Effect of the Plasma Gas Type on the Surface Characteristics of 3Y-TZP Ceramic

Plasma surface treatment can be an attractive strategy for modifying the chemically inert nature of zirconia to improve its clinical performance. This study aimed to clarify the effect of plasma gas compositions on the physicochemical surface modifications of 3 mol% yttria-stabilized zirconia (3Y-TZP). The cold, atmospheric plasma discharges were carried out by using four different plasma gases, which are He/O₂, N₂/Ar, N₂, and Ar from an application distance of 10 mm for 60 s. Static contact angles were measured to define the surface free energy. Changes in elemental composition, surface crystallinity, and surface topography were assessed with X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), confocal laser scanning microscopy (CLSM), and scanning electron microscopy (SEM), respectively. A significant decrease in water contact angle was observed in all plasma groups with the lowest value of 69° in the N₂/Ar group. CLSM and SEM investigations exhibited no morphological changes in all plasma groups. XPS revealed that a reduction in the surface C content along with an increase in O content was pronounced in the case of N₂/Ar compared to others, which was responsible for high hydrophilicity of the surface. XRD showed that the changes in crystallite size and microstrain due to oxygen atom displacements were observed in the N₂/Ar group. The N₂/Ar plasma treatment may contribute to enhancing the bioactivity as well as the bonding performance of 3Y-TZP by controlling the plasma-generated nitrogen functionalities.     

Plasma etching and plasma polymerization coating of carbon fibers. Part 2. Characterization of plasma polymer coated carbon fibers

Unsized AS-4 carbon fibers were subjected to RF plasma etching and/or plasma polymerization coating in order to enhance their adhesion to vinyl ester resin. Ar, N₂ and O₂ were utilized for plasma etching, and acetylene, butadiene and acrylonitrile were used for plasma polymerization coating. Etching and coating conditions were optimized in terms of plasma power, treatment time, and gas (or monomer) pressure by measuring the interfacial adhesion strength. Interfacial adhesion was evaluated using micro-droplet specimens prepared with vinyl ester resin and plasma etched and/or plasma polymer coated carbon fibers. Surface modified fibers were characterized by SEM, XPS, FT-IR, α-Step, dynamic contact angle analyzer (DCA) and tensile strength measurements. Interfacial adhesion between plasma etched and/or plasma polymer coated carbon fibers and vinyl ester resin was reported previously (Part 1), and characterization results are discussed is this paper (Part 2). Gas plasma etching resulted in preferential etching of the fiber surface along the draw direction and decreased the tensile strength, while plasma polymer coatings altered neither the surface topography of fibers nor the tensile strength. Water contact angle decreased with plasma etching, as well as with acrylonitrile and acetylene plasma polymer coatings, but did not change with butadiene plasma polymer coating. FT-IR and XPS analyses revealed the presence of functional groups in plasma polymer coatings.     

Effects of titania content and plasma treatment on the interfacial adhesion mechanism of nano titania-hybridized polyimide and copper system

Nano-titania (TiO₂) incorporated into polyimide (PI) matrix can significantly enhance the adhesion strength for PI/TiO₂ hybrid film and copper system. Surface modifications by various plasma treatments (Ar, Ar/N₂ and Ar/O₂) were also applied in this study to improve the adhesion strength. The Ar/N₂ plasma treatment is regarded as the more effective way in promoting the adhesion strength. The maximum adhesion value of 9.53 N/cm was obtained for the PI/TiO₂-1 wt% hybrid film with Ar/N₂ plasma treatment. It is enhanced about 10 times as large as pristine PI. Furthermore, by Ar/O₂ plasma treatment, a weak boundary of copper oxide was formed at the interlayer between PI/TiO₂ hybrid film and copper which decreases the adhesion strength. The effects of plasma treatment and content of nanosized TiO₂ on the adhesion strength between PI/TiO₂ hybrid film and copper system were studied. Atomic force microscope and contact angle analyses were used to measure the changes in surface morphology and surface energy as a result of plasma treatment. Besides, the interfacial states of peeled-off polymer side and copper side were investigated by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Based on the result of XPS spectra, the peeled-off failure mode between PI/TiO₂ hybrid film and copper was proposed in this study.     

