scholarly journals Effect of VUV Radiation on Surface Modification of Polystyrene Exposed to Atmospheric Pressure Plasma Jet

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1136 ◽  
Author(s):  
Rok Zaplotnik ◽  
Alenka Vesel
Keyword(s):  
Functional Groups ◽  
Photoelectron Spectroscopy ◽  
Polymer Surface ◽  
Argon Plasma ◽  
Plasma Jet ◽  
Contact Angles ◽  
Surface Wettability ◽  
Water Contact ◽  
Xps Spectra ◽  
Sharp Interfaces

Precise tailoring of surface properties by gaseous plasma treatments remains a key scientific challenge, especially when adequate surface wettability should be laterally distributed, and sharp interfaces between hydrophobic and hydrophilic areas are desirable. The evolution of surface wettability and functional groups on polystyrene (PS) upon treatment with argon plasma jet was monitored by water contact angles and X-ray photoelectron spectroscopy (XPS). An array of water droplets was deposited on PS samples treated either directly by the plasma jet or only VUV radiation arising from the plasma. Rather sharp interfaces between the activated and not-affected regions were observed in both cases. The functionalization with highly-oxidized carbon functional groups, as determined by high-resolution C1s XPS spectra, was by far more efficient using the VUV radiation only. In contrast, the optimal wettability was achieved using direct plasma treatment. The results were explained by different mechanisms involved in the interaction of radiation and reactive plasma species with the polymer surface.

scholarly journals Investigation of Surface Modification of Polystyrene by a Direct and Remote Atmospheric-Pressure Plasma Jet Treatment

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2435
Author(s):  
Alenka Vesel ◽  
Gregor Primc
Keyword(s):  
Functional Groups ◽  
Atmospheric Pressure ◽  
Treatment Time ◽  
Polymer Surface ◽  
Atmospheric Pressure Plasma ◽  
Plasma Jet ◽  
Contact Angles ◽  
Surface Wettability ◽  
Atmospheric Pressure Plasma Jet ◽  
Pressure Plasma

Localized functionalization of polymer surface with an atmospheric-pressure plasma jet was investigated at various treatment conditions. Polystyrene samples were treated with the plasma jet sustained in argon under direct or remote conditions. The two-dimensional evolution of surface wettability and the spot size of the treated area was determined systematically by measuring apparent water contact angles. Modification of surface chemistry and the formation of functional groups were investigated by X-ray photoelectron spectroscopy (XPS). The saturation of surface wettability and functional groups was observed even after a second of treatment providing the sample was placed close to the exhaust of the discharge tube. The spot diameter of the modified area increased logarithmically with increasing treatment time. However, it decreased linearly when increasing the distance. At the edge of the glowing plasma, however, the modification of surface properties was more gradual, so even 30 s of treatment caused marginal effects. With a further increase in the distance from the edge of the glowing plasma, however, there were no further treatment effects. The results are explained by significant axial as well as radial gradients of reactive species, in particular hydroxyl radicals.

scholarly journals Non-Equilibrium Plasma Methods for Tailoring Surface Properties of Polyvinylidene Fluoride: Review and Challenges

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4243
Author(s):  
Alenka Vesel ◽  
Rok Zaplotnik ◽  
Gregor Primc ◽  
Miran Mozetič ◽  
Tadeja Katan ◽  
...  
Keyword(s):  
Surface Modification ◽  
Surface Properties ◽  
Photoelectron Spectroscopy ◽  
Polyvinylidene Fluoride ◽  
Polymer Surface ◽  
Argon Plasma ◽  
Standard Technique ◽  
Water Contact ◽  
Plasma Methods ◽  
Non Equilibrium

Modification and functionalization of polymer surface properties is desired in numerous applications, and a standard technique is a treatment with non-equilibrium gaseous plasma. Fluorinated polymers exhibit specific properties and are regarded as difficult to functionalize with polar functional groups. Plasma methods for functionalization of polyvinylidene fluoride (PVDF) are reviewed and different mechanisms involved in the surface modification are presented and explained by the interaction of various reactive species and far ultraviolet radiation. Most authors used argon plasma but reported various results. The discrepancy between the reported results is explained by peculiarities of the experimental systems and illustrated by three mechanisms. More versatile reaction mechanisms were reported by authors who used oxygen plasma for surface modification of PVDF, while plasma sustained in other gases was rarely used. The results reported by various authors are analyzed, and correlations are drawn where feasible. The processing parameters reported by different authors were the gas pressure and purity, the discharge configuration and power, while the surface finish was predominantly determined by X-ray photoelectron spectroscopy (XPS) and static water contact angle (WCA). A reasonably good correlation was found between the surface wettability as probed by WCA and the oxygen concentration as probed by XPS, but there is hardly any correlation between the discharge parameters and the wettability.

