Pressure Plasma Polymerization Research Articles

Direct grafting of microwrinkled hydrogels by atmospheric-pressure plasma polymerization: Going simple and environmentally friendly

The simple, direct fabrication of pH-responsive hydrogel coatings with microstructured wrinkles from a monomer mixture containing 2-hydroxyethyl methacrylate and 2-(diethylamino)ethyl methacrylate, grafted on silicon substrates via atmospheric-pressure plasma polymerization is reported. The process allows the synthesis of hydrogels with high conversion degree, which preserve the functionalities of both monomers as proven by XPS and FT IR analysis. Atomic force microscopy was conducted to characterize the wrinkle dimension, which revealed an increase of the wrinkle wavelength λ and amplitude A with the film’s thickness. The chemical and morphological properties of the hydrogel films are preserved, even after immersion in deionized water for several days, indicating the high stability of the plasma-polymerized hydrogels. The simplicity of atmospheric-pressure plasma polymerization to deposit responsive hydrogels which are highly stable and having tunable properties as “materials on demand”, will certainly extend the applications of plasma-based hydrogels especially for biomedical applications.

The investigation of deposited organic carbon‐silicon films using cyclonic atmospheric pressure plasma polymerization

AbstractBackgroundThe upgrading of atmospheric‐pressure plasma polymerization process, the detailed investigation of atmospheric‐pressure plasma polymerization deposited organic carbon‐silicon film features is essential to obtain the further understandings into the optimizing coating techniques.AimThis investigation demonstrates plasma cyclone deposited film features with adjusting argon gas flow rate and HMDSN monomer flow rate.MethodThis study utilized the plasma cyclone system to polymerize a carbon‐silicon film. In this study, Optical Emission Spectroscopy (OES) was employed as a diagnostic tool to indirectly inspect the chemical composition of the atmospheric‐pressure plasma polymerization's glow discharge by detecting the photo‐emitting species. The Contact Angle Goniometer, ATR‐FTIR, AFM, and XPS were used to measure the surface properties of the films deposited by plasma cyclone.ResultsThe static contact angle results show that most of the deposited films obtain the divergent contact angle values with adjusting argon gas flow rate and HMDSN monomer flow rate. ATR‐FTIR results show that argon gas flow rate and HMDSN monomer flow rate dominate the porosity of plasma cyclone deposited film surface. XPS and AFM analyses also detect the comparable trend of physicochemical characteristics of organic carbon‐silicon film with adjusting argon gas flow rate and HMDSN monomer flow rate. In summary, the organic carbon‐silicon films can be successfully polymerized by plasma cyclone.ConclusionsThe results refer that the organic carbon‐silicon film deposition on vanadium redox flow battery separator surface improved the electrolyte uptake of the cyclonic‐plasma‐coated separators was larger than that of a commercial separator.

Atmospheric Pressure Plasma Polymerization of Carvone: A Promising Approach for Antimicrobial Coatings

Medical devices are often vulnerable to colonization by nosocomial pathogens (bacteria), leading to infections. Traditional sterilization methods may not always be effective, and as a result, alternative options are being explored to prevent microbial contamination. Recently, scientists are emphasizing using plant-derived essential oils that possess inherent antibacterial properties to produce antimicrobial coatings using plasma polymerization technology carried out at atmospheric pressure (AP). This approach shows promise compared to other coating strategies that need several processing steps, including a high-vacuum system, and are laborious, such as the immobilization of antimicrobial materials on precoated layers in the low-pressure plasma polymerization approach. The present study demonstrates the potential of AP plasma polymerization for producing thin films with excellent antibacterial properties and surface characteristics. The resulting coatings are stable, smooth, and have high wettability, making them ideal for repelling bacteria. The calculated zeta potential and deposition rate for the films are also favorable. These AP plasma-polymerized thin films created from carvone show a reduction rate of more than 90% for Escherichia coli and Staphylococcus aureus bacteria. Our computational docking studies also reveal strong binding interactions between the original carvone monomer and both bacteria. The study suggests that these AP plasma-produced coatings have great potential as antibacterial coatings for biomedical devices.

