Polymer films prepared from hexafluorobenzene in direct-current discharge

Polymer films with hydrophobic surface properties were prepared from hexafluorobenzene in a direct-current discharge. The films possess good dielectric characteristics (dielectric loss tangent and permittivity) in the temperature range 20–240°C. The composition and structure of this polymer were studied by means of IR spectroscopy and electron spectroscopy for chemical analysis with reference to mass-spectrometric data for the discharge gas phase.     

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.     

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.     

Modification of polypropylene films in a direct-current discharge

The surface properties of polypropylene (PP) films modified in a direct-current discharge at the anode and cathode, as well as their change during long-term storage were studied. It was shown that the greatest decrease in the contact angles and the increase in the total surface energy and the polar component are observed for the films treated at the anode. Changes in the chemical structure of PP films were investigated by means of Fourier-transform IR spectroscopy and X-ray photoelectron spectroscopy techniques.     

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.     

The adhesive properties of polyfluoroolefin films modified by direct-current discharge

The influence of the treatment of various structures polyfluoroolefine films by the direct-current discharge at the anode and cathode on the properties of the surface (the value of the contact angles of wettability, work of adhesion, and surface energy and its polar and dispersive components) is studied. Measurements of the peel strength of plasma-treated films are conducted. It is shown that the direct-current discharge treatment makes it possible to substantially increase the peel strength of the polyfluoroolefin films.     

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.     

Alteration in the surface structure and properties of norbornene-ethylene copolymer films by direct-current discharge treatment

The effect of dc discharge on norbornene-ethylene copolymer films containing 30 and 60% norbornene was studied. It was found that plasma treatment leads to substantial changes in the surface properties of the copolymer, the enhancement of wettability, and an increase in the work of adhesion and surface energy, including its polar term. The change in the surface structure of the films was investigated by means of Fourier-transform IR spectroscopy. Transparent and colorless triplexes with a light transmission of 86–90% were prepared on the basis of the discharge-modified copolymer films and a cycloaliphatic epoxy resin.     

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.     

Polymer matrix of polyethylene porous films functionalized by electrical discharge plasma

The polyethylene porous films were treated by dielectric surface barrier discharge (DSBD) plasma at atmospheric pressure in oxygen (O₂) or nitrogen (N₂), and by radio-frequency discharge (RFD) plasma in air at reduced pressure 46 Pa. The surface energy of films was carried out by direct measurements of contact angles of six testing liquids. The strength of adhesive joints in the system modified polyethylene porous films - polyacrylate was measured by peeling of the joints under the angle of 90°. The significant increase of the surface energy and its polar component of polyethylene porous films modified by all types of plasma were observed. The higher strengths of adhesive joints were found for modification of polyethylene porous films by radio-frequency discharge plasma in comparison with modification of the films by barrier discharge plasma.     

Polymerization of 1,2,4,5-tetramethylbenzene (durene) in direct-current discharge

Polymer films possessing dielectric properties were prepared from 1,2,4,5-tetramethylbenzene (durene) at the cathode in a dc discharge. The chemical structure of the films was studied by IR and UV spectroscopy. It was shown that the polymer synthesized from durene in a dc discharge contains basically polyene structures produced via the opening of aromatic rings.     

Mechanism of hydrogen peroxide formation in electrolytic-cathode atmospheric-pressure direct-current discharge

The kinetics of buildup of hydrogen peroxide in an atmospheric pressure direct-current discharge with a distilled-water cathode has been experimentally measured. A kinetic reaction scheme has been proposed and analyzed to calculate peroxide concentrations in accordance with experimental data.     

PEC films prepared from Chitosan-Alginate coacervates

Chitosan-alginate polyelectrolyte complex (PEC) have been prepared in situ in beads and microspheres. This study examines the preparation of suitable chitosan-alginate coacervates for casting into homogeneous PEC films for potential applications in packaging, controlled release systems and wound dressings. Coacervation between chitosan and alginate was rapid, but the rate may be controlled with the addition of water miscible organic solvents. Compared with ethanol and PEG200, acetone was the more promising solvent moderator. Suspensions of fine, uniformly dispersed coacervates were produced by a dropwise addition of 0.25% w/v chitosan solution (solvent: 1: 1 v/v of 2% acetic acid and acetone) into 0.25% w/v sodium alginate solution in water under rapid agitation. The PEC films were transparent and flexible. They exhibited high permeability to water vapor, but resisted complete dissolution in 0.1 M HCI, distilled water and pH 7.4 phosphate buffer solution. Microscopic heterogeneity in the films could be reduced by immersion in aqueous media, but this was accompanied by modifications in the thickness, permeability and mechanical property of the films.     