Plasma‐induced solid‐state polymerization modified poly(tetrafluoroethylene) membrane for pervaporation separation of aqueous alcohol mixtures

Acrylamide (AAm) solid state polymerization was induced using argon plasma to improve the pervaporation performance of poly(tetrafluoroethylene) (PTFE) membranes (PTFE‐g‐PAAm) in aqueous alcohol mixtures. The surface morphology, chemical composition, and hydrophilicity changes in the PTFE and PTFE‐g‐PAAm membranes were investigated using ATR‐FTIR, SEM, AFM, X‐ray photoelectron spectroscopy, and water contact angle measurements. The surface hydrophilicity rapidly increased with increasing Ar exposure time, but decreased after longer Ar exposure time because of the degradation in the PTFE‐g‐PAAm membrane grafted layer. Compared with the hydrophilicity of the pristine PTFE membrane (water contact angle = 120°), the argon plasma induced acrylamide (AAm) solid‐state polymerization onto the PTFE surface (water contact angle = 43.3°) and effectively improved the hydrophilicity of the PTFE membrane. This value increases slowly with increasing aging time and then reaches a plateau value of about 50° after 10 days of storage under air. The pervaporation separation performances of the PTFE‐g‐PAAm membranes were higher than that of the pristine PTFE membrane. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:909–919, 2006     

Adhesion mechanisms of silica layers on plasma-treated polymers. Part I. Polycarbonate

We have studied the influence of plasma treatment in various gases (Ar, NH₃, N₂) on the surface modification of polycarbonate (PC) and on the adhesion of plasma-deposited silica layers to PC. Surface modification was investigated using in situ IR ellipsometry, X-ray photoelectron spectroscopy, and contact angle measurements interpreted in terms of electron-acceptor/ donor groups. In addition, in situ UV-visible ellipsometry enabled crosslinking analysis. Due to UV photon emission, Ar plasma treatment induced crosslinking as well as photo-Fries rearrangements and related reactions, thus creating phenolic groups. These groups are acidic sites and are likely to react with the electronegative oxygen atoms of silica. Adhesion of silica to PC, as measured by the micro-scratch test, was enhanced by Ar plasma treatment. The improvement is attributed to the crosslinking of PC, on the one hand, and to acid-base interactions and/or covalent bonding between PC and silica, on the other hand. A further improvement in adhesion was achieved using N₂ plasma treatments (pure or Ar-diluted). These treatments also induced crosslinking and phenolic group formation and, in addition, nitrogen grafting at the surface. Adhesion enhancement from Ar to N₂ treatments is thus attributed to nitrogen-containing groups, which are likely to promote covalent bonding between silica and the treated polymer surface. In contrast, Ar-diluted NH₃ plasma treatment following Ar treatment resulted in decreased adhesion, which is attributed to reduced acidity and low nitrogen grafting.     

Hydrophobic recovery of repeatedly plasma-treated silicone rubber. Part 1. Storage in air

Silicone rubber is used for a wide variety of biomedical and industrial applications due to its good mechanical properties, combined with a hydrophobic surface. Frequently, however, it is desirable to alter the surface hydrophobicity of silicone rubber. Often this is done by plasma treatments but the effects are usually transient. In this study, surfaces of medical grade silicone rubber have been repeatedly modified by means of oxygen, argon, carbon dioxide, and ammonia RF plasma treatments with a 24 h time interval in between treatments. Treated samples were stored in air prior to surface characterization by water contact angle measurements, X-ray photoelectron spectroscopy (XPS), streaming potential measurements, and profilometry for surface roughness. The carbon percentage of the surfaces decreased after plasma treatment, while the silicon and oxygen percentages increased irrespective of the plasma used. The formation of Si-O-Si bridges between siloxane chains after plasma treatment was demonstrated by the appearance of a new component in the Si_2p peak but the degree to which this occurred differed per gas. Streaming potential measurements in a 10 mM potassium phosphate buffer indicated a more negatively charged surface for treated samples compared to untreated samples (-23.3 mV at pH 7.0). Surface roughness increased slightly for repeatedly plasma-treated samples from R_A = 0.35 μm to R_A = 0.46 μm, while scanning electron microscopy showed the presence of several 'cracks' spanning the surface after repeated treatment. Argon, carbon dioxide, and ammonia plasmas significantly reduced the advancing water contact angle from 115° to 58°, 72°, and 85°, respectively, on a more permanent basis (especially when the treatments were repeated after recovery). Oxygen plasma effects on water contact angles generally disappeared within 5 h, also after repeated treatment.     