Nanostructured Polyaniline Films Functionalized through Auxiliary Nitrogen Addition in Atmospheric Pressure Plasma Polymerization

Polyaniline (PANI) was synthesized from liquid aniline, a nitrogen-containing aromatic compound, through the atmospheric pressure (AP) plasma process using a newly designed plasma jet array with wide spacing between plasma jets. To expand the area of the polymerized film, the newly proposed plasma jet array comprises three AP plasma jet devices spaced 7 mm apart in a triangular configuration and an electrodeless quartz tube capable of applying auxiliary gas in the center of the triangular plasma jets. The vaporized aniline monomer was synthesized into a PANI film using the proposed plasma array device. The effects of nitrogen gas addition on the morphological, chemical, and electrical properties of PANI films in AP argon plasma polymerization were examined. The iodine-doped PANI film was isolated from the atmosphere through encapsulation. The constant electrical resistance of the PANI film indicates that the conductive PANI film can achieve the desired resistance by controlling the atmospheric exposure time through encapsulation.

Effects of O2 gas addition on enhancing lithium electrochromic performance of flexible WFexTayOz1Cz2Nz3 films synthesized by cold atmospheric pressure plasma polymerization

Improved lithium electrochromic (EC) performance of flexible organo-tungsten-iron-tantalum oxynitride (WFexTayOz1Cz2Nz3) films by rapidly deposited onto flexible (60 Ω/□ polyethylene terephthalate/indium tin oxide) substrates at a short exposure duration of 54 s, with O2 gases added to precursor vapors, and injected into air plasma jet, was undertaken. O2 gases addition for synthesis of WFexTayOz1Cz2Nz3 films by cold atmospheric pressure plasmas polymerization was proven to significantly enhance optical modulation at a wavelength of 850 nm from 59.7% without addition of O2 gases to 70.0% with addition of O2 gases at a flow rate of 0.5 sccm. WFexTayOz1Cz2Nz3 films synthesized with O2 gas addition at a flow rate of 0.5 sccm exhibit fast coloration and bleaching responses as the short coloration time up to 5.1 s and the short bleaching time up to 3.7 s were obtained. Surface morphology and surface compositions of WFexTayOz1Cz2Nz3 films were analyzed by FESEM and XPS to investigate how the O2 gas addition enhanced the lithium EC properties.

Antibacterial Thin Films Deposited from Propane-Butane Mixture in Atmospheric Pressure Discharge.

Antibacterial coatings on biomedical instruments are of great interest because they can suppress bacterial colonization on these instruments. In this study, antibacterial polymeric thin coatings were deposited on teflon substrates using atmospheric pressure plasma polymerization from a propane-butane mixture. The plasma polymerization was performed by means of surface dielectric barrier discharge burning in nitrogen at atmospheric pressure. The chemical composition of plasma polymerized propane-butane films was studied by energy-dispersive X-ray spectroscopy (EDX) and FTIR. The film surface properties were studied by SEM and by surface energy measurement. The EDX analysis showed that the films consisted of carbon, nitrogen and oxygen from ambient air. The FTIR analysis confirmed, in particular, the presence of alkyl, nitrile, acetylene, imide and amine groups. The deposited films were hydrophilic with a water contact angle in the range of 13-23°. The thin film deposited samples were highly active against both S. aureus and E. coli strains in general. On the other hand, the films were cytocompatible, reaching more than 80% of the cell viability threshold compared to reference polystyrene tissue.

