Plasma Polymer Deposition Research Articles

Fabrication of reverse osmosis membrane via low temperature plasma polymerization

Composite membranes for reverse osmosis were fabricated by low temperature plasma polymerization process. Microporous polysulfone and polypropylene membranes were used as the support for the composite membranes. Various hydrophilic monomers were employed in the plasma polymerization process to form the hydrophilic active layers on the support. Each combination of monomer and support membrane showed its own characteristics. Polysulfone and polypropylene membranes treated with allylamine showed the comparable performances to those of the commercial ones. As plasma polymerization time increased, more plasma polymer was deposited on the support to result in the flux decline and rejection increase. Input power had influence on the plasma polymer deposition rate at low power range especially for monomer-deficient system. Sample got damaged at excess power to reduce the performances in every case. Proper combination of polymerization time and power can secure the economic aspects of the process. At too low monomer flow rate, plasma polymer was not formed enough to cover the surface of the microporous membrane to result in high flux with poor rejection. In the optimum monomer flow rate range highly cross-linked coating layer was formed. When the monomer flow rate exceeded the optimum range, energy transferred to monomer molecule was decreased to result in less cross-linked and unstable layer formation despite the increase of deposition.

Fluorine incorporation in plasma-polymerized octofluorocyclobutane, hexafluoropropylene and trifluoroethylene

The need for increased signal transmission speed and device density in the next generation of multilevel integrated circuits (ICs) places stringent demands on materials performance. There is a requirement for interlayer dielectrics with permittivities under 3 (low κ dielectrics) that have compatibility with copper and copper processing. Plasma polymerization is a solvent-free, room temperature process that can be used to rapidly deposit thin polymer films on a wide variety of substrates. This paper describes the deposition of plasma polymers from several fluorinated monomers (octofluorocyclobutane (OFCB), hexafluoropropylene (HFP) and trifluoroethylene (TrFE)), and evaluates their molecular structures. Films with relatively high F/C ratios were investigated in detail. The refractive index, n, of plasma-polymerized OFCB (PPOFCB), 1.37 at a wavelength of 900 nm, indicates that it has a high frequency permittivity ( n 2) of about 2.0. The plasma fluoropolymers were transparent, yellow films that adhered strongly to the substrates and were deposited at constant deposition rates that ranged from 0.03 μm/min for PPOFCB to 0.34 μm/min for PPHFP. The AFM-determined roughness of PPOFCB on copper is 0.46 nm, half the 0.97 nm roughness of the substrate. The significantly rougher PPTrFE and PPHFP consist of spherical particles from predominantly gas phase polymerizations. The incorporation of fluorine in the polymer is greater and more efficient for PPOFCB and PPHFP than for PPTrFE. For PPOFCB, F/C increases with decreasing W/ F m (where W is the plasma power and F m is the mass flow rate) and, in a less sensitive manner, with increasing pressure. A typical PPOFCB has an F/C of approximately 1.5 and approximately 1.5% oxygen resulting from the reaction of long lived radicals in the plasma polymer with atmospheric oxygen. PPOFCB and PPHFP have similar molecular structures, consisting of random assemblies of fluorinated carbon groups. CF 2 groups are more prevalent in PPOFCB, reflecting the monomer structure and the low W/ F m. CF groups and unsaturation are more prevalent in PPHFP, reflecting the monomer structure and the high W/ F m.

Interfacial processes during plasma polymer deposition on oxide covered iron

The paper gives an insight into the interfacial processes at the iron oxide/polymer interface during the plasma polymer deposition from hexamethyldisilane ((CH 3) 3Si–Si(CH 3) 3). For this purpose an in situ set-up which combines IR-spectroscopy under grazing incidence and quartz crystal micro weighing was used. The deposited plasma polymers had a thickness of less than 10 nm. The surface morphology of the films deposited on flame annealed gold could be visualized by means of atomic force microscopy. The plasma polymers deposited in this study form laterally homogeneous films even at film thicknesses lower than five nanometer. The features of the plasma polymers have a diameter of about 20 nm and a height of about 0.5 nm. During the initial growth of the plasma polymer a formation of covalent bonds at the interface was indicated by IR-spectroscopy. First voltapotential measurements of the plasma modified surface by means of a scanning Kelvin probe show that Fe 3+ states in the iron oxide surface are partly reduced to Fe 2+ during the formation of the first plasma polymer layers.