scholarly journals P4VP Modified Zwitterionic Polymer for the Preparation of Antifouling Functionalized Surfaces

Nanomaterials ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 706 ◽  
Author(s):  
Chaoqun Wu ◽  
Yudan Zhou ◽  
Haitao Wang ◽  
Jianhua Hu
Keyword(s):  
Photoelectron Spectroscopy ◽  
Cell Attachment ◽  
Raft Polymerization ◽  
Polymer Brush ◽  
Contact Angles ◽  
Polymerization Process ◽  
Water Contact ◽  
Zwitterionic Polymers ◽  
Ito Glass ◽  
Zwitterionic Polymer

Zwitterionic polymers are suitable for replacing poly(ethylene glycol) (PEG) polymers because of their better antifouling properties, but zwitterionic polymers have poor mechanical properties, strong water absorption, and their homopolymers should not be used directly. To solve these problems, a reversible-addition fragmentation chain transfer (RAFT) polymerization process was used to prepare copolymers comprised of zwitterionic side chains that were attached to an ITO glass substrate using spin-casting. The presence of 4-vinylpyridine (4VP) and zwitterion chains on these polymer-coated ITO surfaces was confirmed using 1H NMR, FTIR, and GPC analyses, with successful surface functionalization confirmed using water contact angle, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) studies. Changes in water contact angles and C/O ratios (XPS) analysis demonstrated that the functionalization of these polymers with β-propiolactone resulted in hydrophilic mixed 4VP/zwitterionic polymers. Protein adsorption and cell attachment assays were used to optimize the ratio of the zwitterionic component to maximize the antifouling properties of the polymer brush surface. This work demonstrated that the antifouling surface coatings could be readily prepared using a “P4VP-modified” method, that is, the functionality of P4VP to modify the prepared zwitterionic polymer. We believe these materials are likely to be useful for the preparation of biomaterials for biosensing and diagnostic applications.

scholarly journals Synthesis of amphiphilic ABA triblock oligomer via ATRP and its surface properties

2017 ◽  
Vol 95 (5) ◽  
pp. 605-611 ◽  
Author(s):  
Lei Wang ◽  
Shaoqing Wen ◽  
Zhanxiong Li
Keyword(s):  
Photoelectron Spectroscopy ◽  
Microphase Separation ◽  
Gel Permeation Chromatography ◽  
Contact Angles ◽  
Chemical Compositions ◽  
Water Contact ◽  
Force Microscopy ◽  
Atomic Force ◽  
Poly Ethylene ◽  
Magnetic Resonances

A series of novel amphiphilic ABA-type poly(tridecafluorooctylacrylate)-poly(ethylene glycol)-poly(tridecafluorooctylacrylate) (henceforth referred to as p-TDFA-PEG-p-TDFA) triblock oligomers were successfully synthesized via atom transfer radical polymerization (ATRP) using well-defined Br-PEG-Br as macroinitiator and copper as catalyst. The block oligomers were characterized by Fourier transform infrared (FTIR) spectroscopy and 1H and 19F nuclear magnetic resonances (NMR). Gel permeation chromatography (GPC) showed that the block oligomers have been obtained with narrow molecular weight distributions of 1.22–1.33. X-ray photoelectron spectroscopy (XPS) was carried out to confirm the attachment of p-TDFA-PEG-p-TDFA onto the silicon substrate, together with the chemical compositions of p-TDFA-PEG-p-TDFA. The wetabilities of the oligomer films were measured by water contact angles (CAs). Water CAs of p-TDFA-PEG-p-TDFA film were measured and their morphologies were tested by atomic force microscopy (AFM). The result showed that the CAs of the oligomer films, which possess fluoroalkyl groups assembled on the outer surface, increase after heating due to the migration of fluoroalkyl groups and the resulted microphase separation of the p-TDFA-PEG-p-TDFA.

