Research

8 pages, 1377 KiB

Open AccessArticle

Bulk Polymerization of Acrylic Acid Using Dielectric-Barrier Discharge Plasma in a Mesoporous Material

by Matthew Mieles, Sky Harper and Hai-Feng Ji

Polymers 2023, 15(13), 2965; https://doi.org/10.3390/polym15132965 - 06 Jul 2023

Viewed by 1846

This research investigated a non-thermal, dielectric-barrier discharge (DBD) plasma-based approach to prepare poly(acrylic acid) (PAA) from acrylic acid in its liquid state at atmospheric temperature and pressure. Neither additives nor solvents were needed, and the polymerization was accomplished both as a film and [...] Read more.

This research investigated a non-thermal, dielectric-barrier discharge (DBD) plasma-based approach to prepare poly(acrylic acid) (PAA) from acrylic acid in its liquid state at atmospheric temperature and pressure. Neither additives nor solvents were needed, and the polymerization was accomplished both as a film and inside a sheet of mesoporous paper. All prepared samples were characterized and the DBD plasma-initiated kinetics were analyzed for the polymerization of acrylic acid. Using FTIR semi-quantitative analysis, the degree of polymerization was monitored, and the reaction followed an overall second-order kinetic model with respect to the DBD-initiated polymerization. Additionally, the application of a PAA-modified paper as a water retention cloth or ‘wet wipe’ was investigated. The results showed that the PAA-modified paper substrates using DBD plasma increased water retention as a function of plasma treatment time. Full article

(This article belongs to the Special Issue Plasma Processing of Polymers)

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15 pages, 3719 KiB

Open AccessArticle

Adhesion Properties and Stability of Non-Polar Polymers Treated by Air Atmospheric-Pressure Plasma

by Emma Bîrleanu, Ilarion Mihăilă, Ionuț Topală, Cătălin Borcia and Gabriela Borcia

Polymers 2023, 15(11), 2443; https://doi.org/10.3390/polym15112443 - 25 May 2023

Cited by 3 | Viewed by 1116

Abstract

Atmospheric-pressure plasma (APP) has advantages for enhancing the adhesion of polymers and has to provide uniform, efficient treatment, which also limits the recovery effect of treated surfaces. This study investigates the effects of APP treatment on polymers that have no oxygen bonded in [...] Read more.

Atmospheric-pressure plasma (APP) has advantages for enhancing the adhesion of polymers and has to provide uniform, efficient treatment, which also limits the recovery effect of treated surfaces. This study investigates the effects of APP treatment on polymers that have no oxygen bonded in their structure and varying crystallinity, aiming to assess the maximum level of modification and the post-treatment stability of non-polar polymers based on their initial structure parameters, including the crystalline–amorphous structure. An APP reactor simulating continuous processing operating in air is employed, and the polymers are analyzed using contact angle measurement, XPS, AFM, and XRD. APP treatment significantly enhances the hydrophilic character of the polymers, with semicrystalline polymers exhibiting adhesion work values of approximately 105 mJ/m² and 110 mJ/m² for 0.5 s and 1.0 s exposure, respectively, while amorphous polymers reach approximately 128 mJ/m². The maximum average oxygen uptake is around 30%. Short treatment times induce the roughening of the semicrystalline polymer surfaces, while the amorphous polymer surfaces become smoother. The polymers exhibit a limit to their modification level, with 0.5 s exposure being optimal for significant surface property changes. The treated surfaces remain remarkably stable, with the contact angle only reverting by a few degrees toward that of the untreated state. Full article

(This article belongs to the Special Issue Plasma Processing of Polymers)

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16 pages, 6657 KiB

Open AccessArticle

Iron-Oxide-Nanoparticles-Doped Polyaniline Composite Thin Films

by Bogdan Butoi, Carmen Steluta Ciobanu, Simona Liliana Iconaru, Constantin Cătălin Negrilă, Madalina Andreea Badea, Mihaela Balas, Anca Dinischiotu, Gabriel Predoi, Bogdan Bita, Andreea Groza and Daniela Predoi

Polymers 2022, 14(9), 1821; https://doi.org/10.3390/polym14091821 - 29 Apr 2022

Cited by 5 | Viewed by 2165

Abstract

Iron-oxide-doped polyaniline (PANI-IO) thin films were obtained by the polymerization of aniline monomers and iron oxide solutions in direct current glow discharge plasma in the absence of a buffer gas for the first time. The PANI-IO thin films were deposited on optical polished [...] Read more.

