Nafion-like thin film plasma-polymerized from perfluorobenzene/SO2 mixture

Plasma polymerization of perfluorobenzene/sulfur dioxide (PFB/SO₂) mixture was investigated by elemental analysis, infrared spectroscopy, and XPS. Plasma polymer films like Nafion were obtained from the plasma polymerization of PFB/SO₂ mixture. The plasma polymerization deposited fluoropolymers with sulfur moieties including sulfonate and sulfonic acid groups. The elemental composition, F/C, and S/C atomic ratio of the formed plasma polymers were 0.65–0.67 and 0.24–0.27, respectively, which were independent of the starting mixture composition. The polymers showed cation-exchange ability of which the capacity was 0.49 meq/g polymer, and initiated the polymerization of pyrrole.     

Plasma polymerization. VII. An esca investigation of the RF plasma polymerization of perfluorobenzene and perfluorobenzene/hydrogen mixtures

The composition and gross structural features of plasma polymers formed in the glow regions of an inductively coupled RF plasma with perfluorobenzene and perfluorobenzene/hydrogen mixtures were investigated by ESCA as a function of the operating parameters. The carbon-to-fluorine stoichiometries of the perfluorobenzene polymers are similar and close to those of the starting material but not of the polymers derived from perfluorobenzene/hydrogen mixtures. The rate of film deposition is dependent on the W/FM parameter. Angular and photon energy-dependent studies confirm the vertical homogeneity of the plasma polymer films investigated.     

Plasma polymerization. II. An ESCA investigation of polymers synthesized by excitation of inductively coupled RF plasma in perfluorobenzene and perfluorocyclohexane

The plasma polymers formed in glow and nonglow regions of an inductively coupled RF plasma with perfluorobenzene and perfluorocyclohexane are discussed as a function of operating conditions of the plasma by means of ESCA. The core levels of the plasma polymers are shown to be strikingly different but characteristic of a well-defined but complex polymerization scheme. For the nonglow regions fluorine incorporation is shown to be greater than for polymers prepared in the glow regions and a preponderance of CF₂ features is apparent. Perfluorobenzene deposits polymer faster than perfluorocyclohexane and changes in component composition of the C_1s profile are studied as a function of operating conditions of the gas plasma.     

ESCA studies of metal-containing plasma polymers. Part I. Incorporation of mercury into plasma-polymerized perfluorobenzene

ESCA was used to examine the structure and bonding of mercury-containing, plasma-polymerized perfluorobenzene. A maximum Hg:C stoichiometry, independent of distillation temperature and power but dependent on substrate temperature, was obtained. Comparison of the plasma polymers of perfluorobenzene and mercury-containing perflurobenzene formed as a function of power, revealed that the C_1s structure of the latter system was not due to the level of mercury incorporated but to sensitized reactions that developed from energy absorption by the mercury in the gas phase.     

Structure–Property Relationship of Thin Plasma Deposited Poly(allyl alcohol) Films

Poly(allyl alcohol) films with a thickness of about 150 nm were deposited by pulse plasma polymerization onto different substrates (inorganic and organic). The structure/property relationships of these samples were studied in dependence on the duty cycle (DC) of the plasma by a broad combination of different techniques and probes. For the first time volume sensitive methods (FTIR and dielectric spectroscopy) are combined with surface analytics by employing XPS for that system. FTIR spectroscopy gives qualitatively the same dependence of the concentration of the OH groups on DC like XPS. The observed differences are discussed considering the different analytical depths of both the methods. The dielectric measurements show that the plasma deposited films are not thermally stable but undergo a post plasma chemical reaction during heating. The results obtained by dielectric spectroscopy are discussed in detail with the data from FTIR and XPS measurements.     

Adsorption of benzene and perfluorobenzene vapor from a flow of moist air by a layer of equilibrium moistened active carbon

The equilibrium adsorption of benzene and perfluorobenzene vapor from a flow of moist air by a layer of active carbon (AC) hydrated to equilibrium were considered. It was ascertained that these organic substances partly displace the water from the adsorptive micropore volume of AC. The equilibrium adsorption values of benzene, perfluorobenzene, and water vapors on AC were calculated. The adsorption of benzene and perfluorobenzene from a flow of moist air by a layer of AC is characterized by volume filling of the micropore adsorption space. This work is part of the research devoted to the study of the dynamics of the adsorption of organic substances from a flow of moist air by a layer of AC hydrated to equilibrium.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1398–1401, August, 1994.     