Aging of 1,3-diaminopropane plasma-deposited polymer films: Mechanisms and reaction pathways

In the course of plasma deposition of organic–polymeric thin films, radicals are incorporated into the growing film. These radicals initiate spontaneous oxidation reactions that continue over many weeks when the plasma polymers are stored in air. These reactions and their products have been previously studied in detail for spectroscopically simple, hydrocarbon-based plasma polymers. In this investigation, the aging of 1,3-diaminopropane (DAP) plasma polymer samples was monitored by XPS and FTIR in order to study how the oxidative reaction pathways might differ in a plasma-deposited material that is initially rich in amine groups. The freshly deposited DAP plasma polymer consisted of a random hydrocarbon network with a considerable amount of unsaturation and a high concentration of nitrogen-containing functional groups, mainly primary/secondary amines and imines. These groups strongly influenced the aging reactions: in contrast to hydrocarbon-based material where hydrogen abstraction and reaction of carbon-centered radicals with in-diffusing oxygen result in a wide range of oxidative products, both XPS and FTIR identified a rather narrow range of products (mainly amides and similar groups) in DAP plasma polymers even after extensive aging for more than 2 years. Reaction routes based on oxidation and/or hydrolysis of nitrogen functional groups, and involving primary as well as secondary reactions, are proposed to account for the spectroscopic data. The structure of the aged DAP plasma polymer appeared to be stable, and did not undergo more extensive oxidation, in contrast to hydrocarbon plasma polymers. In particular, carboxylic acid groups and carbamates were not detected. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2191–2206, 1999

The kinetics of growth of plasma polymer films

A mathematical model for plasma polymer deposition in a tubular reactor was developed. It was the result of the adaptation of a model already used to describe average polymer deposition of an organosilane plasma polymer to a differential equation related to an infinitesimal region of the mentioned reactor. From the solutions of the generated differential equation, the relationship between plasma operational parameters (such as plasma power and monomer mass flow rate) and kinetics of film deposition was analyzed. Additionally, deposition and reactive species profiles along the reactor were calculated.

Surface modification of PAN fibers by plasma polymerization

The deposition of plasma polymers on poly(acrylonitrile) (PAN) fibers has been investigated by X-ray photoelectron spectroscopy and dynamic contact angle measurements. Four polymerizable monomers were examined: tetrafluoromethane (TFM), perfluoropropene (PFP), tetramethyldisiloxane (TMS), and hexamethyldisiloxane (HMS). The deposition rate of TFM was undetectable and the treated fibers exhibited some fluorination and an increase of hydrophilicity, due to posttreatment oxidation after exposure to air. The deposition rate of PFP was quite slow and the formation of an incomplete fluorinated layer was observed, with a remarkable increase of the water advancing contact angles. TMS and more so HMS quickly formed continuous and reproducible polysiloxane layers having pronounced hydrophobic properties. The influence of the position of the fibers in the plasma reactor chamber was also investigated. A good uniformity of deposition was found when the fibers were placed at different points between the electrodes.

In Situ Characterisation of Polymer Surfaces and Thin Organic Films in Plasma Processing

AbstractIn situ sampling techniques are presented for investigation of plasma surface modification of polymers and plasma polymerisation. FTIR spectroscopy (infrared absorption reflection spectroscopy ‐ IRRAS, and attenuated total reflection ‐ ATR) are properly used for characterisation of the changes in the molecular structure of thin polymer films (polystyrene, polyethylene) due to low pressure plasma treatment. The thin films were prepared by dip or spin coating procedures. In the case of plasma polymerisation a novel fibre‐ATR technique is applied to investigate the plasma polymerisation process in the plasma bulk. Results are exemplary shown for plasma polymerisation of styrene. Ellipsometric measurements allowed the characterisation of the thin plasma modified top polymer surface layer or thin deposited plasma polymer films by their refractive index and thickness. It was shown that the applied surface plasmon ellipsometry is very sensitive with respect to the usual ellipsometry for investigation of polymer surface modification. The in situ microgravimetry by means of electronic vacuum microbalance permitted to measure the change of the sample mass in the order of 1 μg during the plasma treatment. The first steps in plasma modification (concurrence between the incorporation of plasma particles and the material etching) were studied.