Iron-oxide-doped polyaniline (PANI-IO) thin films were obtained by the polymerization of aniline monomers and iron oxide solutions in direct current glow discharge plasma in the absence of a buffer gas for the first time. The PANI-IO thin films were deposited on optical polished Si wafers in order to study surface morphology and evaluate their in vitro biocompatibility. The characterization of the coatings was accomplished using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), metallographic microscopy (MM), and X-ray photoelectron spectroscopy (XPS). In vitro biocompatibility assessments were also conducted on the PANI-IO thin films. It was observed that a uniform distribution of iron oxide particles inside the PANI layers was obtained. The constituent elements of the coatings were uniformly distributed. The Fe-O bonds were associated with magnetite in the XPS studies. The surface morphology of the PANI-IO thin films was assessed by atomic force microscopy (AFM). The AFM topographies revealed that PANI-IO exhibited the morphology of a uniformly distributed and continuous layer. The viability of Caco-2 cells cultured on the Si substrate and PANI-IO coating was not significantly modified compared to control cells. Moreover, after 24 h of incubation, we observed no increase in LDH activity in media in comparison to the control. In addition, our results revealed that the NO levels for the Si substrate and PANI-IO coating were similar to those found in the control sample. Full article

(This article belongs to the Special Issue Plasma Processing of Polymers)

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15 pages, 4834 KiB

Open AccessArticle

Chemistry-Induced Effects on Cell Behavior upon Plasma Treatment of pNIPAAM

by Veronica Satulu, Valentina Dinca, Mihaela Bacalum, Cosmin Mustaciosu, Bogdana Mitu and Gheorghe Dinescu

Polymers 2022, 14(6), 1081; https://doi.org/10.3390/polym14061081 - 08 Mar 2022

Cited by 1 | Viewed by 1785

Abstract

In the field of bioengineering, depending on the required application, the attachment of various biological entities to the biomaterial is either favored or needs to be prevented. Therefore, different surfaces modification strategies were developed in combination with the characteristics of the materials. The [...] Read more.

In the field of bioengineering, depending on the required application, the attachment of various biological entities to the biomaterial is either favored or needs to be prevented. Therefore, different surfaces modification strategies were developed in combination with the characteristics of the materials. The present contribution reports on the use of the specific surface property of a thermoresponsive polymer poly(N-isopropylacrylamide) pNIPAAM obtained by spin coating in combination with plasma treatment for tuning cell behavior on treated polymeric surfaces. Topographical information for the plasma-treated pNIPAAM coatings obtained by Atomic Force Microscopy (AFM) measurements evidenced a more compact surface for Ar treatment due to combined etching and redeposition, while for oxygen, a clear increase of pores diameter is noticed. The chemical surface composition as determined by X-ray Photoelectron Spectroscopy showed the specific modifications induced by plasma treatment, namely strong oxidation for oxygen plasma treatment illustrated by eight times increase of O-C=O contribution and respectively an increase of C-N/O=C-N bonds in the case of ammonia plasma treatment. Structural information provided by FTIR spectroscopy reveals a significant increase of the carboxylic group upon argon and mostly oxygen plasma treatment and the increase in width and intensity of the amide-related groups for the ammonia plasma treatment. The biological investigations evidenced that L929 fibroblast cells viability is increased by 25% upon plasma treatment, while the cell attachment is up to 2.8 times higher for the oxygen plasma-treated surface compared to the initial spin-coated pNIPAAM. Moreover, the cell detachment process proved to be up to 2–3 times faster for the oxygen and argon plasma-treated surfaces and up to 1.5 times faster for the ammonia-treated surface. These results show the versatility of plasma treatment for inducing beneficial chemical modifications of pNIPAAM surfaces that allows the tuning of cellular response for improving the attachment-detachment process in view of tissue engineering. Full article

(This article belongs to the Special Issue Plasma Processing of Polymers)

