Plasma Polymerized Methyl Methacrylate Research Articles

The Correlation of Plasma Characteristics to the Deposition Rate of Plasma Polymerized Methyl Methacrylate Thin Films in an Inductively Coupled Plasma System

A plasma system attached with one internal coil (for generating inductively coupled plasma) and two sputtering carbon targets was set up to deposit PP-MMA (plasma polymerized methyl methacrylate) thin films. PP-MMA was used as a model material in the present study. In the experiment, the working pressure and Ar/MMA flow ratio were varied, which resulted in the change in plasma conditions as well as the deposition rates. The optical emission spectroscopy (OES) method was applied to identify the presence of the excited species related to the fragmented monomer. In addition, the electron temperature and electron density were determined using the modified Boltzmann plot and line-ratio method, according to the measured OES spectra. The deposition rate of the PMMA film was then correlated with the determined plasma characteristics. To determine the vibrational modes of the deposited PP-MMA films, Fourier transformed infrared spectrometry (FTIR) was used. The highest deposition rate of PP-MMA could be obtained with the optimized working pressure and Ar/MMA volume ratio. This could be related to the plasma characteristics that contribute to the fragmentation of the monomer in the plasma.

Application of Spectroscopic Analysis for Plasma Polymerization Deposition onto the Inner Surfaces of Silicone Tubes

In the current study, plasma-polymerized methyl methacrylate (PP-MMA) generation on the inner surface of a silicone tube was performed in a capacitively coupled discharge reactor. The possibility of generating plasma inside the tube was analyzed and calculated by using optical emission spectroscopy (OES). A hollow cathode model was first proposed to determine whether plasma discharge would be generated inside the tube in the low-pressure regime. Since the ignition of plasma inside the tube is necessary for the initiation of polymerization processes, the sheath thickness was calculated analytically. To achieve the goal, the electron temperature and density of plasma should be determined beforehand. In this study, the electron temperature and plasma density were measured and calculated according to OES spectra using both the modified Boltzmann plot and the line-ratio method. The results reveal that the occurrence of plasma inside the tube can be achieved if the tube’s inner diameter is greater than two times the thickness of the sheath. The effect of methyl methacrylate (MMA) monomer concentration on sheath thickness, and, hence, plasma generation and deposition, was investigated in the presence of argon plasma and MMA monomer. According to the study, one could control the ignition of plasma discharges inside the tube followed by plasma polymerization deposition. The OES method was also applied to identify the presence of the excited species related to the fragmented monomer. The deposition of PP-MMA films on the inner surface of the tube was confirmed via attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy.

Synthesis and Properties of Plasma-Polymerized Methyl Methacrylate via the Atmospheric Pressure Plasma Polymerization Technique.

Pinhole free layers are needed in order to prevent oxygen and water from damaging flexible electrical and bio-devices. Although polymerized methyl methacrylate (polymethyl methacrylate, PMMA) for the pinhole free layer has been studied extensively in the past, little work has been done on synthesizing films of this material using atmospheric pressure plasma-assisted electro-polymerization. Herein, we report the synthesis and properties of plasma-PMMA (pPMMA) synthesized using the atmospheric pressure plasma-assisted electro-polymerization technique at room temperature. According to the Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and time of flight-secondary ion mass spectrometry (ToF-SIMS) results, the characteristic peaks from the pPMMA polymer chain were shown to have been detected. The results indicate that the percentage of hydrophobic groups (C–C and C–H) is greater than that of hydrophilic groups (C–O and O–C=O). The field emission-scanning electron microscope (FE-SEM) and thickness measurement results show that the surface morphology is quite homogenous and amorphous in nature, and the newly proposed pPMMA film at a thickness of 1.5 µm has high transmittance (about 93%) characteristics. In addition, the results of water contact angle tests show that pPMMA thin films can improve the hydrophobicity.

