Plasma polymerization of tetramethyldisiloxane by a magnetron glow discharge

Plasma polymerization of tetramethyldisiloxane by a magnetron glow discharge was studied. The glow discharge was created between parallel electrodes with a 10 kHz electric power source with a superimposed magnetic field using permanent bar magnets. Polymers were deposited onto moving substrates placed on the surface of a rotating disc located in between the electrodes. The deposition rates were determined with a quartz crystal thickness monitor placed on the plane of the rotating disc and just outside the edge of the disc. The current-voltage relationship observed for plasma polymerization of the monomer depends on the monomer feed rate and the conditioning of the electrodes or the establishment of a steady state surface in the polymer-forming plasma, which also depends mainly on the monomer feed rate. Consequently, plasma polymerization cannot be correlated to single operational parameters such as the discharge current, the power or the monomer feed rate in a simple manner. However, when the deposition rate was expressed as R_p/FM, where R_p is the polymer deposition rate, F is the monomer feed rate and M is the molecular weight (FM is thus the monomer mass feed rate), it was found that R_p/FM is uniquely related to the parameter W/FM where W is the discharge power in Watts. It was shown that many polymer properties were also determined mainly by the same composite parameter. It was also found that the presence of O₂ gas in the monomer feed reduced the carbon content in the polymer and made the surface more hydrophobic while O₂ plasma treatment of the plasma polymer rendered the surface more hydrophilic.     

Effects of deposition parameters on SiCln (n=0-2) densities in SiCl4 glow discharge plasma

The relative densities of SiCl_n (n=0-2) in SiCl₄ radio frequency (rf) glow discharge plasma are measured by mass spectrometry. The effects of discharge parameters, including rf power, discharge pressure, substrate temperature and SiCl₄ flow rate on the relative densities of SiCl_n (n=0-2) are investigated in detail. The experimental results demonstrate that the relative densities of SiCl_n (n=0-2) in SiCl₄ plasma are dependent strongly on these discharge parameters. An optimum configuration of discharge parameters (low rf power, high discharge pressure, low substrate temperature and low flow rate), which enhanced the formation of SiCl_n (n=0-2) radicals, was searched. Further, researching of SiCl_n (n=0-2) spatial distribution for seeking a suitable deposition condition is beneficial for understanding the deposition mechanism of thin films.     

RF-Ar等离子体对聚乙烯薄膜的表面改性

采用射频辉光放电氩等离子体,在工作压力为20 Pa、功率为30W的条件下对低密度聚乙烯薄膜进行了不同时间的表面处理。借助静态接触角、X射线光电子能谱仪、原子力显微镜、差示扫描量热仪对薄膜改性前后的性能进行了表征及分析。研究结果表明:氩等离子体短时间(20 s)处理便可以有效改善薄膜表面的亲水性,处理时间大于20 s后接触角的变化并不明显;处理后的薄膜表面引入了大量的含氧及少量的含氮官能团;薄膜表面所形成的交联层阻挡了极性基团的翻转,有效延长了接触角的时效性;薄膜的表面形貌和结晶度发生了变化。     

Heating of polymer substrate by discharge plasma in radiofrequency magnetron sputtering deposition

The substrate used for the thin film deposition in a radiofrequency magnetron sputtering deposition system is heated by the deposition plasma. This may change drastically the surface properties of the polymer substrates. Deposition of titanium dioxide thin films on polymethyl methacrylate and polycarbonate substrates resulted in buckling of the substrate surfaces. This effect was evaluated by analysis of atomic force microscopy topography images of the deposited films. The amount of energy received by the substrate surface during the film deposition was determined by a thermal probe. Then, the results of the thermal probe measurements were used to compute the surface temperature of the polymer substrate. The computation revealed that the substrate surface temperature depends on the substrate thickness, discharge power and substrate holder temperature. For the case of the TiO₂ film depositions in the radiofrequency magnetron plasma, the computation indicated substrate surface temperature values under the polymer melting temperature. Therefore, the buckling of polymer substrate surface in the deposition plasma may not be regarded as a temperature driven surface instability, but more as an effect of argon ion bombardment.     

