Ching-Yuan Tsai

Static Water Contact Angle Analysis of Cyclonic Atmospheric Pressure Plasma-Activated Polycarbonate

Polycarbonate (PC) films were activated using cyclonic atmospheric pressure plasma. The experimentally measured gas phase temperature was from 30 to 95 °C, demonstrating that this cyclonic atmospheric pressure plasma can treat heat-sensitive polymeric materials at the low temperatures. The surface hydrophilicity changes of cyclonic atmospheric pressure plasma-treated PC films were determined by water contact angle analysis. The activation effects of plasma operational parameters including treatment time, plasma power, and distance of nozzle to substrate on the PC surface features were investigated. The glow feature and luminous plasma species in the cyclonic atmospheric pressure plasma were identified by optical emission spectroscopy (OES). Cyclonic atmospheric pressure plasma-activated PC films showed a significant decrease in water contact angle. In this investigation, we developed an innovative technique for chamberless polymeric surface activation by this atmospheric pressure plasma processing.

Surface Characterization of Argon/Methane Mixture Atmospheric-Pressure Plasma-Treated Filtration Poly(Vinylidene Fluoride) Membrane and Its Flux Enhancement

Poly(vinylidene fluoride) (PVDF) was extensively used as the filtration material because of its stable thermal and chemical capabilities. However, hydrophobic surface of PVDF membrane induces the restriction for its manufacturing uses. In light of this, the plasma at atmospheric pressure was used for the PVDF membrane surface treatment with argon/methane gas mixture in this paper. The variation in hydrophilicity of the plasma-treated PVDF membrane was analyzed by the contact angle analysis. It shows that this plasma is operative in membrane surface modification. The argon/methane gas mixture cyclonic plasma-treated PVDF membrane also showed the enhanced filtration behavior rather than the untreated PVDF membrane.

Surface Modification of Polypropylene Membrane by RF Methane/Oxygen Mixture Plasma Treatment

The hydrophilic surface modification of micro-porous polypropylene (PP) membranes is achieved by low-pressure 13.56 MHz RF methane (CH4)/oxygen (O2) gas mixture plasma treatment. The changes in surface wettability and surface free energy were examined by static contact angle analysis. The static water contact angle of the plasma modified membrane notably decreased with increases in treatment time and plasma power. The obvious increase in the surface energy of polypropylene membranes due to CH4/O2 mixture gas plasma treatments was also observed. Optical emission spectroscopy (OES) was used to analyze the chemical species of CH4/O2 mixture gas plasma treatment. The variations in the surface morphology and chemical structure of the micro-porous PP membranes were confirmed by confocal laser scanning microscopy (CLSM), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) measurements. XPS analysis showed significantly higher surface concentrations of oxygen functional groups for CH4/O2 mixture gas plasma-modified polypropylene membrane surfaces than for the originally unmodified polypropylene membrane surface. The experimental results show the important role of chemical species in the interaction between a CH4/O2 mixture gas plasma and a membrane surface, which can be controlled by surface modification to tailor the hydrophilicity of the membrane to the requirements of various applications.

Large-Area Organosilicon Film Deposition Using Cyclonic Atmospheric Pressure Glow Discharge

Cyclonic atmospheric pressure plasma is developed for chamberless deposition of organosilicon thin films from argon/hexamethyldisoxane (HMDSO) mixtures. The surface properties of the resulting plasma films were investigated as a function of RF plasma power. Film characterization was performed by static contact angle measurement, scanning electron microscopy (SEM), atomic forced microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). It was found the RF plasma power is the key factor that to affects the film growth in the atmospheric pressure plasma chemical vapor deposition process. SEM and AFM results indicated that a smooth, continuous, and uniform surface of organosilicon thin films can be formed at a relatively low plasma power input. XPS indicated that atmospheric-pressure plasma-deposited organosilicon films present mainly inorganic characteristics. This study shows a potential of chamberless film growth at atmospheric pressure to form organosilicon thin films for large-area deposition.