Organic Memory Device with an Organic Memory Layer of Plasma Polymerized Styrene

A floating-gate-type organic memory device was designed and fabricated by modifying a thin- film transistor structure. Thin films of plasma-polymerized methyl methacrylate (ppMMA) and plasmapolymerized styrene (ppS) were prepared for use as the functional thin film in an organic memory device. The ppMMA thin film was utilized as both an insulating and a tunneling layer. Two types of memory layers were utilized: (1) ppS and (2) vacuum evaporated Au. The fabricated devices were examined by using current-voltage measurements made using the double-sweep procedure. The memory window and the retention time of the memory devices were comparatively investigated. The device with the ppS memory layer revealed a memory window of 19 V and showed a retention time of over 2 h. We confirmed that ppS could be utilized as a memory layer for a floating-gate-type organic memory device.

Floating-Gate Type Organic Memory with Organic Insulator Thin Film of Plasma Polymerized Methyl Methacrylate

To fabricate organic memory device by entirely dry process, plasma polymerized methyl methacrylate (ppMMA) thin films were prepared and they were used as both tunneling layer and gate insulator layer in a floating-gate type organic memory device. The ppMMA thin films were prepared with inductively coupled plasma (ICP) source combined with stabilized monomer vapor control. The ppMMA gate insulator thin film revealed dielectric constant of 3.75 and low leakage current of smaller than 10-9 A/cm. The floating-gate type organic memory device showed promising memory characteristics such as memory window value of 12 V and retention time of over 2 h, where 60 V of writing voltage and -30 V of erasing voltage were applied, respectively.

Process Condition Considered Preparation and Characterization of Plasma Polymerized Methyl Methacrylate Thin Films for Organic Thin Film Transistor Application

Process Condition Considered Preparation and Characterization of Plasma Polymerized Methyl Methacrylate Thin Films for Organic Thin Film Transistor Application

Process Condition Considered Preparation and Characterization of Plasma Polymerized Methyl Methacrylate Thin Films for Organic Thin Film Transistor Application

Plasma polymerized methyl methaclylate (ppMMA) thin films were prepared with various process conditions such as inductively coupled plasma (ICP) power, substrate bias power, working pressure, substrate heating temperature, substrate position, and monomer flow rate. Thickness, surface morphology, dielectric constant, and leakage current of the ppMMA thin films were investigated for application to organic thin film transistor as gate dielectric. Deposition rate of over 8.6 nm/min, dielectric constant of 3.4, and leakage current density of 8.9 ×10-9 A/cm-2 at electric field of 1 MV/cm were achieved for the ppMMA thin film prepared at the optimized process condition: plasma power of RF 100 W; Ar flow rate of 20 sccm; working pressure of 5 mTorr; substrate temperature of 100 °C; substrate position of 100 mm. The ppMMA thin film was then applied to pentacene based organic thin film transistor (OTFT) device fabrication. The OTFT device with 80 nm thick pentacene semiconductor layer showed field effect mobility of 0.144 cm2 V-1 s-1 and threshold voltage of -1.72 V.

Preparation and Characterization of Plasma Polymerized Methyl Methacrylate Thin Films as Gate Dielectric for Organic Thin Film Transistor

Plasma polymerized methyl methacrylate (ppMMA) thin films were deposited by plasma polymerization technique with different plasma powers and subsequently thermally treated at temperatures of 60 to <TEX>$150^{\circ}C$</TEX>. To find a better ppMMA preparation technique for application to organic thin film transistor (OTFT) as dielectric layer, the chemical composition, surface morphology, and electrical properties of ppMMA were investigated. The effect of ppMMA thin-film preparation conditions on the resulting thin film properties were discussed, specifically O-H site content in the pMMA, dielectric constant, leakage current density, and hysteresis.