Study of nisin adsorption on plasma-treated polymer surfaces for setting up materials with antibacterial properties

Setting up antibacterial materials by nisin adsorption on surfaces depends mainly on the surface properties and the surface treatments allowing the modification of such properties. In order to investigate the factors affecting such adsorption, the native low density polyethylene (LDPE) was modified using Argon/Oxygen (Ar/O₂) plasma, nitrogen (N₂) plasma and plasma-induced grafting of acrylic acid (AA). The films were studied by various characterization techniques. The chemical surface modification was confirmed by X-ray photoelectron spectroscopy (XPS), the wettability of the surfaces was evaluated by contact angle measurements, the surface charge was determined by the zeta potential measurements, and the changes in surface topography and roughness were revealed by atomic force microscopy (AFM). Nisin was adsorbed on the native and the modified surfaces. The antibacterial activity, the nisin adsorbed amount, and the peptide distribution were compared for the four nisin-functionalized films. The highest antibacterial activity was recorded on the Ar/O₂ followed by AA then by N₂ treated films and the lowest activity was on the native film. The observed antibacterial activity was correlated to the type of the surface, hydrophobic and hydrophilic interactions, surface charge, surface topography, nisin adsorbed amount, and nisin distribution on the surfaces.     

Surface modification of PVDF hollow fiber membrane to enhance hydrophobicity using organosilanes

This work investigates the membrane modification to enhance hydrophobicity aiming for applications as membrane contactors. The PVDF membranes were activated by NaOH and by plasma activation followed by grafting using three organosilanes. For the NaOH, the contact angle of original membranes (68°) was decreased from 44° to 31° with increasing NaOH concentration from 2.5M to 7.5M at 60°C for 3 h. The contact angle of NaOH treated membranes was increased to 100° after modification with 0.01M FAS‐C8 for 24 h. A needle‐like structure was observed on the membrane surface while there was no significant change in pore size and pore size distribution. Moreover, FTIR and XPS data showed Si peak and composition. The mechanical strength was improved. The surface modified membranes under helium plasma activation followed by grafting with 0.01M FAS‐C8 for 24 h showed higher contact angle, mechanical strength and surface roughness than that obtained by NaOH activation method while other physical properties did not change. The long‐term performance test for 15 days of operation was conducted. The modified membranes exhibited good stability and durability for CO₂ absorption. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Plasma etching and plasma polymerization coating of carbon fibers. Part 1. Interfacial adhesion study

Unsized AS-4 carbon fibers were etched by RF plasma and then coated via plasma polymerization in order to enhance their adhesion to vinyl ester resin. Gases utilized for plasma etching were Ar, N₂ and O₂, while monomers used in plasma polymerization coating were acetylene, butadiene and acrylonitrile. Plasma etchings were carried out as a function of plasma power (30–70 W), treatment time (1–10 min) and gas pressure (20–40 mtorr). Plasma polymerizations were performed by varying the treatment time (15–60 s), plasma power (10–30 W) and gas pressure (20-40 mtorr). The conditions for plasma etching and plasma polymerization were optimized by measuring interfacial adhesion with vinyl ester resin via micro-droplet tests. Plasma etched and plasma polymer coated carbon fibers were characterized by SEM, XPS, FT-IR and α-Step, dynamic contact angle analyzer (DCA) and tensile strength measurements. In Part 1, interfacial adhesion of plasma etched and plasma polymer coated carbon fibers to vinyl ester resin is reported, while characterization results including tensile strength of carbon fibers are reported in Part 2. Among the treatment conditions, a combination of Ar plasma etching and acetylene plasma polymer coating provided greatly improved interfacial shear strength (IFSS) of 69 MPa, compared to 43 MPa obtained from as-received carbon fiber. Based on the SEM analysis of failure surfaces and load-displacement curves, the failure was found to occur at the interface between plasma polymer coating and vinyl ester resin.     

