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.     

Changes in the surface properties of plasma-modified polyfluoroolefin films during storage and heating

Changes in the wettability and surface contact properties of polytetrafluoroethylene (PTFE) and tetrafluoroethylene-ethylene copolymer films modified in a direct current discharge at the cathode and anode depending on the storage time in air at room temperature and on heating to 200°C have been studied. Changes in the chemical composition of film surfaces have been examined by X-ray photoelectron spectroscopy.     

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.     

Alteration of contact properties and chemical structure of polyethersulfone film surface by direct-current discharge treatment

Changes in the contact properties of the surface of polyethersulfone films modified at the cathode and the anode by dc discharge with varying the treatment time and discharge current have been studied. It has been shown that the treatment imparts hydrophilicity to the films, which persists for a long time. The chemical composition and structure of the surface of the modified films has been examined using X-ray photoelectron spectroscopy.     

Alteration in the surface properties of direct-current discharge-treated tetrafluoroethylene-vinylidene fluoride copolymer films

A change in the contact properties of the surface of tetrafluoroethylene-vinylidene fluoride copolymer films by a dc discharge treatment has been studied, depending on the treatment time and the discharge current. It has been shown that the treatment of the films at the anode and cathode leads to a significant decrease in the contact angle and an increase in the total surface energy and its polar term. The change in the contact properties of the plasma-modified films during storage and heating has been studied as well. The experiments have shown that the formation of polyconjugated structures and crosslinking of macromolecules take place in the film surface layer during long-term treatment at the anode (>60 s, 50 mA), processes that result in an acetone-insoluble layer. The composition and surface structure of the films have been examined by Fourier-transform IR spectroscopy and X-ray photoelectron spectroscopy. The formation of new oxygen-containing groups and double bonds on the polymer surface and crosslinking of macromolecules in the case of anode treatment have been revealed. It has been found experimentally that the discharge treatment increases the peel strength in the Scotch® 810/copolymer film system.     

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.     

Dielectric properties of polytetrafluoroethylene films modified by direct current discharge

Dielectric characteristics of polytetrafluoroethylene (PTFE) films modified by direct current discharge at the anode and cathode have been studied as a function of frequency and temperature. It has been found that the dielectric constant increases slightly as a result of plasma treatment and weakly depends on temperature. It has been shown that the frequency dependences of conductivity at 20°C differ somewhat for the original and treated films, but the closer resemble one another at 80°C, with the difference in the critical conductivity indices becoming more significant.     

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.     

Alteration in the surface properties of direct-current discharge-treated tetrafluoroethylene-ethylene copolymer films

A change in the contact properties of the surface of a tetrafluoroethylene-ethylene copolymer film by treatment of its samples mounted on the cathode and anode in a dc discharge has been studied. It has been shown that the modification leads to a significant improvement in the contact properties of the films owing to the appearance of oxygen-containing polar groups on the polymer surface. The formation of such groups has been proved by X-ray photoelectron spectroscopy. The peel strength of both the untreated and modified films was measured by the T-peel test method.     

Contact Properties and Surface Structure of Polypyromellitimide Films Modified by Direct-Current Discharge

High Energy Chemistry - The contact properties, chemical structure, and surface morphology of polypyromellitimide films modified at the cathode and anode by dc discharge have been investigated. A...     

Adhesive properties of plasma-modified polytetrafluoroethylene films

A procedure was developed for the determination of the adhesion characteristics of the modified surface of thin polymer films, including those treated in a low-temperature plasma, with the use of the Scotch® 810 adhesive tape. The procedure comprises coating the surface to be studied by physical vapor deposition with an aluminum layer of ～100 nm thickness, making an adhesive joint of the film with the Scotch® 810 tape, and T-peel testing of the specimen. Using this procedure, the peel resistance of the initial PTFE film and the film modified at the cathode and the anode in dc discharge was measured.     

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.     

以LiCoO2为阴极的全固态薄膜锂电池的研究

Amorphous and oriented polycrystalline LiCoO2 thin films, used as cathode material for an all-solid-state thin film battery, were fabricated by using RF magnetron sputtering and annealed at different temperatures. The morphology and structure of LiCoO2 thin films were characterized by scanning electron microscopy and X-ray diffraction. All-solid-state thin film batteries, comprised of LiCoO2 cathode films with different structures, lithium phosphorous oxynitride electrolyte film and metallic lithium anode film, was successfully prepared and their properties were examined by chronopotentiometry. Results showed that the structure and crystallinity of the LiCoO2 films strongly influenced the electrochemical performance of all-solid-state thin film lithium batteries. Worth nothing was the battery with an oriented polycrystalline LiCoO2 film it exhibited the best electrochemical performance, and delivered a discharge capacity of ～55.4 μAh/cm2μm. Furthermore, when subjected to over 450 charge/discharge cycles, that battery suffered no obvious fode in capacity.     