Effects of Surface Wettability on Heterogeneous Boiling

2009 ◽  
Author(s):  
Hai Trieu Phan ◽  
Nadia Caney ◽  
Philippe Marty ◽  
Ste´phane Colasson ◽  
Je´roˆme Gavillet
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Nucleate Boiling ◽  
Contact Angles ◽  
Surface Wettability ◽  
Water Contact ◽  
New Approach ◽  
Major Subject ◽  
Nucleate Boiling Heat Transfer ◽  
Classical Models

Although boiling process has been a major subject of research for several decades, its physics still remain unclear and require further investigation. This study aims at highlighting the effects of the surface wettability on pool boiling heat transfer. Nanocoating techniques were used to vary the water contact angle from 20 to 110° by modifying nanoscale surface topography and chemistry. The experimental results obtained disagree with the predictions of the classical models. A new approach of nucleation mechanism is established to clarify the nexus between the surface wettability and the nucleate boiling heat transfer. In this approach, we introduce the concept of macro- and micro-contact angles to explain the observed phenomenon.

scholarly journals Surface Properties of Pine Scrimber Panels with Varying Density

Coatings ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 397 ◽  
Author(s):  
Jinguang Wei ◽  
Qiuqin Lin ◽  
Yahui Zhang ◽  
Wenji Yu ◽  
Chung-Yun Hse ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Surface Properties ◽  
Photoelectron Spectroscopy ◽  
Lower Surface ◽  
Contact Angles ◽  
High Density ◽  
Water Contact ◽  
Change Rate ◽  
Hydrophilic Material ◽  
Wood Grain

Coating quality for scrimber products against exterior conditions is largely dependent on the surface properties. The wettability, morphology, and chemical composition of pine scrimber surfaces were investigated to better understand the surface properties. The scrimber was found to be a hydrophilic material because the water contact angles were less than 90°. The panels with a density of 1.20 g/cm3 had the largest angle change rate (k = 0.212). As the panel density increased, the instantaneous contact angle of each test liquid (i.e., water, formamide, and diiodomethane) on the panels decreased, and so did surface free energy. Panels with higher density showed lower surface roughness. Surface roughness across the wood grain was greater than that along the grain. SEM observations showed the high-density panels had a smoother surface with fewer irregular grooves in comparison with the low-density panels. X-ray photoelectron spectroscopy (XPS) analysis indicated that more unoxygenated groups appeared on the surface of high-density panels.

scholarly journals Functionalization of Neutral Polypropylene by Using Low Pressure Plasma Treatment: Effects on Surface Characteristics and Adhesion Properties

Polymers ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 202 ◽  
Author(s):  
Chiara Mandolfino ◽  
Enrico Lertora ◽  
Carla Gambaro ◽  
Marco Pizzorni
Keyword(s):  
Surface Morphology ◽  
Photoelectron Spectroscopy ◽  
Polymeric Materials ◽  
Low Pressure ◽  
Contact Angles ◽  
Bonded Joints ◽  
Water Contact ◽  
Adhesion Properties ◽  
Pressure Plasma ◽  
Low Pressure Plasma

Polyolefins are considered among the most difficult polymeric materials to treat because they have poor adhesive properties and high chemical barrier responses. In this paper, an in-depth study is reported for the low pressure plasma (LPP) treatment of neutral polypropylene to improve adhesion properties. Changes in wettability, chemical species, surface morphology and roughness of the polypropylene surfaces were evaluated by water contact angle measurement, X-ray photoelectron spectroscopy and, furthermore, atomic force microscopy (AFM). Finally, the bonded joints were subjected to tensile tests, in order to evaluate the practical effect of changes in adhesion properties. The results indicate that plasma is an effective treatment for the surface preparation of polypropylene for the creation of bonded joints: contact angles decreased significantly depending on the plasma-parameter setup, surface morphology was also found to vary with plasma power, exposure time and working gas.

scholarly journals Surface wettability of plasma SiO x :H nanocoating-induced endothelial cells' migration and the associated FAK-Rho GTPases signalling pathways

2011 ◽  
Vol 9 (67) ◽  
pp. 313-327 ◽  
Author(s):  
Yang Shen ◽  
Guixue Wang ◽  
Xianliang Huang ◽  
Qin Zhang ◽  
Jiang Wu ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Rho Gtpases ◽  
Vascular Endothelial Cell ◽  
Contact Angles ◽  
Surface Wettability ◽  
Signalling Pathways ◽  
Hydrophobic Surfaces ◽  
Water Contact ◽  
Hydrophilic Surfaces ◽  
And Migration

