Surface modification of aromatic polyamide film by remote oxygen plasma

Surface modification of poly(p-phenylene terephthalamide) (PPTA) film by a remote oxygen plasma treatment has been investigated from a viewpoint of comparison with a direct oxygen plasma treatment. We call the modification procedure in a space far away from the oxygen plasma zone “the remote oxygen plasma treatment,” and the modification procedure in a space just in the oxygen plasma zone (a conventional oxygen plasma treatment) “the direct oxygen plasma treatment.” In a space far away from the plasma zone, oxygen radicals rather than electrons and oxygen ions are predominant, and the PPTA film can be modified by the remote oxygen plasma treatment into a hydrophilic surface without heavy degradation of the PPTA film. The PPTA film surfaces modified by the remote oxygen plasma treatment were analyzed with contact angle measurement, scanning microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 831–840, 1997     

Comparative studies on surface modification of poly(ethylene terephthalate) by remote and direct argon plasmas

Surface modification of poly(ethylene terephthalate) (PET) film by an argon (Ar) plasma was investigated as a function of the distance from the Ar plasma zone. Changes in distance between the PET film and the Ar plasma zone had a strong influence on the surface modification of the film. The direct Ar plasma treatment (distance between the PET film and Ar plasma zone = 0 cm) was effective in hydrophilic surface modification, but heavy etching reactions occurred during the modification. On the other hand, the remote Ar plasma treatment (distance between the PET film and Ar plasma zone = 80 cm) modified the PET film surfaces to be hydrophilic without heavy etching reactions, although the hydrophilicity of the PET was lower than that by the direct Ar plasma. The remote Ar plasma treatment was distinguished from the direct Ar plasma treatment from the viewpoint of degradation reactions. The remote Ar plasma treatment rather than the direct Ar plasma treatment was an adequate procedure for surface modification and caused less polymer degradation on the film surface. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 808–815, 2001     

Long‐term stable hydrophilic surface modification of poly(ether ether ketone) via the multilayered chemical grafting method

The aging phenomena of a poly(ether ether keton) (PEEK) surface hydrophilically modified via various protocols was investigated. The use of plasma treatment or chemical etching methods offers a relatively convenient surface modification route. However, the effects of hydrophilic treatment quickly disappeared and its original surface property was recovered within a few hours or a few days when stored at ambient conditions. Surface treatment based on a single‐layered chemical grafting method rendered an excellent hydrophilic surface with an initial contact angle of <15° and an improved retardation of surface aging. However, the contact angle of the modified PEEK specimen gradually increased with time and eventually reached ～50° after 23 days. A new method for the long‐term stable hydrophilic surface treatment of PEEK using a multilayered chemical grafting strategy was also developed. With this regard, aging of the modified surface could be significantly retarded over ～90 days. It was believed that the effectiveness of the surface modification and the retarded aging phenomena via the multilayered hydrophilic treatment could be attributed to mechanical and chemical stability of the covalently bonded active surface groups on the grafted polymer networks. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46042.     

Effect of dihydroxydiphenyl ether on poly(ether ether ketone)

A series of modified poly(ether ether ketone) (PEEK) polymers were synthesized by introduction of addition ether groups from dihydroxydiphenyl ether (DHDE) into the PEEK structure. The inherent viscosity of the DHDE-modified PEEK increased with reaction time at 320 °C. DSC thermograms showed the melting points of the obtained PEEK decreased with the increase of the DHDE content in the backbone. The degradation temperature (T_d) was slightly decreased by the introduction of DHDE. The crystallinity as measured via the X-ray diffraction (XRD) increases with the introduction of DHDE into the modified PEEK. The crystalline structure was identified as an orthorhombic structure with lattice constants a = 7.72 Å, b = 5.86 Å, and c = 10.24 Å. Due to the glass transition temperature (T_g) and the melting temperature (T_m) decreasing with the increase of the DHDE content in the reaction system. the processability of the resultant PEEK could be improved through this DHDE modification.     