Effect of electrode geometry on the uniformity of plasma-polymerized methyl methacrylate coatings

Plasma polymerization is widely used to deposit functionalized coatings which properties can be tuned by different operational parameters. Although plasma-deposited coatings have many interesting properties, the influence of these parameters on the polymerization process is not yet well understood. In this study, plasma-polymerized methyl methacrylate (MMA) coatings are produced and carefully planned experiments are conducted to evaluate the influence of discharge power and electrode geometry on the chemical composition and thickness of the deposited films. For this purpose, polymerization processes are carried out in two plasma reactors with different electrode geometries (parallel plate versus mesh-to-plate) and the influence of discharge power is examined for both reactor types. This study reveals that the chemical composition of the deposited films is strongly influenced by the power of the discharge: at high powers, the coatings contain less ester functional groups, which is most likely due to monomer fragmentation at these elevated powers. It is also shown in this work that the reactor set-up strongly determines the uniformity of the deposited films: in the parallel plate reactor, film thickness, surface morphology and chemical composition depend on the location of the substrate in the discharge region, while in the mesh-to-plate reactor the deposited films are physically and chemically uniform. Taking into account the latter statement, the mesh-to-plate reactor might have important industrial applications.

Polymer coatings to functionalize carbon nanotubes

Multi-walled carbon nanotubes (MWCNTs) were modified by plasma polymerization with methyl methacrylate (MMA) and allylamine (AA) as monomers. Conditions of the MMA and AA plasma polymerization processes in a specially designed reactor and the plasma-polymerized MMA and AA coatings were studied. The chemical composition of the surface was analyzed by X-ray Photoelectron Spectroscopy (XPS); the polymer deposited on the CNTs surface was visualized by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), while Fourier Transform Infrared spectroscopy (FTIR) allowed checking for the chemical structure of deposited plasma polymers (PP). In this work, we show that plasma functionalization creates C=O and C–O–C functional groups, or C–NH2 at the MWCNT surface, as a result of polymer deposited during the MMA or AA plasma treatments, respectively.

Plasma polymerized methyl methacrylate gate dielectric for organic thin-film transistors

A pentacene-based organic thin-film transistor (OTFT) device with plasma polymerized methyl methacrylate (ppMMA) dielectric film was fabricated. The ppMMA showed a higher dielectric constant of 3.86 than that of conventionally processed PMMA and a MIS capacitor with the ppMMA revealed negligible hysteresis in C – V curves. The OTFT device with the ppMMA dielectric showed a field-effect mobility of 0.08 ± 0.02 cm 2 V −1 s −1 in the saturation region, a lower threshold voltage of −3 ± 0.15 V, a sub-threshold slope of 0.959 ± 0.05 V/decade, an on/off current ratio ( I on / I off ) of 1.0 × 10 4 ± 0.10, and a lower operating voltage of −10 V.

Surface modification of carbon nanofibers (CNFs) by plasma polymerization of methylmethacrylate and its effect on the properties of PMMA/CNF nanocomposites

AbstractCarbon nanofibers (CNFs) were modified via plasma polymerization using methyl methacrylate (MMA) as monomer and used as reinforcements for polymethyl methacrylate (PMMA). Conditions of the MMA plasma process in a specially designed reactor and plasma-polymerized methyl methacrylate (PPMMA) films were studied. The study involved varying the process time at a constant plasma power of 100 W and a constant MMA flow rate (0.15 cm3 per min). Nanocomposites of PPMMA-coated CNFs and PMMA were prepared with 0.5, 1.0, 2.0, 4.0 and 8.0 %wt of treated CNFs. The effect of the MMA plasma on the CNFs was analyzed. Dispersion of the modified CNFs was evaluated in several solvents. The results confirmed a change in hydrophobicity of the treated CNFs. The inclusion of treated CNFs exhibited substantial impact on the properties of the PMMA/CNF nanocomposites. The thermal and mechanical properties of the PMMA/CNF composites were examined. It was found that the thermal stability increased by about 8% and the Young´s modulus significantly enhanced by as much as 178% when compared to PMMA with no CNFs.