Control strategies for atmospheric pressure plasma polymerization of fluorinated silane thin films with antiadhesive properties

AbstractFinding proper strategies to control plasma polymerization processes is a crucial aspect to produce thin films with tailored characteristics. In this work, the validity of the Yasuda parameter W/FM (W: discharge power and FM: precursor feed rate) as a controlling parameter for a polymerization process assisted by an atmospheric pressure single electrode plasma jet and the aerosolized fluorinated silane precursor trimethoxy(3,3,3‐trifluoropropyl)silane is demonstrated. The properties of thin films deposited under different W/FM values are discussed using attenuated total reflectance—Fourier transform infrared (ATR‐FTIR) spectroscopy, X‐ray photoelectron spectroscopy (XPS), water contact angle (WCA) measurements, and scanning electron microscopy (SEM). Results suggest the presence of two deposition domains as a function of W/FM (an energy‐deficient domain and a monomer‐deficient domain), each inducing coatings with different chemical and physical properties. Furthermore, coatings deposited under the same W/FM values exhibit similar characteristics regardless of the power and feed rate values adopted. Considering the potential use of the deposited coatings to increase the antiadhesive properties of implantable medical devices, preliminary results on coatings' antiadhesive activity against Pseudomonas aeruginosa and Staphylococcus aureus are presented.

Superhydrophobic and superoleophilic surfaces prepared by one-step plasma polymerization for oil-water separation and self-cleaning function

Efficient superhydrophobic and superoleophilic thin films for oil-water separation and self-cleaning were prepared using the atmospheric-pressure plasma polymerization of hexamethyldisiloxane (HMDSO). A dielectric barrier discharge (DBD) plasma jet with argon (Ar) was used for the deposition of the functional thin films onto several substrates. The oil-water separation membrane was synthesized by the plasma polymerization of HMDSO on fabric and offset printing paper. The superhydrophobic coatings were deposited on glass to demonstrate their self-cleaning ability. The hydrophobicity of the thin films was found to vary significantly, depending on the operating parameters such as the deposition time, applied voltage, and gas flow rate. The gaseous shield of the plasma jet also affected the hydrophobicity to a large extent. Nitrogen (N2) rather than inert gases such as Ar and He exhibited an excellent shielding effect against the interference of ambient air on the plasma jet. The wettability of the glass was completely switched from superhydrophilic to superhydrophobic with the water contact angle (WCA) reaching 165° and the sliding angle about 2°. In addition, superoleophilicity was obtained with the oil contact angle (OCA) reaching 0° under the optimal operating conditions.

Optimization of Atmospheric Pressure Plasma Jet with Single-Pin Electrode Configuration and Its Application in Polyaniline Thin Film Growth.

This study systematically investigated an atmospheric pressure plasma reactor with a centered single pin electrode inside a dielectric tube for depositing the polyaniline (PANI) thin film based on the experimental case studies relative to variations in pin electrode configurations (cases I, II, and III), bluff-body heights, and argon (Ar) gas flow rates. In these cases, the intensified charge-coupled device and optical emission spectroscopy were analyzed to investigate the factors affecting intensive glow-like plasma generation for deposition with a large area. Compared to case I, the intense glow-like plasma of the cases II and III generated abundant reactive nitrogen species (RNSs) and excited argon radical species for fragmentation and recombination of PANI. In case III, the film thickness and deposition rate of the PANI thin film were about 450 nm and 7.5 nm/min, respectively. This increase may imply that the increase in the excited radical species contributes to the fragmentation and recombination due to the increase in RNSs and excited argon radicals during the atmospheric pressure (AP) plasma polymerization to obtain the PANI thin film. This intense glow-like plasma generated broadly by the AP plasma reactor can uniformly deposit the PANI thin film, which is confirmed by field emission-scanning electron microscopy and Fourier transform infrared spectroscopy.

Promotion of biofilm production via atmospheric-pressure plasma-polymerization for biomedical applications

The ability of bacteria to form biofilms that enhance their resistance to disinfectants and antibiotics is a matter of concern in the fields of food processing and healthcare. Since culture conditions in laboratories are not exactly the same as in the real environments where bacterial infection takes place, developing models that rapidly produce biofilm on test surfaces has become an interesting topic of research. In this work, Pseudomonas aeruginosa biofilm production on polystyrene Petri dishes was promoted by atmospheric-pressure plasma-polymerization of 3-(Aminopropyl)triethoxysilane (APTES). Different coatings were deposited varying only the number of plasma-polymerization passes. Biofilm productions, ranging from 157% to 457% relative to that on the uncoated dishes, were quantified after 24-h incubation. According to morphological and chemical characterizations, the APTES precursor promoted biofilm production in several ways: providing amines that facilitated the attachment of more bacterial cells than on uncoated dishes, inducing an oxidative stress to the attached bacteria that caused an overproduction of extracellular polymeric substances, and generating siloxane-based particles that formed a granular pattern that facilitated bacterial accumulation in its valleys. Comparing the coatings, a direct relationship was identified between the number of plasma-polymerization passes, the roughness and the biofilm production.