Preparation of gas separation membranes by plasma polymerization with fluoro compounds

Plasma polymerization coatings were applied for the preparation of gas separation membranes. Mainly fluoro compounds were used as coating materials. The membranes showed good separation characteristics with high flux for gaseous systems. The plasma polymerization composite parameter given by W/FM plays an important role in obtaining excellent separation characteristics. The correlation between the conversion rate DR/FM, where DR is the deposition rate of plasma polymer, and W/FM is useful to consider the plasma polymer character under the different plasma polymerization conditions (discharge power W and monomer flow rate F). The proper conditions for membrane preparation lie in the intermediate region between the region in which the monomer flow rate is deficient and that in which the discharge power is deficient. Furthermore, the plasma polymerization coatings with the higher molecular weight monomer gave the higher separation characteristics. Plasma polymer composite membranes in this study showed superiority for the molecular sieve type of separation over the solution-diffusion type of separation.     

Glow discharge polymeric films: preparation,structure, properties and applications

Glow discharge polymerization is one of the most important vacuum techniques to produce thin polymer films. Thin films made by a glow discharge have some profitable properties like being very dense without pinholes, thermally stable and highly insulating. The films can be deposited on any substrate. These and other properties promote the application of such films. The deposition parameters influence the structure and the properties of the films. In some cases the influence of the used monomer and of the deposition parameters is of the same order. The polymerization was carried out with several aromatic mononitriles and dinitriles and their structure and properties were investigated. Glow discharge polymers from the structural point of view have much in common with a polymer which was partially thermally degraded. Structure and properties of the mononitriles and dinitriles glow discharge polymers show remarkable differences. From these differences a quantumchemical calculation of the monomers provides a possible explanation. The main application of thin films made by glow discharge polymerization is to passivate surfaces. Some other applications of interest are known, but to increase this field of application more knowledge is necessary of the relationship between the polymerization process and the chemical structure.     

含氮化合物的等离子共聚研究

报道了含氮化合物如吡咯（Ｐyr)、吡啶（Ｐd)、四氢吡咯（Ｐyd)和六氢吡啶（Ｐpd)等离子（Plasma)聚合研究结果,它们具有相对不同的聚合行为。同时不研究了催化剂Ｉ２对Ｐlasma聚合的加速作用,可使吡咯Ｐlasma聚合速率提高４０％－６０％。     

Surface modification of nanoporous alumina membranes by plasma polymerization

The deposition of plasma polymer coatings onto porous alumina (PA) membranes was investigated with the aim of adjusting the surface chemistry and the pore size of the membranes. PA membranes from commercial sources with a range of pore diameters (20, 100 and 200?nm) were used and modified by plasma polymerization using n-heptylamine (HA) monomer, which resulted in a chemically reactive polymer surface with amino groups. Heptylamine plasma polymer (HAPP) layers with a thickness less than the pore diameter do not span the pores but reduce their diameter. Accordingly, by adjusting the deposition time and thus the thickness of the plasma polymer coating, it is feasible to produce any desired pore diameter. The structural and chemical properties of modified membranes were studied by scanning electron microscopy (SEM), atomic force microscopy (AFM) and x-ray electron spectroscopy (XPS). The resultant PA membranes with specific surface chemistry and controlled pore size are applicable for molecular separation, cell culture, bioreactors, biosensing, drug delivery, and engineering complex composite membranes.     

Properties of tin/plasma polymer nanocomposites

Thin composite layers (tin in plasma polymer matrix) were prepared in a stainless steel vacuum chamber. An RF powered magnetron with tin target was used to excite the discharge and to activate the monomer species (n-hexane). The gas mixture introduced comprised Ar and n-hexane vapours. The properties of the films and chemical composition were characterized by AFM (surface morphology), TEM and Electron tomography (bulk structure characterization), XPS and FTIR spectroscopy (chemical composition analyses). Current-voltage characteristics were measured to examine the electrical properties of the layers and their dependence on the deposition parameters.     