Deposition of polymethyl methacrylate on polypropylene substrates using an atmospheric pressure dielectric barrier discharge

In this work, an atmospheric pressure glow-like dielectric barrier discharge in helium with small admixtures of methyl methacrylate (MMA) is used for the deposition of thin polymethyl methacrylate (PMMA) films. The effect of discharge power and feed composition (monomer concentration) on film properties has been investigated by means of Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The results are described by defining a W/ FM value, where W is the discharge power, F the monomer flow rate and M is the molecular weight of the monomer. It is shown in this paper, that the deposition rate and the chemical composition of the deposited film change with varying W/ FM values. At low W/ FM values, high deposition rates of up to 2 nm/s are observed and the plasma-polymerized MMA chemically resembles the conventionally synthesized PMMA. In contrast, using high W/ FM values (≥102 MJ/kg) leads to lower deposition rates (as low as 0.9 nm/s), while the plasma-polymerized MMA films contain less ester groups and a larger amount of ether and/or alcohol groups. One should therefore carefully choose the deposition parameters in order to obtain a high deposition rate and a high retention of ester groups in the plasma-polymerized MMA films.

Poly(methyl methacrylate) Films Deposited via Non‐Equilibrium Atmospheric Pressure Plasma Polymerization Using Argon as Working Gas

AbstractA non‐equilibrium atmospheric pressure plasma torch using argon (Ar) for sustaining plasma has been developed, and it was used to deposit plasma polymerized methyl methacrylate (PPMMA) films. The chemical structure and composition of the films obtained were examined by FT‐IR and XPS analyses. It was found that, when raising the concentration of vaporized monomer to a certain level into the plasma, the plasma transitioned from a filamentary to a glow‐like discharge, this resulting in a high retention of the monomer structure. Since the optical emission spectroscopy (OES) study of the plasma did not show any new excited species formed at higher concentrations of the monomer, it is clear that the fragmentation degree of the monomer in the plasma phase was quite low.magnified image

Improved performance of organic light-emitting devices with plasma treated ITO surface and plasma polymerized methyl methacrylate buffer layer

Transparent indium-tin-oxide (ITO) anode surface was modified using O 3 plasma and organic ultra-thin buffer layers were deposited on the ITO surface using 13.56 MHz rf plasma polymerization technique. A plasma polymerized methyl methacrylate (ppMMA) ultra-thin buffer layer was deposited between the ITO anode and hole transporting layer (HTL). The plasma polymerization of the buffer layer was carried out at a homemade capacitively coupled plasma (CCP) equipment. N, N′-Diphenyl- N, N′-bis(3-methylphenyl)-1,1′-diphenyl-4,4′-diamine (TPD) as HTL, Tris(8-hydroxy-quinolinato)aluminum (Alq 3) as both emitting layer (EML)/electron transporting layer (ETL), and aluminum layer as cathode were deposited using thermal evaporation technique. Electroluminescence (EL) efficiency, operating voltage and stability of the organic light-emitting devices (OLEDs) were investigated in order to study the effect of the plasma surface treatment of the ITO anode and role of plasma polymerized methyl methacrylate as an organic ultra-thin buffer layer.

Carbon dioxide sorption in conventional and plasma polymerized methyl methacrylate thin films

CO2 sorption isotherms are reported for plasma polymerized methyl methacrylate (ppMMA) and the conventionally polymerized analog, poly(methyl methacrylate) (PMMA). The isotherms are measured at temperatures ranging from 20 to 95°C and analyzed using the Dual-Mode sorption model. In the lower temperature range, the magnitude of the Henry's law (kD) and the coupled Langmuir component parameters (C′Hb) for both materials are similar. The expected collapse of the Langmuir sorption mode in conventional PMMA near the glass transition temperature is clearly observed. However, the Langmuir component in the plasma polymerized material does not diminish in the same manner as that for the conventional polymer analog. In contrast with the ppMMA, the PMMA materials are shown to exhibit significant dilation for extended conditioning times at high CO2 pressures. The response of the isotherms for the two materials to ‘quench’ and ‘slow cool’ thermal conditioning protocols are similar, but small.