Deposition of π-Conjugated Polycyanate Ester Thin Films and Their Dielectric Properties

Two kinds of novel π-conjugated polycyanate esters, namely the plasma-polymerized 4-methoxyphenol cyanate ester (PPMPCE) and the plasma-polymerized 4-phenylphenol cyanate ester (PPPPCE), were successfully prepared by plasma polymerization for the first time. The structure and compositions of both plasma polycyanate esters were investigated by Fourier Transform Infrared (FT-IR), X-ray Photoelectron Spectroscopy (XPS) and UV–Visible Absorption Spectra (UV–Vis). The results show that extensively conjugated C=N double bonds were formed in the plasma-deposited cyanate ester thin films, the plasma polymerization of both monomers proceeded mainly via the opening of π-bonds of the O–C≡N functional groups which are further on being formed into a large π-conjugated system, this unique process is noticeably different from the conventional thermal polymerization reaction of cyanate ester monomers. Further dielectric measurement shows that PPPPCE thin film gives a lower dielectric constant comparing to that of the PPMPCE film, and the dielectric constant of both plasma deposited thin films decreased with an increase in measurement frequency.     

Rare-gas insertion compounds of perfluorobenzene: aromaticity of some unstable species

Calculations on the novel argon insertion compounds C6F6Ar(n), n = 1-6, where the argon atoms are inserted into the C-F bonds in perfluorobenzene, suggest that all possible species, with one to six inserted argon atoms, occupy minima on their respective potential energy surfaces. Ring-current plots using the ipsocentric model indicate that there is no disruption of the aromatic pi system upon argon insertion, and consequently all insertion compounds are aromatic according to the magnetic criterion. The barrier height for decomposition of the single-insertion compound, C6F6Ar, into C6F6+Ar is 19.5 kcal/mol at HF6-311G** and 29.5 kcal/mol at B3LYP6-311G**, suggesting that, although clearly thermodynamically unstable, argon-perfluorobenzene insertion compounds may be stable kinetically. Preliminary calculations indicate that other rare gas-perfluorobenzene insertion compounds may also be metastable. Both C6F6Ne and C6F6He are predicted to occupy minima on their respective potential energy surfaces.     

Plasma-Polymerized Thin Films for Enzyme Immobilization in Biosensors

Abstract

Polymer films deposited on thin film noble metal electrodes on silicon chips, utilizing plasma polymerization are shown to be suited for immobilization of enzymes. Glucose oxidase is covalently coupled via amino- or carboxyl-groups of polymer films made by plasma polymerization of 2-amino-benzotrifluoride, acrylic or methacrylic acid. The concentration of these active surface groups increases by after-treatment in an ammonia- or oxygen-plasma. A biosensor consisting of a thin film metal electrode, plasma polymer film and immobilized glucose oxidase shows an amperometric response to glucose with a fast response time.     

Extended Conjugation in Polyaniline Like Structure Prepared by Plasma Polymerization Suitable for Optoelectronic Applications

Plasma polymerization of aniline is carried out in a radiofrequency plasma reactor and the effect of polymerization time is examined in the structural, optical and optoelectronic properties of deposited films. Conjugated structures of polyaniline like films are obtained with unique and broad optical absorption band in the ultraviolet and entire visible region. The width of the absorption band increases and hence the optical band gap decreases with polymerization time. The optical constants are extracted by Swanepoel method and the optical dispersion parameters are determined by employing the Wemple-DiDomenico single oscillator model. The films exhibit similar thermal stability in air and argon atmosphere in the region of interest for optoelectronic applications. The photoluminescence study suggests, like the chemically synthesized polyaniline, the benzenoid units to be responsible for fluorescence. The fluorescence peaks due to defect states confirm the formation of spectroscopic units in the plasma polyaniline films.     

Plasma polymerization of mixed monomer gases

In this paper, plasma polymerization of mixed monomer gases was studied. In the films, the elements derived from each monomer are contained, and they are distributed homogeneously at a certain depth. The films are made up by the copolymers in which both monomers are combined. The chemical compositions of the copolymers can be controlled by changing the proportions of the two monomer gases. The films having gradual compositional change toward depth can be prepared by using a mixture of two monomer gases and changing their proportions during the plasma polymerization. These copolymeric and gradient copolymeric films were formed on porous glass hollow fibers, and gas permeability of these composite membranes was measured. The gradient copolymerization methods are available for the preparation of the membranes for gas separation.     