Poly(2-substituted-2-oxazoline) surfaces for dermal fibroblasts adhesion and detachment

The thermoresponsive surfaces of brush structure (linear polymer chains tethered on the surface) based on poly(2-isopropyl-2-oxazoline)s and copolymers of 2-ethyl-2-oxazoline and 2-nonyl-2-oxazoline were obtained using the grafting-to method. The living oxazoline (co)polymers have been synthesized by cationic ring-opening polymerization and subsequently terminated by the reactive amine groups present on the surface. The changes in the surface morphology, philicity and thickness occurring during surface modification were monitored via atomic force microscopy, contact angle and ellipsometry. The thickness of the (co)poly(2-substituted-2-oxazoline) layers ranged from 4 to 11 nm depending on the molar mass of immobilized polymer and reversibly varied with the temperature changes. This confirmed thermoresponsive properties of obtained surfaces. The obtained polymer surfaces were used as a support for dermal fibroblast culture and detachment. The fibroblasts’ adhesion and proliferation on the polymer surfaces were observed when the culture temperature was above the cloud point temperature of the immobilized polymer. Lowering the temperature resulted in the detachment of the dermal fibroblast sheets from the polymer layers, which makes these surfaces suitable for the treatment of wounds and in skin tissue engineering.     

Preparation of plasma poly(1-isoquinolinecarbonitrile) thin film and its ultrafast nonlinear optical property

How to get a uniform, defect-free, and reproducible conjugated polymer thin films is now becoming the main fabrication problem for the practical application of these materials as the fast switches and modulators in opto-electronic devices. In this research, a novel plasma-polymerized 1-isoquinolinecarbonitrile (PPIQCN) thin film was prepared by plasma polymerization under different glow discharge conditions. The effect of the discharge power on the chemical structure and surface compositions of the deposited PPIQCN films was investigated by Fourier transform infrared (FTIR), UV-Visible absorption spectra and X-ray photoelectron spectroscopy (XPS). The results show that a high retention of the aromatic ring structure of the starting monomer in the deposited plasma films is obtained when a low discharge power of 10 W was used during film formation. In the case of higher discharge power of 30 W, more severe monomer molecular fragmentation can be observed, which results in a decrease in the effective conjugation length of PPIQCN film. The morphology characterized by atomic force microscopy (AFM) indicates that a fine, homogenous PPIQCN film could be obtained under a relatively low discharge power. A femtosecond time-resolved optical Kerr effect technique at a wavelength of 820 nm has been applied to investigate the third-order nonlinearity of the plasma PPIQCN film. For the first time, a non-resonant optical Kerr effect and ultrafast response of the PPIQCN film was observed.     

等离子体聚合工艺对聚合沉积速率的影响

利用等离子体聚合的方法对两种有机单体(正丙醇和丙烯醇)进行了等离子体聚合,成功地在Si基体上沉积了高分子薄膜.利用XPS研究了薄膜的结构和不同工艺对沉积速度的影响.研究表明,随着功率的增加或工作气压的增加,沉积速率增加;偏压的增加使等离子体聚合的沉积速率减小.研究还发现,丙烯醇含有双键结构,其沉积速率比正丙醇大.     

Investigation of atmospheric-pressure plasma deposited SiOx films on polymeric substrates

The novel technique of plasma chemical vapor deposition without using vacuum chamber was investigated to deposit SiOx films on polymeric substrates through tetraethoxysilane (TEOS)/Air atmospheric-pressure plasma (APP) glow discharge. Depending on the proper deposition parameters, thin and smooth SiOx films on polycarbonate substrates were prepared. The atmospheric-pressure plasma deposited SiOx films obtained the desirable transparency in the visible and increased absorption in UV region. The surface characteristics of APP deposited SiOx films were examined by various surface analysis methods including FTIR, XPS, and SEM. It is shown that SiOx films exhibited low porosity and admirable hardness for optical applications.     

Metal-containing fluoropolymer films produced by simultaneous plasma etching and polymerization: The series of perfluoroalkanes nF2n+2 (n = 1,2,3,4)

Simultaneous etching and polymerization were studied for a series of perfluoroalkanes in an r.f. plasma system. The incorporation of metal (removed from the excitation electrode) into the fluoropolymer films (formed on the grounded electrode) is demonstrated and the metal content is shown to be related to the relative rates of etching and polymer deposition. Determination of the film structures was achieved by electron spectroscopy for chemical analysis which, coupled with the analysis of the plasma gas phase by direct mass spectrometric sampling, led to the identification of the primary precursors to polymerization. The major precursors can be summarized as (CF₂)_n (n=1,2,3,4) for all systems studied, although at low power levels their relative importance is shown to be a function of the injected perfluoroalkane.     