Tailoring Surface Properties of Polymeric Separators for Lithium-Ion Batteries by 13.56 MHz Radio-Frequency Plasma Glow Discharge

The hydrophilic surface modification of the polymeric separator is achieved by low-pressure 13.56 MHz radio-frequency Ar and He gas plasma treatments. The changes in surface hydrophilicity and surface free energy were examined by static contact angle analysis. The static water contact angle of the plasma-modified polymeric separator particularly decreased with the increase in treatment time. An obvious increase in the surface energy of polymeric separators owing to the crosslinking by activated species of inert gases effect of monatomic-gas-plasma treatments was also observed. Optical emission spectroscopy was carried out to analyze the chemical species generated after Ar and He gas plasma treatments. The variations in the surface morphology and chemical structure of the polymeric separators were confirmed by scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy (XPS) measurements. XPS analysis showed significantly higher surface concentrations of oxygen functional groups for monatomic-gas-plasma-modified polymeric separator surfaces than for the unmodified polymeric separator surface. The experimental results show the important role of chemical species in the interaction between Ar and He gas plasmas and the polymeric separator surface, which can be controlled by surface modification to tailor the hydrophilicity of the polymeric separator.

Glow Characterization in Low-Pressure Radio-Frequency

The glow characteristics and deposited film structures of fluorocarbon monomers in radio-frequency glow discharges are investigated using CH₂F₂ and C₂H₂F₄, which were compared to hydrocarbon monomer such as CH₄. The glow was characterized and investigated by optical photography, optical emission spectroscopy, and Fourier transform infrared spectrometry. The glow differences were attributed to the nature of the luminous gas phase in respect to polymer-forming species.

\hbox{CH}_{2} \hbox{F}_{2}

The glow characteristics and optical emission features of octafluorocyclobutane radio frequency plasmas with various gas flow rates were investigated. The plasma glow was characterized by optical photography and optical emission spectroscopy. The glow differences were attributed to the nature of the luminous gas phase with respect to polymer-forming species and etching species.

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The glow characteristics and optical emission features of 13.56-MHz radio frequency (RF) argon plasmapoly(vinylidene fluoride) membrane surface interactions were studied. The glow of RF plasma surface modification was characterized by optical photography and optical emission spectroscopy. The glow differences were attributed to the nature of the luminous gas phase in respect to chemically reactive species.

\hbox{C}_{2}\hbox{H}_{2}\hbox{F}_{4}

Polypropylene nonwoven materials have foundenormous usefulness in many applications. In this paper, the cyclonic plasma processing at atmospheric pressure was used to determine the surface treatment effect. The change of hydrophilicity was determined by contact angle analysis. The nonwoven polypropylene (NWPP) surface became greatly hydrophilic when exposed to the cyclonic plasma at atmospheric-pressure. A major effect in the surface free energy of material surface due to crosslinking via activated species of inert gases effect was observed. The variations in the chemical structure and surface morphology of the NWPP were confirmed by X-ray photoelectron spectroscopy (XPS) and scanning electron microscope detections. The XPS detection reveals considerably more surface elemental composition of oxygen atoms for cyclonic plasma-modified NWPP.

Plasma Deposition Systems

Electrospun-poly(vinylidenefluoride cohexafluoro-propylene) (PVDF-HFP) micro-fiber membrane is modified by cyclonic atmospheric pressure plasma. The gas phase temperature of cyclonic atmospheric pressure plasma state was around 30°C to 90°C, indicating this plasma can treat electrospun PVDF-HFP membrane without harmful heat damages. The surface properties of cyclonic atmospheric pressure plasma-treated electrospun PVDF-HFP micro-fiber membranes were examined by the static contact angle analysis. The influence of plasma treatment time on the electrospun PVDF-HFP micro-fiber membrane surface was studied. It was found that such cyclonic atmospheric pressure plasma is useful in PVDF-HFP micro-fiber membrane surface modification, the reduced water contact angle was observed from 137° to less than 30° with only 1 min. treatment time. Scanning electron microscopy (SEM) was used to determine the changes in surface feature of the PVDF-HFP micro-fiber membrane due to plasma treatment. In this investigation, it shows an innovative method for electrospun micro-fiber membrane surface modification by cyclonic atmospheric pressure plasma.