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15 pages, 6480 KiB

Open AccessArticle

Adhesive-Free Adhesion between Plasma-Treated Glass-Cloth-Containing Polytetrafluoroethylene (GC–PTFE) and Stainless Steel: Comparison between GC–PTFE and Pure PTFE

by Misa Nishino, Yuki Okazaki, Yosuke Seto, Tsuyoshi Uehara, Katsuyoshi Endo, Kazuya Yamamura and Yuji Ohkubo

Polymers 2022, 14(3), 394; https://doi.org/10.3390/polym14030394 - 20 Jan 2022

Cited by 7 | Viewed by 2107

Abstract

In this study, the effect of plasma treatment on glass-cloth-containing polytetrafluoroethylene (GC–PTFE) was investigated. Previous plasma studies investigated pure PTFE (which does not contain glass cloth) but not GC–PTFE. The effect of Ar + H₂O plasma treatment on GC–PTFE was investigated. [...] Read more.

In this study, the effect of plasma treatment on glass-cloth-containing polytetrafluoroethylene (GC–PTFE) was investigated. Previous plasma studies investigated pure PTFE (which does not contain glass cloth) but not GC–PTFE. The effect of Ar + H₂O plasma treatment on GC–PTFE was investigated. The Ar + H₂O plasma-treated GC–PTFE sheets were thermally compressed to stainless steel (SUS304) foils without using adhesive, and the GC–PTFE/SUS304 adhesion strengths were measured using a 90° peel test. The adhesion strength increased with the increase in the plasma treatment time (0.8 and 1.0 N/mm at 20 s and 300 s, respectively). Thus, strong adhesion between GC–PTFE/SUS304 was achieved without adhesive. This improvement in the adhesion properties of GC–PTFE can be attributed to the generation of oxygen-containing functional groups and the decrease in the surface roughness of the samples. Thereafter, the adhesion properties of GC–PTFE and pure PTFE were compared. Because, unlike pure PTFE, GC–PTFE has no weak boundary layer, GC–PTFE exhibited better adhesion properties than pure PTFE under short plasma treatment times. Full article

(This article belongs to the Special Issue Plasma Processing of Polymers)

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14 pages, 3259 KiB

Open AccessArticle

Effects of He and Ar Heat-Assisted Plasma Treatments on the Adhesion Properties of Polytetrafluoroethylene (PTFE)

by Yuji Ohkubo, Yuki Okazaki, Masafumi Shibahara, Misa Nishino, Yosuke Seto, Katsuyoshi Endo and Kazuya Yamamura

Polymers 2021, 13(23), 4266; https://doi.org/10.3390/polym13234266 - 06 Dec 2021

Cited by 10 | Viewed by 2768

Abstract

Heat-assisted plasma (HAP) treatment using He gas is known to improve the adhesive-bonding and adhesive-free adhesion properties of polytetrafluoroethylene (PTFE). In this study, we investigated the effects of He and Ar gaseous species on the HAP-treated PTFE surface. Epoxy (EP) adhesive-coated stainless steel [...] Read more.

Heat-assisted plasma (HAP) treatment using He gas is known to improve the adhesive-bonding and adhesive-free adhesion properties of polytetrafluoroethylene (PTFE). In this study, we investigated the effects of He and Ar gaseous species on the HAP-treated PTFE surface. Epoxy (EP) adhesive-coated stainless steel (SUS304) and isobutylene–isoprene rubber (IIR) were used as adherents for the evaluation of the adhesive-bonding and adhesive-free adhesion properties of PTFE. In the case of adhesive bonding, the PTFE/EP-adhesive/SUS304 adhesion strength of the Ar-HAP-treated PTFE was the same as that of the He-HAP-treated PTFE. In the case of adhesive-free adhesion, the PTFE/IIR adhesion strength of the Ar-HAP-treated PTFE was seven times lower than that of the He-HAP-treated PTFE. The relation among gaseous species used in HAP treatment, adhesion properties, peroxy radical density ratio, surface chemical composition, surface modification depth, surface morphology, surface hardness, and the effect of irradiation with vacuum ultraviolet (VUV) and UV photons were investigated. The different adhesive-free adhesion properties obtained by the two treatments resulted from the changes in surface chemical composition, especially the ratios of oxygen-containing functional groups and C–C crosslinks. Full article

(This article belongs to the Special Issue Plasma Processing of Polymers)

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22 pages, 9058 KiB

Open AccessArticle

Surface Modification by the DBD Plasma to Improve the Flame-Retardant Treatment for Dyed Polyester Fabric

by Ha-Thanh Ngo, Khanh Vu Thi Hong and The-Bach Nguyen

Polymers 2021, 13(17), 3011; https://doi.org/10.3390/polym13173011 - 06 Sep 2021

Cited by 13 | Viewed by 2978

Abstract

In the first part of the study, dyed polyester fabric was treated with a dielectric barrier discharge (DBD) plasma at 1 W/cm² for 15, 30, 60 and 90 s. The wicking height, tensile strength and color of the control and plasma treated [...] Read more.