Fluorescence of plasma polymer films with embedded dye molecules

Plasma polymer thin films with embedded dye molecules (Rhodamine 6G) were deposited by alternating or simultaneous plasma polymerization and dye molecule sublimation. From films with different amounts of embedded dye molecules, fluorescence spectra as well as excitation spectra were recorded. At samples with very low amounts of embedded dye molecules, the fluorescence band was found at λ fl = 550 … 560 nm. At higher dye amounts, the fluorescence band shifts to λ fl = 590 … 600 nm. This was interpreted as the change from embedded isolated dye molecules at low concentrations to dye molecule clusters or nanocrystallites at higher concentrations. The appearance of a second fluorescence band at λ fl = 680 … 700 nm was interpreted as a result of a chemical modification of the Rhodamine 6G molecules during plasma polymer deposition.

Hydrophobic radiofrequency plasma-deposited polymer films: dielectric properties and surface forces

Advancing and receding contact angles for various liquids placed on the surface of thin n-hexane plasma polymer films have confirmed that the surface is hydrophobic; comparable to polyethylene. A waveguide technique has been employed to determine the refractive indices of the plasma polymer films in the visible and near infrared regions of the dielectric spectrum. Along with ESCA data that provide polymer group functionality, this information has been used to estimate the n-hexane plasma polymer density and to construct a simple dielectric permeability function (ϵ(iξ), the dielectric constant at imaginary frequency iξ) for the polymer. The dielectric permeability function and Lifshitz theory have been used to calculate the Hamaker function (including non-retarded Hamaker constants) which should characterise the van der Waals interaction in systems that contain n-hexane plasma polymers. The atomic force microscope (AFM) has been employed to measure the force of interaction between n-hexane plasma polymer films deposited on muscovite mica flat plates and either uncoated silicon nitride AFM tips or n-hexane plasma polymer coated glass spheres. The force versus separation curves have been compared with DLVO theory. The homointeraction between n-hexane plasma polymer coatings in water initially displays a long-range attraction additional to van der Waals interaction. There is evidence that after prolonged immersion in water the thin n-hexane plasma polymer films swell.

Investigation of the plasma polymer deposited from pyrrole

Organic film has been deposited by the plasma polymerization of pyrrole. The elemental composition of the film was determined by elastic recoil detection (ERD) and Rutherford backscattering spectroscopy (RBS). Fourier transform infrared (FT-IR) and X-ray photo-electron spectroscopy (XPS) techniques have been used to characterize it. The reflectance and transmittance data covering the ultraviolet (UV), visible and near-IR regions were used to calculate the complex refractive index, N(ω) = n + ik, using the transfer matrix method. On this basis, a sum rule involving imaginary part of complex dielectric function was applied to estimate the proportion of sp 2 carbon atoms in the deposited plasma polymer film, and the optical properties of the film have been studied in detail.

Properties of Beryllium Loaded Plastic Films

Plasma deposition techniques have been examined for production of air-stable films consisting principally of beryllium and carbon. By plasma polymerization of diethylberyllium, films have been made with Be content above 50%, O content near 1%, excellent composition uniformity and reasonable surface smoothness. It appears necessary, for oxygen stability, to deposit these films at T>250°C; at that temperature, the Be is incorporated, at least in part, as a carbide; the measured film densities—2.1–2.5 g/cm3, are near that of Be2C. Permeability to H2 is sufficent to allow microballon filling at 105°C without subsequent loss of H2 at room temperature.Combined sputtering of Be and deposition of a methane plasma polymer has been found similarly effective in forming beryllium/carbon films with Be content above 50 at. % and O content near 1%. These films have not been as extensively studied.

