Determination of antioxidant activity of surface‐treated PET films coated with rosemary and clove extracts

Commercial PET films were surface treated and subsequently coated with either rosemary (RME) or clove (CE) extracts. Surface treatments involved (1) corona treatment, (2) chemical modification, and (3) plasma treatment. Radical scavenging activity (RSA) of both pure plant extracts and coated film extracts were determined using the 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) method. RME‐coated films showed a % RSA of 25.6%, 22.4%, and 24.1% for plasma, chemical modification, and corona treatment, respectively, at an extract concentration of 1402 ppm, respectively, while pure RME showed a %RSA of 16.0%. Respective %RSA values for CE were 25.0% for plasma, 25.2% for chemically modified, and 25.2% for corona‐treated films at 1402 ppm, while pure CE showed a %RSA of 47.6%. Thiobarbituric acid (TBA) test, performed on ground fish muscle wrapped in all types of employed films, showed a remarkable decrease in the degree of fish oxidation ranging between 50.0 and 80.0% after 6 days of storage. Contact angle measurements confirmed that surface chemically modified films had the highest adhesion strength followed by corona and plasma‐treated films. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X‐ray photoelectron spectroscopy (XPS) data also supported contact angle measurements. Finally, the oxygen permeability of surface‐treated films did not differ from untreated films indicating that surface treatment did not affect film barrier properties.     

Improved impermeability of PET substrates using oxygen and hydrogen plasma

A considerable decrease in permeability of polyethylene terephthalate (PET) films by means of surface plasma treatment in a reactive ion etching system is reported. The effects of oxygen and hydrogen radio frequency plasma on the surface properties of PET polymers are investigated by infrared spectroscopy, scanning electron microscopy (SEM), and X-ray photon spectroscopy (XPS). The surface morphology of the samples has been investigated using SEM and atomic force microscopy (AFM). The optical transmission spectroscopy has been studied further confirming the significant effect of O-plasma. Also the penetration of air through the treated substrates was investigated using a vacuum test. It is found that oxygen and hydrogen plasmas lead to about four-fold reduction in the penetration of air through the PET films, while the effect of hydrogen plasma has been more significant. In addition, oxygen plasma results in a rougher surface as observed both by AFM and SEM analyses. The formation of nanostructures on PET surfaces has been observed at plasma powers of 0.3 W/cm².     

Surface treatment of polycarbonate and polyethersulphone for SiNx thin film deposition

Silicon nitride thin films were deposited with good adhesion on plasma treated polyethersulphone (PES) and polycarbonate (PC) substrates by in-situ rf magnetron sputtering. The surfaces of the PES and PC substrates were performed by plasma treatment at various rf powers and processing time in Ar, O₂ atmosphere. From the X-ray Photoelectron Spectroscopy (XPS) examination of the surface of the treated substrates, it was found that the ratio of oxide containing bonds increased with increasing rf power. The surface roughness of the PES and PC substrates increased with increasing rf power. The plasma treated surface of the substrates became hydrophilic as measured by the water contact angle. The water contact angle for the PES and PC substrates decreased with increasing rf power and processing time, significantly. The lowest value of the contact angle of 14.09° was observed at rf power of 200 W. It was observed that the adhesion properties between the SiN_x films and substrates were enhanced by the plasma treatment.     

Blood compatibility of gas plasma-treated diamond-like carbon surface—Effect of physicochemical properties of DLC surface on blood compatibility

From the knowledge that zwitterion-type polymers show good blood compatibility, the introduction of both cationic and anionic functional groups onto diamond-like carbon (DLC) surface is expected to improve blood compatibility. Thus, DLC films were treated with oxygen and ammonia gas plasmas. The surfaces were characterized in terms of chemical composition by XPS, contact angle, and zeta potential. XPS analysis showed the introductions of a carboxyl group by oxygen plasma treatment and nitrogen atoms by ammonia plasma treatment. The evaluation of blood compatibility for the DLC surfaces was carried out in terms of platelets and the coagulation system. Excellent improvement of platelet compatibility was observed by the treatment with the gas plasmas, regardless of the plasma species. As for the compatibility with the coagulation system, DLC surfaces with a high concentration of carboxyl groups (COOH) markedly activated the system via the intrinsic pathway. However, the surfaces treated with ammonia plasma did not activate the system even though they had high COOH concentration. Measurement of the zeta potential revealed that the ammonia plasma treatment raised the potential from a negative value to a positive one. Though the introduction of amino groups to the surface was not detected directly, the treatment of ammonia plasma changed the electrical state of the DLC surface having COOH group, causing a difference in blood compatibility among the DLCs obtained by various plasma conditions.     

