N. A. Shmakova

Direct-Current Discharge Treatment of Polytetrafluoroethylene Films

The effect of treatment in a low-pressure dc discharge on the surface properties of polytetrafluoroethylene (PTFE) films modified at the anode and cathode was examined. It was found that the anode treatment of the films considerably improves the adhesive properties of the polymer and makes it possible to obtain substantially lower values of the contact angle and higher values of the work of adhesion and surface energy than in the case of other PTFE surface modification techniques. By means of IR and X-ray photoelectron spectroscopy, it was shown that discharge treatment at the anode and cathode noticeably increases the amount of oxygen-containing groups on the surface of the films.

Formation of metal-polymer hybrid nanostructures during radiation-induced reduction of metal ions in poly(acrylic acid)-poly(ethylenimine) complexes

The formation of nanoparticles during the radiation-induced chemical reduction of silver ions, copper ions, and nickel ions in films based on poly(acrylic acid)-poly(ethylenimine) complexes are studied via electron microscopy. This approach allows preparation of composites containing nanoparticles that are randomly distributed in the polymer matrix and materials with a regular spatial distribution of nanoparticles across the film thickness and in subsurface layers. The structure of metal-polymer hybrid materials is dependent on the irradiation conditions, the type of reduced metal ions, and their initial content in polymer matrices. The ratio between the rate of nucleation and the rate of growth of nanoparticles in the matrices of interpolyelectrolyte complexes depends on the intensity of the absorbed dose and on the mechanisms of reduction of metal ions and formation of clusters. The IR spectroscopic studies reveal the effect of nanoparticles on the chemical structure of the polymer matrix.

Modification of the Surface Layers of Fluoropolymer Films by DC Discharge for the Purpose of the Improvement of Adhesion Properties

The effect of dc discharge treatment at the anode and cathode on the surface properties of polytetrafluoroethylene (PTFE), tetrafluoroethylene–hexafluoropropylene copolymer (FEP) and poly(vinylidene fluoride) (PVDF) polymer films was studied. It was found that the modification of the films under conditions that ensure the separation of the discharge active species acting on the polymer materials makes it possible to achieve substantially lover values for the contact angle and higher values for the surface energy than in the case of other modes of discharge. The changes in the composition and structure of the films were studied by means of IR spectroscopy and electron spectroscopy for chemical analysis (ESCA). It was found that new oxygen-containing groups are formed on the polymer surface as a result of dc discharge treatment. To appreciate the adhesion characteristics of fluoropolymer films modified by dc discharge, American Society for Testing and Materials Standard Test Method for Measuring Adhesion by Tape Test (ASTM D3359-02) was used. The adhesion tape Scotch 810 and vacuum metallization of the film surface are account for the basis of this method. It was found that the adhesive bonding strength of the plasma treated films substantially increased.

Surface modification of vinylidene fluoride-hexafluoropropylene copolymer films by direct-current discharge treatment

Changes in the contact properties of the surface of a vinylidene fluoride-hexafluoropropylene copolymer film by dc discharge treatment were studied. It was found that the modification considerably improved the contact properties of the films because of the appearance of oxygen-containing polar groups on the polymer surface. The formation of these groups was detected by X-ray photoelectron spectroscopy and Fourier-transform IR spectroscopy.

Modification of Tetrafluoroethylene-Hexafluoropropylene Copolymer Films in Direct-Current Discharge

The effect of dc discharge treatment at the anode and cathode on the surface properties of tetrafluoroethylene-hexafluoropropylene copolymer films was studied. It was found that the modification of the films under conditions that ensure the separation of the discharge active species acting on the polymer materials makes it possible to achieve substantially lower values for the contact angle and higher values for the work of adhesion and surface energy than in the case of other modes of discharge. A change in the composition and structure of the films was studied by means of IR and X-ray photoelectron spectroscopy. It was found that new oxygen-containing groups are formed on the polymer surface as a result of plasma discharge treatment.

IR Spectroscopic Study of Chemical Transformations upon Irradiation of the Poly(vinyl chloride)–Triallyl Cyanurate System

Chemical transformations resulting from irradiation of the poly(vinyl chloride) (PVC)–triallyl cyanurate (TAC) system were studied by IR spectroscopy. It was shown that crosslinking was accompanied by scission of the network structure formed in the initial dose range, and the scission process occurred even at small irradiation doses. The scission is assumed to be localized at the interface boundary between PVC and poly(iso-TAC) or poly(TAC).

Modification of tetrafluoroethylene-perfluoropropylvinyl ether copolymer films in direct-current discharge

Changes induced in the surface properties of films of a tetrafluoroethylene copolymer with perfluoropropylvinyl ether by direct-current discharge have been investigated, depending on the discharge parameters. It has been shown that the treatment of the films at the anode is more effective than at the cathode. A change in the contact properties of the modified films during their storage in air under ambient conditions and upon heating to 150°C has been examined. The chemical composition of the surface of the films after modification, storage, and heating has been studied by X-ray photoelectron spectroscopy and Fouriertransform IR spectroscopy. It has been found that dc discharge treatment significantly improves the adhesion properties of the films and barely affects their light transmission.

Polymer synthesis from 1-aminonaphthalene in direct-current discharge

Thin 1-aminonaphthalene polymer films have been obtained for the first time by polymerization at the cathode and anode in dc discharge. The elemental composition, chemical structure, and thermal stability of the polymer have been studied by pyrolysis chromatography, IR and UV spectroscopy, and thermogravimetry, respectively. The surface contact properties of the films and their thickness have been determined with a microinterferometer.

Change in the surface properties of poly(vinylidene fluoride) films by treatment in direct-current discharge

It has been found that treatment in dc discharge results in a substantial and time-invariant increase in the surface energy of poly(vinylidene fluoride) films. This effect is obviously due to the formation of oxygen-containing groups on the polymer surface, a fact that is corroborated by Fourier-transform IR spectroscopy and X-ray photoelectron spectroscopy data. It has been shown that dc discharge is more effective in altering the contact properties of the polymer surface than low-frequency glow discharge.

Radiation Chemistry of Organic Molecules in Solid Rare Gas Matrices: 2. Selective Deprotonation of the Primary Radical Cations upon Irradiation of Oxygen-Containing Molecules in Xenon Matrices

The composition of radical products trapped after irradiation of various ethers (dimethyl ether, tetrahydrofuran, methylal, 1,3-dioxolane) or acetaldehyde in xenon matrices at 15–17 K in the presence of electron scavengers was studied by an ESR technique. It was shown that the primary radical cations give corresponding deprotonation products (carbon-centered radicals), rather than stabilize in xenon, under the given experimental conditions. The deprotonation process is characterized by extremely high selectivity; i.e., the only type of radicals resulting from deprotonation at maximum spin density position was observed in each of the cases. The possible mechanism of the reactions and the nature of their selectivity are discussed.