoms in porous copper samples deformed in a liquid-helium medium has been performed. The experiments have been carried out using three mass spectrometric techniques: (1) ionization of helium atoms by an electron impact in an MSCh-6 mass spectrometer, (2) secondary ion mass spectroscopy, and (3) an original high-resolution method with a sensitivity threshold of ∼1094He atoms. The results obtained have made it possible to determine important characteristics of mechanodynamic diffusion of helium atoms, such as their penetration depth, the true concentration of helium trapped under deformation, and its gradient with an increase in the distance from the surface, as well as to estimate the binding energy of helium in traps.

Studying polymer-on-metal friction by thermodesorption mass spectrometry

A method for determining the parameters of thermal decomposition of polymer layers transferred onto a metal counterbody surface in the course of friction has been developed on the basis of thermodesorption mass spectrometry (TDMS). The efficacy of the proposed method is demonstrated using experimental data for poly(tetrafluoroethylene), polystyrene, and poly(methyl methacrylate) (PMMA). Using TDMS, it is possible to distinguish between damaged and intact molecules transferred in the course of friction in a relatively soft regime. TDMS data revealed differences in the character of thermal decomposition in the layers transferred during the friction of pure PMMA and PMMA-fullerene (C60) composition on steel.

Thermal desorption states of C60 fullerene molecules in polymer matrices

Polymer-C60 fullerene composite coatings are studied using thermal desorption mass spectrometry. It is found that thermal desorption spectra of C60 fullerene molecules can exhibit several resolved peaks (at a specified heating rate) corresponding to thermal desorption states. The relative intensity of the thermal desorption peaks depends on the procedure used for preparing the composite coatings, in particular, on the time of sedimentation of the polymer-fullerene suspension. The occurrence of different stages in thermally stimulated desorption of C60 fullerene molecules is explained by the fact that the fullerene molecules can exist in several phase states characterized by different densities and degrees of ordering in the polymer matrix.