In the first part of the study, dyed polyester fabric was treated with a dielectric barrier discharge (DBD) plasma at 1 W/cm² for 15, 30, 60 and 90 s. The wicking height, tensile strength and color of the control and plasma treated fabrics were measured. Results show that the fabric capillary increases with plasma treatment time up to 90 s. However, plasma treatment time longer than 60 s caused an obvious color change and decrease in tensile strength of fabric. Plasma contact time should be such that plasma can improve the hydrophilicity of the fabric and adversely affect the properties of the fabric as little as possible. Thus, the suitable plasma contact time should be less than 60 s. Based on these results, in the second part of the study, three different time levels (15, 20 and 30 s) were selected for plasma pretreatment of this fabric. The plasma-treated fabric was then padded with the flame retardant (FR) (CETAFLAM PDP 30), dried and finally cured at 190 °C for 120 s. The limited oxygen index (LOI) of FR fabrics and the vertical fire characteristics of FR fabric after being washed 5 times also were measured. Comparison of these results with those of FR fabrics without plasma pretreatment shows that plasma pretreatment improves the fabric’s flame retardancy and FR durability. Moreover, it also reduces the heat shrinkage of PET fabric due to high temperature curing. The scanning electron microscopy (SEM) images of the fabric after plasma treatment and FR treatment and the energy-dispersive spectroscopy (EDS) spectrum of the fabric are consistent with the above results. Full article

(This article belongs to the Special Issue Plasma Processing of Polymers)

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22 pages, 7550 KiB

Open AccessArticle

The Effect of DBD Plasma Activation Time on the Dyeability of Woven Polyester Fabric with Disperse Dye

by Thu Nguyen Thi Kim, Khanh Vu Thi Hong, Nguyen Vu Thi and Hai Vu Manh

Polymers 2021, 13(9), 1434; https://doi.org/10.3390/polym13091434 - 29 Apr 2021

Cited by 8 | Viewed by 2377

Abstract

This study consists of two parts. In the first, the woven polyester fabric, after washing to remove lubricant oils, was treated with the dielectric barrier discharge (DBD) plasma at the short plasma exposure time (from 15 to 90 s). The effect of the [...] Read more.

This study consists of two parts. In the first, the woven polyester fabric, after washing to remove lubricant oils, was treated with the dielectric barrier discharge (DBD) plasma at the short plasma exposure time (from 15 to 90 s). The effect of the plasma exposure time on the activation of the polyester fabric was assessed by the wicking height of the samples. The results show that the wicking height in the warp direction of the plasma-treated samples improved but was virtually unchanged in the weft direction. Meanwhile, although the tensile strength in the warp direction of the fabric was virtually unaffected despite the plasma treatment time up to 90 s, in the weft direction it increased slightly with the plasma treatment time. Scanning Electron Microscope (SEM) images and the X-ray Photoelectron Spectroscopy (XPS) spectra of the samples before and after the plasma treatment were used to explain the nature of these phenomena. Based on the results of the first part, in the second part, two levels of the plasma treatment time (30 and 60 s) were selected to study their effect on the polyester fabric dyeability with disperse dyes. The color strength (K/S) values of the dyed samples were used to evaluate the dyeability of the fabric. The SEM images of the dyed samples also showed the difference in the dyeability between the plasma-treated and untreated samples. A new feature of this study is the DBD plasma treatment condition for polyester fabrics. The first is the use of DBD plasma in air (no addition of gas). Second is the very short plasma treatment time (only 15 to 90 s); this condition will be very favorable for the deployment on an industrial scale. Full article

(This article belongs to the Special Issue Plasma Processing of Polymers)

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