Protective layer using plasma polymerized thin films in ac-plasma display panel

Flat panel displays have recently received much attention in research and development as alternatives to the cathode ray tube (CRT). The plasma display panel (PDP) is considered a promising candidate for commercial development. The performance of an ac PDP is influenced strongly by the surface plasma characteristics on the protective layer. The objective of this study was to examine the potential use of a polymerized thin film to replace MgO conventionally use for this protective layer. This thin film was formed using an interelectrode capacitively coupled plasma polymerization apparatus using methyl methacrylate (MMA) to create a polymerized PPMMA plasma polymerized methyl methacrylate (PPMMA). Both the functional groups of PMMA and PPMMA were found in the analysis using Fourier transform infrared. The polymerization rate of plasma polymer increased as a function of the plasma power and decreased as a function of the system pressure using scanning electron microscopy (SEM). The plasma polymerized thin films showed high transparency of over 98% and had a secondary electron emission coefficient that was higher than the MgO thin films 0.02–0.14 over 50–150 V. The characteristics of the PPMMA made it a very attractive candidate protective layer. The next step in its qualification is to study sputtering and operational characteristics in demonstrative panel.

A complete dry lithography using plasma processes

Abstract This work was carried out to develop a pattern, on the nanometer scale, using plasma polymerization and plasma etching. It is also aimed at developing a resist for the nano process and a vacuum lithography process. The thin films of plasma polymerization were fabricated by the plasma polymerization of inter-electrode capacitively coupled gas flow system. After delineating the pattern, an accelerating voltage of 30 kV, varying the dose in the range 1–500 μC/cm2, the pattern was developed with dry type and formed by plasma etching. Analyzing the molecule structure using Fourier transform-infrared spectrometry (FT-IR), it was confirmed that the thin films of plasma polymerized methylmethacrylate+styrene+tetramethyltin (PPMST) contain the functional groups of the methylmethacrylate+styrene+tetramethyltin (MST) monomer. The thin films of PPMST had a highly cross-linked structure resulting in a higher molecular weight than the conventional resist. The deposition rate of the PPMST thin films was 230–600 A/min as a function of 50–200 W power and 200–60 A/min as a function 0.1–0.7 Torr pressure. The etching rate of the thin films of PPMST was 875–3520 A/min as a function of 50–200 W power and 2870–360 A/min as a function of 0.2–0.7 Torr pressure. The sensitivity and contrast of the PPMST resist were 5 μμC/cm2 and 4.5 respectively. The resolution of the resist was 50 nm and various patterns having sizes 0.2 m, 100 nm, 70 nm , 50 nm and 35 nm and 20 nm were successfully formed.

In situ FTIR investigation of MMA plasmas, plasma-polymerized films, and reaction mechanisms

Methyl methacrylate (MMA) plasmas and plasma-polymerized methyl methacrylate (PPMMA) films were studied in situ with FTIR and FTIR/ATR (attenuated total reflection) in an r.f. capacitively coupled glow discharge. A statistically designed experiment was conducted by varying the r.f. power, process pressure, and MMA flow rate. MMA plasma fragments were identified from the gas-phase FTIR measurements. They include the intermediate species such as dimethylketene, formaldehyde, allene, and propene; small hydrocarbons such as acetylene, methane, and ethylene; and oxygenates such as carbon dioxide, carbon monoxide, and methanol. Statistical analysis techniques (correlation analysis, analysis of variance and regression analysis) were used on both gas and film data. Gas-phase reaction mechanisms are proposed, and the relationship between the gas and film data is investigated to understand the film deposition chemistry. The deposition rate is positively correlated to the relative concentrations of MMA fragments which are identified as the major film precursors in the deposition process. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 587–602, 1998

In situ infrared spectroscopy as a real time diagnostic for plasma polymer film deposition

In situ Fourier transform infrared spectroscopy (FTIR)/attenuated total reflection (ATR) was used to study the deposition of plasma polymerized methyl methacrylate (PPMMA) film. Real time absorption spectra of PPMMA films were obtained at a time resolution of 20–30 s which is mostly limited by the low optical throughput and low signal-to-noise ratio. Postplasma dynamics observed in the system demonstrate the need for an in situ and real time film diagnostic technique. This letter reports the use of this diagnostic on plasma deposited polymers.