RF-Ar等离子体对聚乙烯薄膜的表面改性

采用射频辉光放电氩等离子体,在工作压力为20 Pa、功率为30W的条件下对低密度聚乙烯薄膜进行了不同时间的表面处理。借助静态接触角、X射线光电子能谱仪、原子力显微镜、差示扫描量热仪对薄膜改性前后的性能进行了表征及分析。研究结果表明:氩等离子体短时间(20 s)处理便可以有效改善薄膜表面的亲水性,处理时间大于20 s后接触角的变化并不明显;处理后的薄膜表面引入了大量的含氧及少量的含氮官能团;薄膜表面所形成的交联层阻挡了极性基团的翻转,有效延长了接触角的时效性;薄膜的表面形貌和结晶度发生了变化。     

电感耦合等离子体对HDPE粉体的表面处理

用搅拌式电感耦合等离子体反应器对高密度聚乙烯（HDPE）粉体进行表面处理,采用水接触角、红外光谱（FT-IR）和X射线光电子能谱（XPS）对等离子体处理前后HDPE粉体的水接触角、表面成分的变化进行分析。实验结果表明,随着等离子体处理时间延长和放电功率增加,水接触角减小。在功率100W处理30min后,水接触角从处理前...     

Enhanced printability of polyethylene through air plasma treatment

Low-density polyethylene (LDPE) foils were surface-modified by using non-thermal non-equilibrium oxidative air 40 kHz frequency, radiofrequency (RF) and microwave (MW) discharge plasma treatment. The pristine and treated specimens were morphologically and chemically characterised by Scanning Electron Microscopy (SEM) imaging, X-ray Photoelectron Spectroscopy (XPS) and contact angle measurement with surface energy evaluation. In addition, printability and ink adhesion tests were carried out on the samples, and quantitatively appraised by UV–VIS transmission spectroscopy. The overall outcome indicated chemical and physical changes after each treatment, and the improvement of printability. The present approach could serve as a viable and promising method to improve printability of polyethylene.     

丝素蛋白膜表面的等离子体磺酸化及体外抗凝血性能

从蚕丝中提取的丝素蛋白（Silk fibroin）制备成薄膜,首次采用二氧化硫等离子体处理在材料表现引入了磺酸基因;同时丝素蛋白膜用氨气等离子体处理后在表面接入氨基,利用1,3－丙磺酸内酯与氨基的反应在材料表面接枝磺酸。采用X光电子能谱和全反射红光谱分析材料的表面性质。材料的体外抗弟血性能由外凝血时间;凝血酶原时间（PT）、部分凝血活酶时间（APTT）和凝血酶时间（TT）作为评价标准。结果表明两种处理方法均能在丝素蛋白膜表面有效地接枝磺酸基因,而且材料的抗凝血性能有显著提高。     

Antimicrobial activity of glucose oxidase‐immobilized plasma‐activated polypropylene films

Antimicrobial enzyme, glucose oxidase (GOX), was covalently immobilized onto amino‐ and carboxyl‐plasma‐activated biorientated polypropylene films (BOPP) via glutaraldehyde and carbodiimide chemistries. N₂‐plasma + NH₃ and N₂‐plasma + CO₂ treatments were utilized to create amino (1.1 nmol/cm²) and carboxyl (0.9 nmol/cm²) groups densities onto the surface of BOPP films. GOX‐immobilized onto amino‐activated BOPP films using 2.5% glutaraldehyde produced higher enzymatic activities than GOX‐immobilized by 0.4% carbodiimide. Further immobilizations were carried out with glutaraldehyde as the coupling agent at temperatures of 4–75°C at pH 5.6 and 7.2. 10 s treatment was sufficient to immobilize GOX at high temperatures in both pH conditions, producing enzymatically active films which remained active over 30 days of storage. GOX covalently immobilized onto BOPP films completely inhibited the growth of Escherichia coli and substantially inhibited the growth of Bacillus subtilis; thus, they may have great potential to be exploited in various antimicrobial packaging film applications. Copyright © 2005 John Wiley & Sons, Ltd.     