Improvement of Nanostructured Polythiophene Film Uniformity Using a Cruciform Electrode and Substrate Rotation in Atmospheric Pressure Plasma Polymerization.

In atmospheric pressure (AP) plasma polymerization, increasing the effective volume of the plasma medium by expanding the plasma-generating region within the plasma reactor is considered a simple method to create regular and uniform polymer films. Here, we propose a newly designed AP plasma reactor with a cruciform wire electrode that can expand the discharge volume. Based on the plasma vessel configuration, which consists of a wide tube and a substrate stand, two tungsten wires crossed at 90 degrees are used as a common powered electrode in consideration of two-dimensional spatial expansion. In the wire electrode, which is partially covered by a glass capillary, discharge occurs at the boundary where the capillary terminates, so that the discharge region is divided into fourths along the cruciform electrode and the discharge volume can successfully expand. It is confirmed that although a discharge imbalance in the four regions of the AP plasma reactor can adversely affect the uniformity of the polymerized, nanostructured polymer film, rotating the substrate using a turntable can significantly improve the film uniformity. With this AP plasma reactor, nanostructured polythiophene (PTh) films are synthesized and the morphology and chemical properties of the PTh nanostructure, as well as the PTh-film uniformity and electrical properties, are investigated in detail.

Functional Thin Films Synthesized from Liquid Precursors by Combining Mist Chambers and Atmospheric-Pressure Plasma Polymerization

For the creation of thin films, the use of precursors in liquid phase offers a viable alternative when these chemicals are sensitive to high temperatures and phase changes. However, it requires appropriate liquid handling and deposition technologies capable of dispensing the fluid homogeneously to produce a uniform thin film. We report different tailor-made mist chamber designs integrated in an atmospheric-pressure plasma polymerization process for the synthesis of functional thin polymer films from liquid precursors. A systematic investigation, evaluated by performance indicators, is presented on the characteristics and suitability of metallic 3D-printed mist chambers depending on inner volume, geometry and surface post-treatment, for the deposition of a thin liquid monomer film. To assess the quality of the subsequently obtained plasma-polymerized (pp) films, their properties were characterized in terms of thickness, chemical composition, surface morphology and stability in aqueous environment. It was found that the specification of the mist chambers along with the plasma process parameters influences the pp film’s thickness, surface morphology and degree of monomer conversion. This study is one of the first demonstrations of a controllable process able to tune the cross-linked polymeric chains of plasma-polymers at atmospheric pressure, highlighting the opportunities of using mist chambers and plasma technology to discover tailored organic thin films to materials sciences and life sciences.

Inhibition of biofilm formation on polystyrene substrates by atmospheric pressure plasma polymerization of siloxane‐based coatings

AbstractBiofilms pose important economic and health risks in biomedical applications and in food industries. In this study, coatings that reduce the biofilm formation of Pseudomonas aeruginosa on polystyrene cell culture plates are deposited by plasma polymerization of (3‐aminopropyl)triethoxysilane using an atmospheric pressure plasma jet system at three different power levels. Surface characterizations and quantification of biofilm formation during 1 week after deposition suggest that the higher concentration of oxygenated carbon groups on the coated samples than on uncoated ones can induce higher levels of oxidative stress in the bacteria in contact with the coatings. This causes an initial overproduction of extracellular polymeric substances that can avoid further bacterial attachment and biofilm formation at later cycles of biofilm development.