Plasma polymer deposition from mixture of tetramethoxysilane and oxygen on PET films and their oxygen gas barrier properties

Plasma polymerization of silane compounds has been discussed for deposition of SiOx positron emission tomography (PET) films at room temperature. A mixture of tetramethoxysilane (TMOS) and oxygen containing 60 mol % O2 is a preferable raw material for SiOx formation by plasma polymerization. The deposited plasma polymers consist mainly of Si(SINGLE BOND)O networks with small amount of Si(SINGLE BOND)OH and Si(SINGLE BOND)C groups. A part of Si(SINGLE BOND)O networks in the plasma polymers is distorted by the Si(SINGLE BOND)OH and Si(SINGLE BOND)C groups. The oxygen permeability coefficient for the plasma polymer itself is 2.1 × 10−15 (STP) cm3/cm/cm2/s/cm Hg, which is lower than that for hydrolyzed ethylene-vinylacetate copolymer (Eval) and poly(vinylidene chloride) (Saran). Conclusively, the plasma polymer deposited from the mixture of TMOS and oxygen containing 60 mol % O2 is a material with good oxygen barrier properties. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1031–1039, 1997

Corrosion protection of cold-rolled steel by low temperature plasma interface engineering II. Effects of oxides on corrosion performance of E-coated steels

The effects of oxides on the interfacial chemistry and on the corrosion performance of cathodic E-coat/cathodic plasma polymer of trimethylsilane (TMS)/cathodic plasma treated cold-rolled steel (CRS) systems were investigated. The depth profile analysis by sputtered neutral mass spectroscopy (SNMS) revealed that the nature of the chemical bonds in the plasma polymer/steel interface depends on the presence or the absence of oxides. The cathodic plasma treatment of CRS surface by (Ar + H 2) plasma removes oxides, and the subsequent in situ cathodic polymerization of TMS provides the plasma polymer of TMS/(oxide-free) steel system, in which Fe-C bonds, but no Fe-O bond, are found. The deposition of the same plasma polymer on O 2 plasma pretreated CRS provides the plasma polymer/oxides/steel system, in which Fe-O, but no Fe-C, bonds are found. During the cathodic E-coat deposition, the reducible moieties which exist in the surface state of CRS (including plasma polymer layer and oxides, etc.) are subjected to cathodic reduction. The cathodic reduction could create a weak boundary or defective spots in the interface, which adversely affect the corrosion protecting ability of the coated system. The cathodic E-coat applied directly on the oxide-removed surface of CRS (without Zn phosphate or plasma polymer) showed a better corrosion performance than that applied on the Zn phosphate-chromate CRS, whereas the direct application on the surface with oxides delaminated in the corrosion (GM scab) test. The best result (better than E-coat/Zn phosphate-chromate/EGS) was obtained for E-coat/cathodic polymer of TMS/oxide-free CRS. The corrosion performance of this system was not adversely affected when lead was removed from the E-coat. A cathodic E-coat performs best when the adverse effect of cathodic reduction is minimized.

Oxygen barrier efficiency of hexamethyldisiloxane/oxygen plasma-deposited coating

Oxygen barrier coatings were made by plasma polymer deposition on a polypropylene substrate. Plasma polymer deposition is realized in a low-frequency reactor with hexamethyldisiloxane/oxygen (HMDSO/O2) precursors. The structure and composition of the deposited coating are characterized by density measurements and FTIR spectroscopy. Permeability of the polypropylene, coated with plasma films made from various gas compositions, is interpreted in terms of coating structure and composition. Incorporation of molecular oxygen in the gas phase results in inorganic and dense films. It is shown that the density of the film is the main factor controlling the oxygen barrier effect. © 1996 John Wiley & Sons, Inc.

Plasma polymer thin films of zinc phthalocyanies for NO2 gas sensor device

Zinc phthalocyanines without substituent (ZnPc) and with hydroxymethyl (ZnOc-CH 2 OH), and phthalimidomethyl substituents (ZnPc-CH 2 N[C(O)] 2 Ph) were plasma-polymerized and the application of the deposited plasma polymer films for NO 2 gas sensor device has been discussed. The chemical composition of the deposited plasma polymer films was analyzed by electronic spectroscopy and XPS. The electronic and XPS spectra showed that the plasma polymer films possessed the π-extended electron system and the zinc chelation, although a part of them was degraded by plasma. From the stability of the zinc chelation, the plasma polymer film of ZnPc was chosen as a suitable material for NO 2 gas sensor device. The NO 2 gas sensor device composing of the ZnPc plasma polymer film showed a sensitivity toward NO 2 gas in ranges of 100 to 1000 ppm.