Surface modifications of polymethylmetacrylate films using atmospheric pressure air dielectric barrier discharge plasma

In this paper, polymethylmetacrylate (PMMA) films are modified using an atmospheric pressure non-thermal plasma generated by a dielectric barrier discharge (DBD) in air. The DBD is generated in a plane-parallel reactor, which is driven by a μs pulse power supply with amplitude of up to 25 kV and repetition rate of 1 kHz, and the plasma generated shows homogeneous mode discharge characteristics verified by electrical measurements and light emission images with 0.5 ms exposure time. The treatment time ranging from 0 to 60 s and the discharge power density ranging from 11.62 to 30.83 W/m² are used to study the effects of discharge parameters on the surface treatment, and the surface properties of PMMA films are studied using contact angle and surface energy measurement, scanning electron microscopy (SEM), atomic force microscopy (AFM), fourier transformed infrared spectroscopy (FTIR) and x-ray photoelectron spectroscopy (XPS). The study shows that, after the plasma treatment, the surface of PMMA film is etched, and oxygen-containing polar groups are introduced into the surface. These two processes can induce a remarkable decrease in water contact and a remarkable increase in surface energy, and the surface properties of PMMA films is improved accordingly. It is shown that the improvement of hydrophobicity depends on the discharge power density and treatment time, and there is a saturation treatment time at each discharge power density. Increasing discharge power density can induce more effective treatment of PMMA films, and less treatment time is needed to achieve the same level of surface treatment by increasing the discharge power density. Because more oxygen-containing polar groups are created and more obvious etching is occurred on the PMMA surface at higher discharge power density.     

Effect of oxygen plasma treatment on bonding states for columnar structured a-CNx thin films prepared by reactive sputtering

Amorphous carbon nitride (a-CN) thin films were deposited on silicon single crystal substrates by rf-reactive sputtering method using a graphite target and nitrogen gas. The substrate temperature was varied from room temperature (RT) to 853 K. After deposition, the effect of oxygen plasma treatment on bonding structures of the film surface has been studied by using an oxygen discharge at 16 Pa and rf power of 85 W. The chemical bonding states and film composition were analyzed by X-ray photoelectron spectroscopy (XPS), while film thickness was obtained from scanning electron microscopy (SEM) and ellipsometer. XPS study revealed that the films have NO₂ and NO₃ bonding structures when the films are deposited at temperatures higher than 673 K. After exposure to oxygen plasma, carbon in the film surface was etched selectively and this phenomenon was observed in all films. In contrast, the surface concentration of nitrogen was ket at constant values before and after oxygen plasma treatment. The NO₃ bonding state had dramatically increased after oxygen plasma treatment for films deposited at higher deposition temperatures. The film surfaces have been observed to change the function from hydrophobic to hydrophilic after oxygen plasma treatment.     

Structural and surface energy analysis of nitrogenated ta-C films

Surface and bulk properties of the Filtered Cathodic Vacuum Arc prepared nitrogenated tetrahedral amorphous carbon (ta-C:N) films were characterized by X-ray Photoelectron Spectroscopy (XPS), Time of Flight Secondary Ion Mass Spectroscopy (ToF-SIMS), Raman spectroscopy, Atomic Force microscopy and contact angle techniques. An increase in the Nitrogen (N) content of the films is accompanied by a reduction in the sp³ fraction, confirmed via the deconvolution of the C 1 s XPS spectra. Critical Raman parameters such as peak position and peak width of the G band, defect ratio, I_D/I_G and skewness of the G line were analyzed as a function of N content. ToF-SIMS showed the variance of chemical composition with the increase in the sputtering depth. While some amount of incorporated oxygen and hydrogen were observed for all films; for high N content ta-C:N films signature of CN bonds was evident. Surface energies (both polar and dispersive components) for these ta-C:N films were analyzed in a geometric mean approach. Contact angle measurements using both deionized water and ethylene glycol reveal that upon the insertion of nitrogen into ta-C films, the initial change in the contact angle is sharp, followed by a gradual decrease with subsequent increase in N content. The variation of contact angle with increasing N content corresponds to an increase of the total surface energy with an increase of the polar component and a decrease of the dispersive component.     