Surface Modification of Textile Fibers and Cords by Plasma Polymerization

In this paper we report on the treatment of industrial fibers and cords by means of plasma polymerization techniques. Coatings of plasma-polymerized pyrrole or acetylene were deposited on aramid fibers, aramid cords and polyester cords. The equipment was a custom-built semi-continuous reactor operated on a pulsed DC glow discharge. The fibers and cords were tested for adhesion to various polymers such as tire cord skim stock rubber compounds and epoxy adhesives. Standard industrial pull-out force adhesion measurement techniques were used. The deposition conditions of the plasma polymer films were varied within wide limits. It was found that, in general, films deposited under low-power and high-pressure conditions performed better than films prepared under high-power and low-pressure conditions. For some systems pulsing of the discharge power improved the performance further. For all systems studied, the optimized plasma polymer surface modification outperformed current industrial standards. The plasma-polymerized coatings were characterized by various techniques and the excellent performance results are explained in a tentative model based on the molecular structure of the films. This structure was found to be strongly dependent on the discharge conditions.     

Plasma polymerization of styrene with controlled particle energy

A new type of reactor for plasma polymerization was developed in order to achieve an effective control of styrene polymerization process. Electrons and ions were extracted from the radio frequency (rf) glow discharge region to the downstream region to generate plasma polymerization. The energy of extracted ionized particles was controlled by the bias voltage of a screen grid unit. Deposited polymer thin films were analyzed by X-ray photoelectron spectroscopy (XPS) and infrared (IR) spectroscopy. The result showed that the polarity and energy of the extracted particles had considerable effect on the deposition rate and structure of the deposited films. At each bias polarity there was a maximum deposition rate vs. voltage magnitude, and the maximum at the positive voltage was higher. In addition, the bulk aromaticity of the film deposited at the negative bias was lower than at the positive bias; the surface aromaticity of the films was much higher than that of the films prepared by usual rf discharge. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1265–1270, 1998     

Plasma polymerization of cyano compounds

Plasma polymerizations of three cyano compounds—acrylonitrile (AN), 1,2-dicyanoethylene (FN), and tetracyanoethylene (TCE)—were investigated by FT IR and XPS, and the transforamtion of cyano groups during the plasma polymerization was discussed. The results pointed out an aspect of the preparation of plasma films with cyano groups. Plasma polymerizations of AN, FN, and TCE deposited brown or dark brown films that contained carbon, nitrogen, and oxygen. The elemental composition of the plasma films, especially N/C atomic ratio, showed a monomer dependence but no rf power dependence. The plasma films contained amide and amino groups, and ketene-imine and conjugated — C = N — structures as well as cyano groups as nitrogen functionalities, and carbonyl and carboxyl groups as oxygen functionalities. For the preparation of plasma films with cyano groups, compounds with more than two cyano groups themselves are not suitable as monomers. The operation of plasma polymerization under mild plasma conditions at low rf power and in no oxygen atmosphere is favorable for the preparation of plasma films with cyano groups. © 1992 John Wiley & Sons, Inc.     

Plasma Treatment of Polymers to Generate Stable,Hydrophobic Surfaces

Tailoring of polymers for multifaceted applications is an increasing field, whereby most often the surface properties must be adjusted. Therefore, the coating of common polymers by plasma polymerization is a promising way to modify the surface and meet the demands. Beside the tuning of the required surface properties, good adhesion and stability of the films is essential. This work investigates the plasma deposition of pp-HMDSO films on PC and PC/ABS to generate stable, hydrophobic surfaces. By examining the plasma conditions—deposition rate, energy range, and surface topography—ultrathin, stable films with advancing contact angles up to 110° and receding angles exceeding 90° can be designed. Storage of the siloxane films for 1 year in air at ambient conditions exhibits almost no aging. Thus, these films are superior to fluorocarbon films deposited for comparison.     