Effect of plasma polymer deposition methods on copper corrosion protection

The behavior of plasma polymer coating for Cu corrosion protection was investigated in dc cathodic polymerization, with and without anode magnetron enhancement, af magnetron glow discharge polymerization, and rf glow discharge polymerization. The combination of visual and scanning electron microscopy observations established general trends in an accelerated wet/dry cycle corrosion testing environment containing 0.1N chloride ions. Dc anodic magnetron cathodic polymerization of TMS offered the best Cu corrosion protection due to an enhanced deposition uniformity and adhesion of the deposited plasma polymer to the Cu substrate. No corrosion was observed after 25 wet/dry cycle accelerated corrosion tests when uncoated Cu suffered a severely generalized attack in one cycle. Superior corrosion protection was also performed by an af plasma polymerized coating of C4F10 + H2 (1 : 1) at a low-energy input density and of methane at high-energy input and high deposition thickness carried out in the range of this study. The application of plasma polymers which showed high water vapor permeation resistance and surface dynamic stability ǵreatly reduced the pitting densities. © 1996 John Wiley & Sons, Inc.

Effect of plasma polymer deposition methods on copper corrosion protection

The behavior of plasma polymer coating for Cu corrosion protection was investigated in dc cathodic polymerization, with and without anode magnetron enhancement, af magnetron glow discharge polymerization, and rf glow discharge polymerization. The combination of visual and scanning electron microscopy observations established general trends in an accelerated wet/dry cycle corrosion testing environment containing 0.1N chloride ions. Dc anodic magnetron cathodic polymerization of TMS offered the best Cu corrosion protection due to an enhanced deposition uniformity and adhesion of the deposited plasma polymer to the Cu substrate. No corrosion was observed after 25 wet/dry cycle accelerated corrosion tests when uncoated Cu suffered a severely generalized attack in one cycle. Superior corrosion protection was also performed by an af plasma polymerized coating of C4F10 + H2 (1 : 1) at a low-energy input density and of methane at high-energy input and high deposition thickness carried out in the range of this study. The application of plasma polymers which showed high water vapor permeation resistance and surface dynamic stability ǵreatly reduced the pitting densities. © 1996 John Wiley & Sons, Inc.

Characterization of the Ageing of Plasma-deposited Polymer Films: Global Analysis of X-ray Photoelectron Spectroscopy Data

A protocol for global analysis of x-ray photoelectron spectra of plasma-deposited polymer films is presented. These materials are difficult to analyse because of the multitude of different chemical groups present. The combination of different primary and secondary binding energy shifts results in relatively broad, featureless photoelectron peaks. The protocol is based on fitting a series of spectra obtained by monitoring the surface composition of a plasma polymer film over extended periods of time after deposition. Information obtained from this first round of curve-fitting is used in the form of additional constraints for a second round of fitting. This leads to a self-consistent procedure which is akin to a global approach to curve-fitting. To illustrate application of this method, results of a study of ann-heptylamine plasma polymer are described. The spectral changes on ageing provided clear evidence for radical-initiated oxidation reactions. These reactions generated additional radicals, which sustained the oxidation process for many months and not only led to substantial incorporation of oxygen into the material (forming a variety of carbon–oxygen functionalities) but also to conversion of most of the existing carbon–nitrogen functionalities to an oxidized form.

Improvement in the adhesion between copper metal and polyimide substrate by plasma polymer deposition of cyano compounds onto polyimide

The surface modification of Kapton film by means of plasma polymer deposition is discussed from the viewpoint of improving the adhesion between copper metal and Kapton film substrate. Plasma polymers of AN (acrylonitrile) and FN (fumaronitrile) were used for the surface modification, and the adhesion between the copper metal and the plasma polymer-coated Kapton film was evaluated by the T-peel strength measurement. The surfaces of peeled layers were analyzed by X-ray photoelectron spectroscopy (XPS) and the failure mode is discussed. The plasma polymer deposition of AN and FN shows an effective improvement in the adhesion between the copper metal and Kapton film; in particular, the AN plasma polymer deposition increased the peel strength 4.3 times. Failure occurred mainly in the Kapton film, and the adhesion between the AN plasma polymer and the Kapton film and that between the copper metal and the AN plasma polymer were found to be quite strong.

Pulsed Plasma Polymerization of Maleic Anhydride

Plasma polymerization of maleic anhydride has been studied using continuous-wave and pulsed glow discharges. The deposited plasma polymer layers have been characterized by X-ray photoelectron spect...