Effect of hydrogen plasma treatment on the surface morphology, microstructure and electronic transport properties of nc-Si:H

Hydrogenated nanocrystalline silicon (nc-Si:H) films, deposited by reactive radio-frequency sputtering with 33% hydrogen dilution in argon at 200 °C, were treated with low-power hydrogen plasma at room temperature at various power densities (0.1-0.5 W/cm²) and durations (10 s-10 min). Plasma treatment reduced the surface root mean square roughness and increased the average grain size. This was attributed to the mass transport of Si atoms on the surface by surface and grain boundary diffusion. Plasma treatment under low power density (0.1 W/cm²) for short duration (10 s) caused a significant enhancement of crystalline volume fraction and electrical conductivity, compared to as-deposited film. While higher power (0.5 W/cm²) hydrogen plasma treatment for longer durations (up to 10 min) caused moderate improvement in crystalline fraction and electrical properties; however, the magnitude of improvement is not significant compared to low-power (0.1 W/cm²)/short-duration (10 s) plasma exposure. The results indicate that low-power hydrogen plasma treatment at room temperature can be an effective tool to improve the structural and electrical properties of nc-Si:H.     

Structural changes of a pyrolytic graphite surface oxidized by electrochemical and plasma treatment

Pyrolytic graphite (PG) surfaces have been oxidized by electrochemical and oxygen plasma treatment. The oxidized PG surfaces have been studied by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared attenuated total reflection spectroscopy (FT-IR-ATR). Oxidation caused by the plasma treatment results in a small increment of the oxygen: carbon (O/C) ratio, compared to electrochemical treatment. Moreover, the increment of the O/C ratio for the plasma treated edge surface is smaller than that for the plasma treated basal surface. A steep gradient in oxygen concentration exists within the edge subsurface of PG for samples subjected to severe electrochemical treatment, as compared to those samples subjected to plasma treatment. For the electrochemical treatment, carbonyl, carboxyl, ester and lactone groups are introduced to the edge surface following relatively severe treatment. The ratio of ester and lactone groups to carboxyl groups increases with the extent of electrochemical treatment. For plasma treated samples, other types of oxygen-containing groups, which are probably keto-enol groups, are added to the edge surface, unlike during electrochemical treatment.     

Plasma enhanced chemical vapor deposition of low dielectric constant SiOC(-H) films using MTES/O2 precursor

Low dielectric constant SiOC(-H) thin films were deposited by plasma enhanced chemical vapor deposition (PECVD) using methyltriethoxysilane (MTES) and oxygen as precursors. The SiOC(-H) films were prepared with MTES/O₂ flow rate ratio of 80%, rf power of 700 W and the working pressure was varied from 110 to 150 mTorr. Then the films were annealed at different temperatures in an Ar ambient for 30 min in order to study their thermal stability. Film thickness and refractive index were measured by SEM and ellipsometry, respectively. Bonding characteristics of the films were investigated by Fourier transform infrared (FTIR) spectroscopy. The dielectric constant of SiOC(-H) film was evaluated by C-V measurements using Al/SiOC(-H)/p-Si structure. The dielectric constants as low as 2.4 have been obtained for the film annealed at 500 °C with the working pressure of 150 mTorr. The annealing treatment was found to reduce dielectric constant significantly due to abundant incorporation of methyl group into the Si-O network. These results demonstrated the promising characteristics of SiOC(-H) thin films deposited by using oxygen and MTES precursor.     

Surface texture modification of spin-coated SiO2 xerogel thin films by TMCS silylation

The SiO₂ xerogel thin films were deposited successfully by sol?Cgel technique via the acid-catalyzed hydrolysis and condensation of tetraethylorthosilicate (TEOS) with ethanol as a solvent. Further, the deposited thin films were treated wet chemically by trimethylchlorosilane (TMCS) and hexane solution with 10% and 15% volume ratio to remove the hydroxyl groups from the surface of deposited SiO₂ thin films. These as deposited and surface-modified films were characterized by ellipsometer, Fourier transform infrared (FTIR) spectrometer and contact angle meter. The presence of 2900 and 850?cm^?1 peaks of CH₃ vibrations in FTIR spectra of surface-modified films confirms the hydrphobisation of SiO₂ surface. The maximum contact angle of 108·7° was observed for the surface-modified film at 10% TMCS.     