Atmospheric Pressure Plasma Deposition of Polyfuran

The atmospheric pressure radiofrequency (RF) plasma polymerization of furan was carried out with the objective of synthesizing polyfuran thin film. The structure, compositions and morphology of the plasma deposited polyfuran film were investigated by Fourier transform infrared (FTIR), atomic force microscopy (AFM), ultraviolet‐visible absorption spectroscopy (UV‐vis) and thermogravimetric analysis (TGA). The formation of polyfuran was confirmed using FTIR and UV‐visible analysis. The properties of plasma‐deposited polyfuran were compared with those of chemically synthesized polyfuran. Although the plasma deposited thin film polyfuran shows lower thermal stability than that of chemically synthesized polyfuran. It has better solubility in CHCl₃, also. Thin uniform polyfuran films are obtained in plasma assisted polyfuran deposition, while particles are obtained in chemical polyfuran polymerization.     

仿贝壳结构的自组装有机-无机纳米复合薄膜的制备及结构表征

利用超分子自组装法在玻璃表面制备了聚合前后DMTB/SiO2和DMCB/SiO2复合薄膜.在所制备的复合薄膜中,表面活性剂DMTB和DMCB既作结构导向剂,又作聚合单体.用FTIR,XRD和TEM等表征了薄膜的结构.结果表明,所制备的薄膜具有有机-无机有序交替的层状结构.DMCB/SiO2和DMTB/SiO2复合薄膜有机层与无机层间的距离分别为聚合前3.48和3.44nm,聚合后2.84和2.92nm.     

Chemical Investigation on Various Aromatic Compounds Polymerization in Low Pressure Helium Plasma

Remarkable properties of plasma polymer films are greatly dependent not only on the chemical structure of precursor but also on the reactor design and the deposition conditions. In many industrial applications it is a challenge to control the plasma polymer structure. In this paper we investigate the chemical transformation of various aromatic compounds, such as activation and fragmentation of substituent-part, aromatic ring opening, during plasma polymerization process. Polymerized films are deposited in a low-frequency capacitively coupled plasma-enhanced chemical vapour deposition reactor, working at low pressure. The chemical composition of plasma-polymerized films is elucidated by Fourier-transform infrared spectroscopy, solid-state carbon-13 nuclear magnetic resonance spectroscopy, and X-ray photoelectron spectroscopy. Based on spectroscopic measurements, the intermediary reactions during film growth may be presumed.     

Dimethylketene: Plasma-generated gas-phase precursor of photoluminescence chromophores in plasma polymerized films of methyl methacrylate and tetramethyl-1,3-cyclobutanedione

Gas-phase chemistry of tetramethyl-1,3-cyclobutanedione (TMCB) and formaldehyde plasmas have been studied within situ Fourier Transform Infrared (FTIR) Spectroscopy. Our previous work indicated that methyl methacrylate (MMA) dissociates to intermediate species of dimethylketene (DMK) and formaldehyde in MMA plasmas. This investigation of DMK dimer (TMCB) and formaldehyde plasmas is a continuation of our effort to understand the plasma polymerization chemistry of MMA. FTIR spectra confirmed the presence of DMK in TMCB plasmas and a polymeric thin film was deposited. Formaldehyde plasmas did not deposit any film for our experimental condition. Furthermore, plasma polymerized TMCB (PPTMCB) films exhibit UV photoluminescence similar to that of PPMMA films. Therefore, DMK is proposed to be the gas-phase precursor of photoluminescence chromophores in both PPMMA and PPTMCB films. Paper based on the results presented during the workshop of the Engineering Research Center for Plasma-Aided Manufacturing held in Madison, Wisconsin, in Spring 1996.     

Film Chemistry Control and Growth Kinetics of Pulsed Plasma-Polymerized Aniline

The polymerization of aniline under continuous and pulsed RF-plasma conditions is studied using the same plasma reactor. The effects of input power, on and off-times, frequency and duty cycle variations on the growth kinetics and on the chemical structure of the obtained layers are examined. The chemical structure of the films is characterized using Fourier Transform Infra-Red, X-ray photoelectron and UltraViolet?CVisible spectroscopies. The thickness of the films is determined by profilometry. The results show a strong dependence of film chemistry and deposition rates on the discharge power and on-time. The film deposited by pulsed plasma grows mainly during the plasma-on period. Furthermore, this work shows that the retention of aromatic rings can be evaluated by Fourier transform infrared analysis whereas oxidation degree of plasma polyaniline can be determined by X-ray photoelectron and UV?CVis spectroscopies.