Effect of direct-current discharge treatment on the surface properties of chitosan-poly(L,L-lactide)-gelatin composite films

The surface of films made from a chitosan-poly(L,L-lactide)-gelatin mixture stabilized with a grafted-copolymer fraction has been modified by dc discharge treatment, as well as that of films made of the individual components. The surface properties of the films (wettability, surface energy), the chemical structure of surface layers, and their morphology have been examined by goniometric measurement of contact angles, X-ray photoelectron spectroscopy, and scanning electron microscopy.     

Mechanism of phenol degradation processes induced by direct-current atmospheric-pressure discharge in air

The phenol degradation kinetics and the buildup kinetics of the products hydroxyphenols, nitrophenols, carboxylic acids, and formaldehyde in electrolytic-cathode direct-current discharge have been studied, as well as the formation of nitric acid. On the basis of the results, a scheme of the processes has been proposed; calculations according to this scheme describe well the experimental data on the degradation kinetics of phenol and the formation/decay kinetics of its transformation products.     

Au nanoparticle micropatterns prepared from self-assembled films

A kind of hybrid multilayer film based on mercaptobenzoic acid-capped Au nanoparticles (MBA-Au-NPs) and photoreactive nitrodiazoresin (NDR) has been fabricated via electrostatic self-assembly. Upon exposure to UV light, the initial ionic bonds between the layers of the film convert into covalent bonds and the film stability toward polar solvents, salt, or surfactant solutions increases significantly. The micropatterned NDR/MBA-Au-NP film with the covalently linked architecture was formed by selecting exposure of the film through a photomask and later developed in sodium dodecyl sulfate (SDS) aqueous solution. The metallic Au-NP micropatterns, furthermore, are produced by sintering the micropatterned NDR/MBA-Au-NP film at 550 degrees C, at which the organic components are removed completely. The well-defined micropatterns were characterized with atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM), microscope with a charge-coupled device (CCD) camera, and X-ray photoelectron spectroscopy (XPS).     

Colored thin films prepared from hydrogel microspheres

Ordered 2-D structures composed of poly(N-isopropylacrylamide) (PNIPAM) microgel particles that had regularity on a sub-micrometer length scale were prepared. By using sterically stabilized PNIPAM microgel particles as components, the ordered array was formed by a self-assembly process. The particle array was prepared by depositing a droplet of the microgel dispersion on a substrate. Atomic force microscopy observation of the resulting thin films revealed that they comprised a monolayer particle array. The periodic structure of the array produced iridescent colors due to optical diffraction. Since a homogeneous particle array can be prepared simply by drying the dispersion, this particle dispersion may be considered as a new ink whose color is generated from the microstructure in the films produced.     

DC conduction mechanism in plasma polymerized vinylene carbonate thin films prepared by glow discharge technique

Electrical glow discharge technique was employed for the preparation of plasma polymerized vinylene carbonate (PPVC) thin films of aluminum/thin film/aluminum sandwich structure at room temperature by a parallel plate capacitively coupled reactor. The structural investigation of the monomer VC and PPVC was performed by Fourier transform infrared spectroscopy. The current density-voltage characteristics follow a power law of the form J α V ⁿ , where n has different values. In the low voltage region 0.85 < n < 1.00 and those in the high voltage region lie between 1.30 < n < 1.75, indicating Ohmic current conduction in the low voltage region and non-Ohmic conduction in the high voltage region. In addition, at higher temperature the current density increased significantly revealing a temperature dependence of the current density. Theoretically calculated values and experimental results of Schottky and Poole-Frenkel coefficients show that the most probable conduction mechanism in the PPVC thin films is of Schottky type.