Structure and tribological properties of Cu–PU–PTFE composite coatings prepared by low‐energy electron beam dispersion with glow discharge

Polytetrafluoroethylene (PTFE) composite coatings doped copper acetate and polyurethane (PU) were prepared on rubber substrate by low‐energy electron beam dispersion technique. The effects of dopant and glow discharge treatment on the surface morphology, structure and tribological properties of the coatings were investigated. The results showed that Cu–PTFE composite coatings form uniform surface and dense column structure with spherical aggregations under glow discharge treatment. PU coating shows the large size of protuberance structure but PU–PTFE coating presents spherical structure. Both of the coatings become relative dense and smooth after discharge treatment, and Cu–PU–PTFE composite coatings possess a smoother surface and lower polar component of surface energy. Cu doping weakens the crystallinity and ordering degree of composite coatings, but glow discharge increases the ordering degree and branched structure of C―H groups. Friction experiment indicated that Cu fails to improve the wear resistance of PTFE coatings but glow discharge treatment can do it. Cu–PU–PTFE coatings after discharge treatment have the higher wear resistance and lower coefficient of friction. Copyright © 2016 John Wiley & Sons, Ltd.     

阳极支撑层憎水性对被动式直接甲醇燃料电池传质性能的影响

通过测定甲醇渗透率,详细研究了阳极支撑层的聚四氟乙烯（PTFE）含量对全被动式直接甲醇燃料电池（DMFC）甲醇传质和电池性能的影响。 膜电极集合体均使用相同的阳极催化层,膜和阴极。 实验结果表明,随着阳极支撑层PTFE含量的提高,甲醇渗透速率明显减小。 其含量较高时,甲醇传质阻力较大,会导致电池在很低的电流密度下就出现传质控制区。 采用PTFE质量分数为40%的支撑层时,DMFC以9 mol/L甲醇为燃料最大功率密度可达32×10-3 W/cm2,也进一步证明了适当提高阳极支撑层的憎水性,既有助于减少甲醇的渗透,又缓解了阴极的“水淹”问题。     

Study of the physicochemical properties of aminostyrene copolymers modified by plasma treatment

The change in the surface and mechanical properties of styrene-butyl methacrylate-aminostyrene terpolymer films by plasma treatment was investigated. It was found that treatment in a direct-current discharge enhanced the mechanical strength of the terpolymer surface, which can be associated with the crosslinking of linear macromolecules into a three-dimensional network structure. It was shown that the most substantial changes in the mechanical strength are achieved in the case of terpolymer film treatment at the anode.     

The electret properties of tetrafluoroethylene-hexafluoropropylene copolymer films modified in glow discharge

The electret properties of tetrafluoroethylene-hexafluoropropylene copolymer films modified in direct-current discharge were studied. It was shown that the treatment of the films mounted on the anode had an insignificant effect on the relaxation of negative homocharge despite substantial changes in the chemistry of the surface. However, the low-temperature relaxation process responsible for the instability of the electret state in the untreated film is completely suppressed in the case of decay of positive homocharge. Deep traps associated with high-temperature relaxation processes in the polymer are simultaneously eliminated from the spectrum of surface states.     

Magnetron formation of Ni/YSZ anodes of solid oxide fuel cells

Physico-chemical and structural properties of nanocomposite NiO/ZrO₂:Y₂O₃ (NiO/YSZ) films applied using the reactive magnetron deposition technique are studied for application as anodes of solid oxide fuel cells. The effect of oxygen consumption and magnetron power on the discharge parameters is determined to find the optimum conditions of reactive deposition. The conditions for deposition of NiO/YSZ films, under which the deposition rate is maximum (12 μm/h), are found and the volume content of Ni is within the range of 40–50%. Ni-YSZ films reduced in a hydrogen atmosphere at the temperature of 800°C have a nanoporous structure. However, massive nickel agglomerates are formed in the course of reduction on the film surface; their amount grows at an increase in Ni content in the film. Solid oxide fuel cells with YSZ supporting electrolyte and a LaSrMnO₃ cathode are manufactured to study electrochemical properties of NiO/YSZ films. It is shown that fuel cells with a nanocomposite NiO/YSZ anode applied using a magnetron sputtering technique have the maximum power density twice higher than in the case of fuel cells with an anode formed using the high-temperature sintering technique owing to a more developed gas-anode-electrolyte three-phase boundary.     

直接甲醇燃料电池电催化剂性能衰减研究

通过单电池放电试验, 考察了直接甲醇燃料电池(DMFC)电催化剂的性能衰减情况. 透射电镜(TEM)和X射线衍射分析(XRD)结果表明, 放电试验后阳极电催化剂的粒径变化很小, 而阴极电催化剂的粒径则显著增大. DMFC内部的液相环境是促使Pt粒子聚结的主要原因. 阳极催化剂中Ru的存在抑制了Pt粒子的生长. 阳极和阴极电催化剂的电化学表面积(ECSA)在放电后都有所降低, 且下降幅度均高于比表面积(SSA)的下降幅度. 放电过程中阳极电催化剂发生了Ru的流失.     

Charging of Polycarbonate Films in a Direct-Current Discharge

The effect of treatment of Diflon, Makrolon^®, and Lexan^® polycarbonate films in the cathode fall of a dc discharge was studied. Plasma treatment was shown to result in the hydrophilization of the film surface. The dependence of the contact angle on the discharge current and treatment time was examined. It was found that the discharge induced a negative charge on the polycarbonate surface. The surface-charge density was correlated with the contact angle for various treatment conditions. Space charging processes in glow discharge-treated films were investigated using the thermally stimulated relaxation and depolarization techniques. The role of produced charged entities in an increase in the surface energy of modified polycarbonate films was revealed.