Vascular endothelial cell (EC) adhesion and migration are essential processes in re-endothelialization of implanted biomaterials. There is no clear relationship and mechanism between EC adhesion and migration behaviour on surfaces with varying wettabilities. As model substrates, plasma SiO x :H nanocoatings with well-controlled surface wettability (with water contact angles in the range of 98.5 ± 2.3° to 26.3 ± 4.0°) were used in this study to investigate the effects of surface wettability on cell adhesion/migration and associated protein expressions in FAK-Rho GTPases signalling pathways. It was found that EC adhesion/migration showed opposite behaviour on the hydrophilic and hydrophobic surfaces (i.e. hydrophobic surfaces promoted EC migration but were anti-adhesions). The number of adherent ECs showed a maximum on hydrophilic surfaces, while cells adhered to hydrophobic surfaces exhibited a tendency for cell migration. The focal adhesion kinase (FAK) inhibitor targeting the Y-397 site of FAK could significantly inhibit cell adhesion/migration, suggesting that EC adhesion and migration on surfaces with different wettabilities involve ( p )FAK and its downstream signalling pathways. Western blot results suggested that the FAK-Rho GTPases signalling pathways were correlative to EC migration on hydrophobic plasma SiO x :H surfaces, but uncertain to hydrophilic surfaces. This work demonstrated that surface wettability could induce cellular behaviours that were associated with different cellular signalling events.

The Use of X-Ray Photoelectron Spectroscopy for the Study of Oral Streptococcal Cell Surfaces

1997 ◽  
Vol 11 (4) ◽  
pp. 388-394 ◽  
Author(s):  
H.C. Van Der Mei ◽  
H.J. Busscher
Keyword(s):  
Cell Surface ◽  
Photoelectron Spectroscopy ◽  
Surface Composition ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Contact Angles ◽  
Microbial Cell ◽  
Cell Surfaces ◽  
Water Contact ◽  
X Ray

Physicochemical and structural properties of microbial cell surfaces play an important role in their adhesion to surfaces and are determined by the chemical composition of the outermost cell surface. Many traditional methods used to determine microbial cell wall composition require fractionation of the organisms and consequently do not yield information about the composition of the outermost cell surface. X-ray photoelectron spectroscopy (XPS) measures the elemental composition of the outermost cell surfaces of micro-organisms. The technique requires freeze-drying of the organisms, but, nevertheless, elemental surface concentration ratios of oral streptococcal cell surfaces with peritrichously arranged surface structures showed good relationships with physicochemical properties measured under physiological conditions, such as zeta potentials. Isoelectric points ap-peared to be governed by the relative abundance of oxygen- and nitrogen-containing groups on the cell surfaces. Also, the intrinsic microbial cell-surface hydrophobicity by water contact angles related to the cell-surface composition as by XPS and was highest for strains with an elevated isoelectric point. Inclusion of elemental surface compositions for tufted streptococcal strains caused deterioration of the relationships found. Interestingly, hierarchical cluster analysis on the basis of the elemental surface compositions revealed that, of 36 different streptococcal strains, only four S. rattus as well as nine S. mitis strains were located in distinct groups, well separated from the other streptococcal strains, which were all more or less mixed in one group.

Diamond-Like Carbon Films for Silicon Passivation in Microelectromechanical Devices

1995 ◽  
Vol 383 ◽  
Author(s):  
M. R. Houston ◽  
R. T. Howe ◽  
K Komvopoulos ◽  
R. Maboudian
Keyword(s):  
Contact Angle ◽  
Surface Properties ◽  
Photoelectron Spectroscopy ◽  
Microelectromechanical Systems ◽  
Adhesion Force ◽  
Contact Angles ◽  
Vacuum Arc ◽  
Diamond Like Carbon ◽  
Adhesion Forces ◽  
Water Contact

ABSTRACTThe surface properties of diamond-like carbon (DLC) films deposited by a vacuum arc technique on smooth silicon wafers are presented with specific emphasis given to stiction reduction in microelectromechanical systems (MEMS). The low deposition temperatures afforded by the vacuum arc technique should allow for easy integration of the DLC films into the current fabrication process of typical surface micromachines by means of a standard lift-off processing technique. Using X-ray photoelectron spectroscopy (XPS), contact angle analysis, and atomic force microscopy (AFM), the surface chemistry, microroughness, hydrophobicity, and adhesion forces of DLC-coated Si(100) surfaces were measured and correlated to the measured water contact angles. DLC films were found to be extremely smooth and possess a water contact angle of 87°, which roughly corresponds to a surface energy of 22 mJ/m2. It is shown that the pull-off forces measured by AFM correlate well with the predicted capillary forces. Pull-off forces are reduced on DLC surfaces by about a factor of five compared to 10 nN pull-off forces measured on the RCA-cleaned silicon surfaces. In the absence of meniscus forces, the overall adhesion force is expected to decrease by over an order of magnitude to the van der Waals attractive force present between two DLC-coated surfaces- To further improve the surface properties of DLC, films were exposed to a fluorine plasma which increased the contact angle to 99° and lowered the pull-off force by approximately 20% over that obtained with as-deposited DLC. The significance of these results is discussed with respect to stiction reduction in micromachines.

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