Surface modification of polyethylene powder using plasma reactor with fluidized bed

The fluidization technique was applied for the surface modification of powder by plasma, and whether the technique was a practically useful one in the surface modification of powder or not was discussed. Polyethylene powder was used as a specimen to be modified. The oxygen plasma treatment of the polyethylene powder in the fluidized state showed a capability that the surface of the powder was changed from hydrophobic to hydrophilic. The contact angle of water for the treated powder surface was 51°C, which was estimated from the dynamic wicking data. The hydrophilic surface modification of the polyethylene powders in the fluidized bed required the operation of the plasma treatment for at least 3 h. The requirement of the plasma operation for long time rises mainly from large surface area of the powder. The oxygen plasma treatment led to the formation of oxygen functionalities including C ? O and C(O)? O? groups at the outermost layer of the powder. The concentration of the C?O and C(O)? O? functionalities reached 10 and 6% of the total carbon elements being in the XPS sampling depth, respectively. From these results we conclude that the fluidization technique is a useful manner in the surface modification of powder by plasma.     

Intermolecular interaction and conformation in poly(ether ether ketone)/poly(ether imide) blends — An infrared spectroscopic investigation

The intermolecular interaction and the conformation in miscible blends of poly(ether ether ketone) (PEEK) and poly(ether imide) (PEI) have been investigated by Fourier-transform infrared (FTIR) spectroscopy. The intensity of the C=O out-of-phase stretching (1725 cm^–1) of PEI shows a minimum at 70 wt% PEI, whereas that of the C=O in-phase stretching (1778 cm^–1) is not perturbed by blending. These intensity variations have been attributed to the effect of blending on the coplanarity of the two imide rings bridged by the phenylene group. Change in coplanarity of these two imide rings alters the intensity of the C=O out-of-phase stretching, but it can not affect the intensity of the C=O in-phase stretching. When the two imide rings are perpendicular to each other, the intensity of the C=O out-of-phase stretching is shown to reach the minimum, corresponding to the observation at 70 wt% PEI. The difference spectra (blend - PEEK - PEI) reveal that the bands associated with the diphenyl ether groups in PEEK are modified by blending with PEI. It is proposed that the favorable interaction takes place between the oxygen lone-pair electrons of the ether group in PEEK and the electron-deficient imide rings in PEI.     

Oxygen plasma modification of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) film surfaces for tissue engineering purposes

Plasma glow‐discharge application is known as a technique to coat or modify the surfaces of various materials. In this study, the influence of oxygen rf‐plasma treatment on surface and bulk properties of a biological polyester, poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate), were studied by determining water content and water contact angle, and by using X‐ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The plasma‐treated films absorbed more water than the untreated film, and the absorbance increased with the total power applied. The water contact angles decreased and O/C atomic ratio increased on treatment, indicating that the material became more hydrophilic due to increases in the oxygen‐containing functional groups on the surface of the polymer. A direct relation could be observed when the O/C ratio was plotted against the total power applied (treatment duration × treatment power). SEM revealed a visual record of surface modification, the extent of which increased with increased total power. It was thus possible to alter the surface chemistry and relevant properties of the polymer film using oxygen plasma as a tool. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1285–1289, 2003     

Surface modification of thermotropic poly(oxybenzoate‐co‐oxynaphthoate) copolyester by remote oxygen plasma for copper metalization

Poly(oxybenzoate‐co‐oxynaphthoate) (POCO) film surfaces were modified with remote oxygen plasma, and the effects of the modification on the adhesion between the copper layer and POCO were investigated. The remote‐oxygen‐plasma treatment led to a noticeable decrease in the contact angle, which was mainly due to the C? O functional groups on the surface. The modification of the POCO surface by remote oxygen plasma was effective in improving the adhesion with copper metal. The peel strength for the copper metal/POCO system was enhanced from 10 to 127.5 mN/5 mm by the surface modification. The failure mode of the copper metal/POCO system was an interface layer between the oxidized micro‐POCO fibril surface and the copper metal layer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2400–2408, 2003     

低温等离子体处理及丙烯酸接枝改性膨化聚四氟乙烯薄膜

采用He等离子体对膨化聚四氟乙烯(ePTFE)薄膜进行表面亲水处理,并引发接枝丙烯酸单体实现持久亲水改性.实验探究了不同等离子处理工艺和接枝工艺对ePTFE薄膜亲水性能的影响,并利用接触角、X光电子能谱(XPS)进行表征.研究结果表明,等离子体预处理后,ePTFE薄膜表面的接触角由145°降至102°;再接枝丙烯酸单体...     