Synthesis and characterization of poly(pyrrole-co-aniline) copolymer using atmospheric pressure plasma polymerization

This paper investigates the characteristics of poly(pyrrole-co-aniline) copolymer (PYPAN) films deposited by using an atmospheric pressure plasma (APP) polymerization relative to various concentrations of aniline and pyrrole monomers. The surface morphology and structure properties of PYPAN films are observed to strongly depend on the pyrrole concentration (%), which is confirmed by Field emission-scanning electron microscopy (FE-SEM), Fourier transforms-infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and time of flight-secondary ion mass spectrometry (ToF-SIMS). In particular, it is observed that the PYPAN film grown at an optimal pyrrole concentration condition (that is, aniline 25% and pyrrole 75%) shows a lower electrical resistance and higher deposition rate.

Improvement of the Uniformity and Electrical Properties of Polyaniline Nanocomposite Film by Addition of Auxiliary Gases during Atmospheric Pressure Plasma Polymerization.

The morphological and chemical properties of polyaniline (PANI) nanocomposite films after adding small amounts of auxiliary gases such as argon, nitrogen, and oxygen during atmospheric pressure (AP) plasma polymerization are investigated in detail. A separate gas-supply line for applying an auxiliary gas is added to the AP plasma polymerization system to avoid plasma instability due to the addition of auxiliary gas during polymerization. A small amount of neutral gas species in the plasma medium can reduce the reactivity of monomers hyperactivated by high plasma energy and prevent excessive crosslinking, thereby obtaining a uniform and regular PANI nanocomposite film. The addition of small amounts of argon or nitrogen during polymerization significantly improves the uniformity and regularity of PANI nanocomposite films, whereas the addition of oxygen weakens them. In particular, the PANI film synthesized by adding a small amount of nitrogen has the best initial electrical resistance and resistance changing behavior with time after the ex situ iodine (I2)-doping process compared with other auxiliary gases. In addition, it is experimentally demonstrated that the electrical conductivity of the ex situ I2-doped PANI film can be preserved for a long time by isolating it from the atmosphere.

Ultrafast Room Temperature Synthesis of Porous Polythiophene via Atmospheric Pressure Plasma Polymerization Technique and Its Application to NO2 Gas Sensors

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.

Transparent Polyaniline Thin Film Synthesized Using a Low-Voltage-Driven Atmospheric Pressure Plasma Reactor.

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.

In-Situ Iodine Doping Characteristics of Conductive Polyaniline Film Polymerized by Low-Voltage-Driven Atmospheric Pressure Plasma.

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.

Enhanced lithium electrochromic performance of tungsten oxide films by rapid co-synthesis of iron and tantalum oxides using cold atmospheric pressure plasma polymerization

Lithium electrochromic performance of organo-tungsten oxynitride (WOz1Cz2Nz3) films enhanced by additions of organo-iron oxynitride (FeOz1Cz2Nz3) or organo-tantalum oxynitride (TaOz1Cz2Nz3) with an atmospheric pressure plasma jet (APPJ) by a rapid deposition onto 60 Ω/square flexible polyethylene terephthalate (PET)/indium tin oxide (ITO) substrate at a short exposed duration of 54 s has been investigated. Flexible organo-tungsten-iron-tantalum oxynitride (WFexTayOz1Cz2Nz3) film possesses the significant Li+ ionic electrochromic performance, even though after being bent 360° around a 2.5-cm diameter rod for 1000 times and tested for 200 cycles of reversible Li+ ion intercalation and de-intercalation in a 1 M LiClO4-propylene carbonate electrolyte respectively by the potential sweep switching from the potential 2 V to − 1 V at a scan rate of − 40 mV/s and from the potential − 1 V to 2 V at a scan rate of 40 mV/s and by the potential step altering at the potential − 1 V for 20 s and the potential 2 V for 30 s, respectively. Li+ ionic intercalated charge of up to 13.2 mC/cm2 and optical modulation of up to 64.8% at a wavelength of 850 nm are proven for WFexTayOz1Cz2Nz3 film, respectively.

Fabrication of hydrogel coatings by atmospheric-pressure plasma polymerization: Function by structure and chemistry

Fabrication of hydrogel coatings by atmospheric-pressure plasma polymerization: Function by structure and chemistry