Surface Modification of Electrospun Polycaprolactone Nanofiber Meshes by Plasma Treatment to Enhance Biological Performance

A critical aspect in the development of biomaterials is the optimization of their surface properties to achieve an adequate cell response. In the present work, electrospun polycaprolactone nanofiber meshes (NFMs) are treated by radio‐frequency (RF) plasma using different gases (Ar or O₂), power (20 or 30 W), and exposure time (5 or 10 min). Morphological and roughness analysis show topographical changes on the plasma‐treated NFMs. X‐ray photoelectron spectroscopy (XPS) results indicate an increment of the oxygen‐containing groups, mainly ? OH and ? C?O, at the plasma‐treated surfaces. Accordingly, the glycerol contact angle results demonstrate a decrease in the hydrophobicity of plasma‐treated meshes, particularly in the O₂‐treated ones. Three model cell lines (fibroblasts, chondrocytes, and osteoblasts) are used to study the effect of plasma treatments over the morphology, cell adhesion, and proliferation. A plasma treatment with O₂ and one with Ar are found to be the most successful for all the studied cell types. The influence of hydrophilicity and roughness of those NFMs on their biological performance is discussed. Despite the often claimed morphological similarity of NFMs to natural extracellular matrixes, their surface properties contribute substantially to the cellular performance and therefore those should be optimized.     

XPS study of oxygen plasma activated PET

A study on oxygen plasma functionalization of polyethyleneterephthalate (PET) is presented. Samples were exposed to a weakly ionized, highly dissociated RF oxygen plasma with an electron temperature of 5 eV, a density of positive ions of 8×10¹⁵ m⁻³ and a density of neutral oxygen atoms of 4×10²¹ m⁻³. The oxygen pressure was 75 Pa and the discharge power was 200 W. The wettability of plasma-modified samples was determined by measuring the contact angle of a water drop, while the appearance of the functional groups on the sample surface was determined by using a high-resolution X-ray photoelectron spectrometer (XPS). Already in the order of seconds of the plasma treatment the samples were covered by the surface functional groups. These results were explained by the high flux of oxygen atoms onto the sample surface. The stability of functional groups on the plasma-modified PET surface stored in a dry plastic box was monitored by using XPS as a function of the ageing time. After 1 day of ageing, the concentration of newly formed functional groups decreased by about 15%.     

氩气低温等离子体处理HDPE薄膜表面的性能研究

利用低温等离子体,以氩气为工作气体,在工作压强为20Pa、处理功率为30W的条件下对HDPE薄膜进行了表面改性。用接触角、SEM、AFM、XPS等手段对改性结果进行了分析和表征。研究结果表明:在0～300s的处理时间内,失重率在处理时间为90s左右时达最大值;接触角在0～160s内随处理时间的增加显著减小,而在160～300s的处理时间内没有发生明显变化;改性后的接触角随着放置时间的推移出现微弱回复;HDPE薄膜经过氩气低温等离子体处理后,能在其表面形成各种极性基团,主要是羰基、羟基和羧基,且薄膜经处理后,其表面的结合能及平面光洁度发生了改变。     

Increasing mouse embryonic fibroblast cells adhesion on superhydrophilic vertically aligned carbon nanotube films

We have analyzed the adhesion of mouse embryonic fibroblasts (MEFs) genetically modified by green fluorescence protein (GFP) gene cultured on vertically-aligned carbon nanotubes (VACNTs) after 6 days. The VACNTs films grown on Ti were obtained by microwave plasma chemical vapor deposition process using Fe catalyst and submitted to an oxygen plasma treatment, for 2 min, at 400 V and 80 mTorr, to convert them to superhydrophilic. Cellular adhesion and morphology were analyzed by scanning electron, fluorescence microscopy, and thermodynamics analysis. Characterizations of superhydrophilic VACNTs films were evaluated by contact angle and X-Ray Photoelectron Spectroscopy. Differences of crowd adhered cells, as well as their spreading on superhydrophilic VACNTs scaffolds, were evaluated using focal adhesion analysis. This study was the first to demonstrate, in real time, that the wettability of VACNTs scaffolds might have enhanced and differential adherence patterns to the MEF-GFP on VACNTs substrates.