XPS study of the PET film surface modified by CO2 plasma: effects of the plasma parameters and ageing

Chemical modification of the PET surface by carbon dioxide plasma treatment has been studied using X-ray photoelectron spectroscopy (XPS). The plasma process results mainly in the formation of carbonyl, carboxyl, and carbonate groups at the PET surface. Under rather mild treatment conditions (low plasma power combined with a short treatment time), the formation of C-O bonds was found to be dominant, whereas the formation of highly oxidized carbon or double-bonded oxygen-containing groups required a high plasma power or a relatively long treatment time. The treatments performed under excessive conditions frequently led to degradation at the polymer surface. Angle-resolved XPS analyses performed on a freshly modified PET film showed a slight decrease in the O/C atomic ratio when the take-off angle (TOA) increased, indicating a relatively uniform distribution of oxygen within the sampling depth (estimated to be about 8 nm at 80° TOA). The chemical composition of the plasma-modified surface was found to be relatively stable on extended storage in air under ambient conditions. The decrease in oxygen-containing groups at the carbon dioxide-plasma-treated PET surface upon ageing is mainly ascribed to the surface rearrangement of macromolecular segments, the loss of oxygen-containing moieties introduced by the plasma treatment, and the possible migration of non-affected PET chains from the bulk to the surface region.     

Surface functionalization without lattice degradation of highly crystalline nanoscaled carbon materials using a carbon monoxide atmospheric plasma treatment

Atmospheric plasma treatments on various forms of carbon were performed to compare the effect of surface modification using carbon monoxide (CO) as the active gas, in comparison to the conventionally used O₂. Changes in surface characteristics were analyzed using X-ray photoelectron spectroscopy (XPS) as a function of duration. The results indicated that use of O₂ plasma resulted in only a limited oxygen uptake (O/C = 0.11), while CO treatments resulted in tailorable surface O/C ratios as high as 0.69, a result not attainable when using low-pressure RF plasmas (O/C < 0.1). High-resolution XPS analysis and Auger spectroscopy confirmed that a tailorable level of carbonyl functional groups could be evenly distributed throughout the surface. Both Raman and scanning tunneling microscopy (STM) indicated nano-scale degradation of the structure when using the O₂ treatment. On the other hand, CO treated specimens exhibited no observable damage to the material with high levels of oxygen incorporation. Contact angle measurements verified the formation of a highly stable hydrophilic surface and excellent dispersion was observed in an aqueous solution on treated specimens after CO treatment. The CO treatment was also successfully applied to SWCNT with similar results and no degradation of structure.     

聚醚醚酮表面壳聚糖的固定

通过紫外光接枝和湿化学法连用在聚醚醚酮 （PEEK）表面固定上具有抑菌杀菌作用的壳聚糖。结果表明,相比未改性的PEEK表面,改性后材料表面亲水性提高;通过扫描电子显微镜和X射线光电子能谱分析证明壳聚糖成功接枝在了PEEK薄膜表面;随着壳聚糖浓度的提高,材料表面的壳聚糖接枝率增加。     

Plasma‐induced surface modification and adhesion enhancement of polypropylene surface

Unoriented (UPP) and biaxially oriented (BOPP) polypropylene films were treated under radio frequency plasma of air, nitrogen, oxygen, and ammonia. Surface modification of polypropylene films was investigated by using surface energy measurement and attenuated total reflection (ATR)‐FTIR spectroscopy. Surface energy of air and nitrogen plasma‐treated polypropylene film increased for shorter treatment time and then decreased and attained an equilibrium value. Such changes in surface energy were not observed for oxygen and ammonia plasma‐treated polypropylene film, which increased to an equilibrium value. ATR‐FTIR studies revealed characteristic differences in the absorption spectra for short‐duration and long‐duration treatments. From the relative intensity change in the C—H stretching vibration, the mechanism of surface chemical reaction could be inferred. Studies regarding the durability of surface modification due to plasma treatment were evaluated by investigating surface energy of samples aged for 2 months. Treated films subjected to peel strength measurement showed improvement in bondability for UPP and BOPP film by hydrophilic surface modification accompanied by surface crosslinking. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 925–936, 2002     