Optical and chemical characterization of thin TiNx films deposited by DC-magnetron sputtering

Thin titanium nitride (TiN_x) films were deposited on silicon substrates by means of a reactive DC-magnetron plasma. Layers were synthesized under various conditions of discharge power and nitrogen flows in two operation modes of the magnetron (the so-called “balanced” and “unbalanced” modes). The optical constants of the TiN_x films were investigated by spectroscopic ellipsometry (SE). X-ray photoelectron spectroscopy (XPS) was used to determine the relative atomic concentration and chemical states of the TiN_x films. The density and thickness of the films have been investigated by means of grazing incidence X-ray reflectometry (GIXR). The results of the layer analyses were combined with plasma investigations carried out by means of energy resolved mass spectrometry (ERMS) under the same conditions. It is shown that the magnetron mode has a clear influence on the titanium deposition rate and the incorporation of nitrogen into the layers.     

Influence of oxygen and nitrogen plasma treatment on polyethylene terephthalate (PET) polymers

In this paper we present surface modification of polyethylene terephthalate (PET) polymer, which is commonly used as synthetic vascular graft. Surface modification was made by oxygen and nitrogen plasma at different treatment times. Plasma was created by means of an RF generator at a discharge power of 200 W and gas pressure fixed at 75 Pa. The surface of PET polymer was modified in order to achieve improved attachment of fucoidan, which is a bioactive coating with antithrombogenic properties. In our study we analysed chemical modification of plasma treated surfaces by X-ray photoelectron spectroscopy (XPS), while the changes in morphology and surface roughness were observed with atomic force microscopy (AFM). Our results indicate that attachment of fucoidan is improved by oxygen plasma treatment, especially due to surface roughening.     

Deposition and structure of gold-containing plasma-polymerized halocarbon films

Simultaneous plasma polymerization of chlorotrifluoroethylene and magnetron sputtering of gold in an r.f. (20 MHz) glow discharge were used for the deposition of composite thin films. The spectra emitted from the discharge (250–450 nm) were found to be formed by the superposition of a CF₂ radical band system and the gold spectral lines. The emission characteristics could be related to the film composition. It was shown using AES depth profile analysis and IR spectroscopy that (1) the amount of halogen atoms in the layers decreases with increasing gold concentration and (2) the film surface is not representative of the bulk of the layers at higher gold volume fractions. The changes in the film microstructure are explained in terms of a bombardment of the growing layers by energetic particles, most probably negative ions.     

射频等离子体放电的宏观参数与PET表面改性的关系

通过射频等离子体放电，采用O2，CF4及CH4／CF4混合气体等离子体对PET表面进行处理。改变射频等离子体放电的宏观参数，如放电时间、放电功率、电极间距离和复合参数，详细地研究了这些参数对PET表面改性的影响。结果表明：碳氟混合气体等离子体在PET表面的沉积速率为正值，在PET表面形成了聚合物；而O2和纯CF4气体的沉积速率为负值，两者在PET表面产生刻蚀效应。增加等离子体放电功率和放电时间，聚合或刻蚀效果更明显；而增加电极间距离和复合参数，聚合或刻蚀效果明显减弱。     

Plasma-polymerized alkaline anion-exchange membrane: Synthesis and structure characterization

After-glow discharge plasma polymerization was developed for alkaline anion-exchange membranes synthesis using vinylbenzyl chloride as monomer. X-ray photoelectron spectroscopy and attenuated total reflection Fourier transform infrared spectroscopy were used to characterize the chemical structure properties of plasma-polymerized membranes. Ion-exchange capacities of quaternized poly(vinylbenzyl chloride) (QPVBC) membranes were measured to evaluate their capability of hydroxyl ion transport. A mechanism of plasma polymerization using VBC as monomer that accounts for the competitive effects of free radicals polymerization and plasma ablation in the plasma polymerization process was proposed. Our results indicate that plasma discharge power influences the contents of functional groups and the structure of the plasma polymer membranes, which attribute to the coactions of polymerization and ablation. The properties of uniform morphology, good adhesion to the substrate, high thermal stability and satisfying anion conduction level suggest the potential application of QPVBC membrane deposited at discharge power of 20 W in alkaline direct methanol fuel cells.