New nanostructured conducting porous polythiophene (PTh) films are directly deposited on substrates at room temperature (RT) by novel atmospheric pressure plasma jets (APPJs) polymerization technique. The proposed plasma polymerization synthesis technique can grow the PTh films with a very fast deposition rate of about 7.0 μm·min⁻¹ by improving the sufficient nucleation and fragment of the thiophene monomer. This study also compares pure and iodine (I₂)-doped PTh films to demonstrate the effects of I₂ doping. To check the feasibility as a sensing material, NO₂-sensing properties of the I₂-doped PTh films-based gas sensors are also investigated. As a result, the proposed APPJs device can produce the high density, porous and ultra-fast polymer films, and polymers-based gas sensors have high sensitivity to NO₂ at RT. Our approach enabled a series of processes from synthesis of sensing materials to fabrication of gas sensors to be carried out simultaneously.

In-situ iodine (I₂)-doped atmospheric pressure (AP) plasma polymerization is proposed, based on a newly designed AP plasma reactor with a single wire electrode that enables low-voltage-driven plasma polymerization. The proposed AP plasma reactor can proceed plasma polymerization at low voltage levels, thereby enabling an effective in-situ I₂ doping process by maintaining a stable glow discharge state even if the applied voltage increases due to the use of a discharge gas containing a large amount of monomer vapors and doping materials. The results of field-emission scanning electron microscopy (FE-SEM) and Fourier transformation infrared spectroscopy (FT-IR) show that the polyaniline (PANI) films are successfully deposited on the silicon (Si) substrates, and that the crosslinking pattern of the synthesized nanoparticles is predominantly vertically aligned. In addition, the in-situ I₂-doped PANI film fabricated by the proposed AP plasma reactor exhibits excellent electrical resistance without electrical aging behavior. The developed AP plasma reactor proposed in this study is more advantageous for the polymerization and in-situ I₂ doping of conductive polymer films than the existing AP plasma reactor with a dielectric barrier.

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.

This paper investigates the properties of thiophene and aniline copolymer (TAC) films deposited by using atmospheric pressure plasma jets copolymerization technique relative to various blending ratios of aniline and thiophene monomer for synthesizing the donor–acceptor conjugated copolymers. Field emission scanning electron microscopy (FE-SEM) and atomic force microscopy are utilized to measure the surface morphology, roughness and film thickness of TAC films. Structural and chemical properties of TAC films are investigated by Fourier transforms-infrared spectroscopy (FT-IR), time of flight secondary ion mass spectrometry, and X-ray photoelectron spectroscopy. FE-SEM images show that the film thickness and nanoparticles size of the TAC films increase with an addition thiophene monomer in the aniline monomer. FE-SEM, FT-IR results show that TAC films are successfully synthesized on glass substrates in all cases. The iodine doped TAC film on the Si substrate with interdigitated electrodes shows the lowest electrical resistance at blending condition of thiophene of 25%.

The use of low-voltage-driven plasma in atmospheric pressure (AP) plasma polymerization is considered as a simple approach to reducing the reactivity of the monomer fragments in order to prevent excessive cross-linking, which would have a negative effect on the structural properties of the polymerized thin films. In this study, AP-plasma polymerization can be processed at low voltage by an AP-plasma reactor with a wire electrode configuration. A bare tungsten wire is used as a powered electrode to initiate discharge in the plasma area (defined as the area between the wide glass tube and the substrate stand), thus allowing plasma polymerization to proceed at a lower voltage compared to other AP-plasma reactors with dielectric barriers. Thus, transparent polyaniline (PANI) films are successfully synthesized. The surface morphology, roughness, and film thickness of the PANI films are characterized by field emission scanning electron microscopy and atomic force microscopy. Thus, the surface of the polymerized film is shown to be homogenous, smooth, and flat, with a low surface roughness of 1 nm. In addition, the structure and chemical properties of the PANI films are investigated by Fourier transform infrared spectroscopy, thus revealing an improvement in the degree of polymerization, even though the process was performed at low voltage.

Here, we proposed a pin-to-liquid dielectric barrier discharge (DBD) structure that used a water-containing vessel body as a dielectric barrier for the stable and effective treatment of aqueous solutions in an open atmosphere. To obtain an intense pin-to-liquid alternating current discharge using a dielectric barrier, discharge characteristics, including the area and shape of a ground-plate-type electrode, were investigated after filling the vessel with equivalent amounts of water. Consequently, as the area of the ground electrode increased, the discharge current became stronger, and its timing became faster. Moreover, we proposed that the pin-to-liquid DBD reactor could be used to decompose phosphorus compounds in water in the form of phosphate as a promising pretreatment method for monitoring total phosphorus in water. The decomposition of phosphorus compounds using the pin-to-liquid DBD reactor demonstrated excellent performance—comparable to the thermochemical pretreatment method—which could be a standard pretreatment method for decomposing phosphorus compounds in water.