Surface modification and degradation of poly(lactic acid) films by Ar-plasma

Surface modification of poly(lactic acid) (PLA) film surface by Ar-plasma was investigated by contact angle measurements and XPS in order to answer the following two questions. (1) Could the Ar-plasma modify the PLA film surfaces? (2) What chemical reactions occurred on the film surfaces during the Ar-plasma treatment? The Ar-plasma treatment did not lead to hydrophilic modification of the PLA film surface, but to degradation reactions of the PLA film. Poor modification may be due to instability of the carbon radicals formed from C—O bond scission in the PLA chains by the Ar-plasma.     

Surface modification of aromatic polyamide film by aminoethanethiol solution for silicon rubber composites

The surface modification of poly(p-phenylene terephthalamide) (PPTA) film with 2-aminoethanethiol (AET) to adhere to silicon rubber was investigated. The combination of the AET treatment and the silane coupling treatment is an effective surface modification of the PPTA film for this adhesion. The x-ray photoelectron spectroscopy (XPS) analyses show that the AET treatment does not generate sulfur functionalities at the surface of the PPTA film but does generate oxygen functionalities. In the AET treatment process, a part of the amide groups near the surface of the PPTA film is hydrolyzed to form carboxylic acid groups and amino groups. The oxygen functionalities are condensed at the film surface, and nitrogen functionality is diluted at the film surface. The C(O)O moiety at the PPTA film surface may be a key factor for the adhesion with silicon rubber. The C(O)O moiety is mobile from the bulk of the PPTA film to the film surface. Hot water treatment of the original PPTA film makes the impossible adhesion with the silicon rubber possible. The hot water treatment, however, is not as powerful a surface modification as the AET treatment. © 1995 John Wiley & Sons, Inc.     

A comparison of gas-phase methods of modifying polymer surfaces

Oxidation is the most common surface modification of polymers. This paper presents a comparison of five gas-phase surface oxidation processes: corona discharge, flame, remote air plasma, ozone, and combined UV/ozone treatments. Well-characterized biaxially oriented films of polypropylene and poly(ethylene terephthalate) were treated by each of the five techniques. The surface-treated films were then analyzed by X-ray photoelectron spectroscopy (XPS or ESCA), contact-angle measurements, and Fourier-transform IR (FTIR) spectroscopy. Corona, flame, and remote-plasma processes rapidly oxidize polymer surfaces, attaining XPS O/C atomic ratios on polypropylene of greater than 0.10 in less than 0.5 s. In contrast, the various UV/ozone treatments require orders of magnitude greater exposure time to reach the same levels of surface oxidation. While corona treatment and flame treatment are well known as efficient means of oxidizing polymer surfaces, the ability of plasma treatments to rapidly oxidize polymers is not as widely appreciated. Of the treatments studied, flame treatment appears to be the 'shallowest'; that is, the oxygen incorporated by the treatment is most concentrated near the outer surface of the film. Corona and plasma treatments appear to penetrate somewhat deeper into the polymers. At the other extreme, the UV/ozone treatments reach farther into the bulk of the polymers.     

Action of transfer film in improving friction and wear behaviors of iron‐ and copper‐filled poly(ether ether ketone) composites

The composites of poly(ether ether ketone) (PEEK) filled with micrometer‐sized Cu and Fe particles were prepared by compression molding. The friction and wear behaviors of the composites were examined on a pin‐on‐disc friction‐and‐wear tester by sliding PEEK‐based composites against tool steel at a sliding speed of 1.0 m s⁻¹ and a normal load of 19.6N. Optical microscopic analysis of the transfer film and of the worn pin surfaces and wear debris was performed to investigate the wear mechanisms of the composites. It was found that Cu and Fe used as filler considerably decreased the wear rate of PEEK. A thin, uniform, and tenacious transfer film was formed when Cu was used as the filler, and a nonuniform and thick transfer film was formed when Fe was used as the filler. The transfer film played a key role in increasing the wear resistance of the PEEK composites. Plastic deformation was dominant for wear of PEEK–Cu, while abrasion and adhesion were dominant for wear of PEEK–Fe. Because of the strong affinity between Fe as filler and its identical counterpart in the counterface tool steel surface, the adhesion between the PEEK–Fe composite surface and the counterface tool steel surface was thus severe. This contributed to the generation of a thicker transfer film for PEEK–Fe. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 179–184, 2000     

Functionalized poly(ether ether ketone): Improved mechanical property and acellular bioactivity

Poly(ether ether ketone), PEEK, was functionalized by addition of pendant functional groups, that is, acetyl, carboxylic, acyl chloride, amide, and amine groups in the benzene ring of polymer backbone without substituting the parent (ether or ketonic) functional groups of polymer to improve the mechanical and surface adhesivity with acellular inorganic biomaterials. The functional groups of virgin PEEK and functionalized PEEK were identified by Fourier transform infrared spectroscopy and ¹³C nuclear magnetic resonance. The crystallinity was studied by X‐ray diffraction and further supported by differential scanning calorimetry (DSC) analysis. Similarly, the change in glass transition temperature was confirmed by the DSC and dynamic mechanical analysis (DMA). The improved mechanical property was also evaluated by DMA. The excellent surface adhesivity and bioactivity were revealed by acellular in vitro test using simulated body fluid. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Plasma surface modification of polyethylene: short-term vs. long-term plasma treatment

A remote plasma reactor, with air as the plasma gas, has been used for in-line surface modification of linear low-density polyethylene tape (LLDPE) passing 10 cm below the main plasma zone. Line speeds of up to 0.70 m/s were tested, allowing the study of 0.014 s exposure times to the plasma. Oxygen to carbon (O/C) ratios averaging 0.11 were observed on a reproducible basis. The reactor was also used for static plasma treatment under similar experiment onditions. This allowed a comparative study of short-term (milliseconds) vs. long-term (several seconds) plasma treatment. High-resolution X-ray photoelectron spectroscopy (XPS) analysis of the treated polymer surface suggested the formation of hydroxyl (C-OH), carbonyl (C=O) and carboxyl (O-C=O) groups, even after short plasma treatment. The intensities of these components were seen to increase in approximately equal quantities with increasing O/C ratio. Water washing of polyethylene surfaces with high O/C ratios showed a loss of oxygen, apparent as a decrease in O-C=O groups in the C 1s spectra. A smaller loss in oxygen was observed when washing samples that had been plasma-treated for milliseconds. A surface ageing study revealed that polyethylene surfaces that had been plasma-treated for short time periods showed only a negligible loss of oxygen on prolonged exposure to air. Surfaces treated for longer time periods showed a loss of up to 50% of the total oxygen on the surface within a few days of treatment. Static secondary ion mass spectrometry has provided some supporting evidence for surface damage of the treated films.     

Plasma treatment of PET and acrylic coating surfaces - I. In-situ XPS measurements

The surface modification of poly(ethylene terephthalate) (PET) and UV-cured tripropyleneglycol diacrylate (acrylic) films induced by remote N₂ and Ar microwave plasmas (2.45 GHz) was compared by in-situ XPS measurements. Both N₂ and Ar plasma treatments led to destruction of the initial oxygen-containing groups. The destruction of ester groups was much faster for the acrylic than for the PET film, and the destruction of ether groups was much faster than that of ester groups within the acrylic film. Among the plasma gases, N₂ was more effective than Ar in the case of PET, but their difference was negligible in the case of the acrylic film. The higher stability of the PET surface was attributed to the presence of a rigid aromatic backbone, which protected the ester groups from plasma UV irradiation and stabilized the free radicals. The lower stability of the acrylic film was associated with the presence of weak ether groups. New functional groups were created, attributed to carbonyl in the case of Ar, and carbonyl/amide and amine in the case of N₂ plasma treatments. The formation of these new functional groups was very small compared with the loss of ether and ester groups, suggesting that the destruction of these oxygen-containing groups proceeded mainly through elimination of the entire groups.