Surface properties of polymers treated with tetrafluoromethane plasma

Polymer films of poly(ethylene terephthalate), polypropylene, and cellophane were surface treated with tetrafluoromethane plasma under different time, power, and pressure conditions. Contact angles for water and methylene iodide and surface energy were analyzed with a dynamic contact angle analyzer. The stability of the treated surfaces was investigated by washing them with water or acetone, followed by contact angle measurements. The plasma treatments decreased the surface energies to 2–20 mJ/m² and consequently enhanced the hydrophobicity and oleophobicity of the materials. The treated surfaces were only moderately affected after washing with water and acetone, indicating stable surface treatments. The chemical composition of the material surfaces was analyzed with X-ray photoelectron spectroscopy (XPS) and revealed the incorporation of about 35–60 atomic % fluorine atoms in the surfaces after the treatments. The relative chemical composition of the C ls spectra's showed the incorporation of —CHF— groups and highly nonpolar —CF₂— and —CF₃ groups in the surfaces and also —CH₂—CF₂— groups in the surface of polypropylene. The hydrophobicity and oleophobicity improved with increased content of nonpolar —CF₂—, —CF₃, and —CH₂—CF₂— groups in the surfaces. For polyester and polypropylene, all major changes in chemical composition, advancing contact angle, and surface energy are attained after plasma treatment for one minute, while longer treatment time is required for cellophane. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1591–1601, 1997     

Improving hydrophobicity on polyurethane-based synthetic leather through plasma polymerization for easy care effect

This study reports on the deposition of a hydrophobic coating on polyurethane (PU)-based synthetic leather through a plasma polymerization method and investigates the hydrophobic behavior of the plasma-coated substrate. The silicon compound of hexamethyldisiloxane (HMDSO), inactive gas argon (Ar), and toluene were used to impart surface hydrophobicity to a PU-based substrate. Surface hydrophobicity was analyzed by water contact angle measurements. Surface hydrophobicity was increased by deposition of compositions of 100% HMDSO, 3:1 HMDSO/toluene, and 1:1 HMDSO/toluene. Optimum conditions of 40 W, 30 s plasma treatment resulted in essentially the same initial contact angle results of approximately 100° for all three treatment compositions. The initial water contact angle for untreated material was about 73°. A water droplet took 1800 s to spread out on the plasma-treated sample after it had been placed on the sample surface. An increase in plasma power also led to a decrease in contact angle, which may be attributed to oxidization of HMDSO during plasma deposition. XPS analysis showed that plasma polymerization of HMDSO/toluene compositions led to a significant increase in atomic percentage of Si compound responsible for the hydrophobic surface. The easy clean results for the treated and untreated PU-based synthetic leather samples clearly showed that the remaining stain on the plasma-polymerized sample was less than that of untreated sample. The plasma-formed coating was both hydrophobic and formed a physical barrier against water and stain.     

Biopolymer brushes grown on PDMS contact lenses by in situ atmospheric plasma-induced polymerization

It is critical for silicone based-contact lens development by improving surface characterization to prevent protein adsorption. In this paper, the silicone (polydimethylsiloxane, PDMS) contact lenses were modified by varied molecular weights of poly(ethylene glycol) methacrylate (PEGMA, Mw 360 and 500 Da) polymer brushes by in situ atmospheric plasma-induced surface copolymerization. After PDMS contact lenses were homogenously immersed in PEGMA monomer solutions, varied gases (oxygen, nitrogen, and argon) with the atmospheric plasma were employed in the process of polymerization. The characterizations of PEGMA polymer brushes modified on the PDMS contact lenses would be evaluated by atomic force microscopy, FT-IR spectroscopy, X-ray photoelectron spectroscopy, and contact angle test. The results show that the hydrophilicity of the PEGMA polymer brush-modified surface is obviously improved. The contact angle of PEGMA-modified surface decreases about 20°–40° by varied atmospheric plasma (O₂, N₂, and Ar gases), compared to the pristine lenses. Importantly, the hydrophilicity of the PEGMA polymer brush-modified surface could be retained beyond 2 weeks. PEGMA-modified PDMS contact lenses also display superior anti-protein (fibrinogen and human serum bovine) adsorption ability. Therefore, immobilization of PEGMA polymer brushes by in situ atmospheric plasma-induced polymerization would be a great and rapid method to enhance the hydrophilicity and anti-protein adsorption ability in the PDMS contact lenses.     

Treatment with Ar–O2 low-pressure plasma of vulcanized rubber sole containing noticeable amount of processing oils for improving adhesion to upper in shoe industry

Vulcanized rubber (L3 rubber) containing intentionally noticeable excess of processing oils in its formulation was treated with Argon–Oxygen (Ar–O₂) (2:1, vol/vol) low-pressure (LP) plasma for achieving a satisfactory level of adhesion to waterborne polyurethane adhesive. The effectiveness of the Ar–O₂ LP plasma treatment of L3 rubber depended on both the configuration of the plasma chamber shelves and the treatment time. Surface modifications were assessed by attenuated total reflectance-IR and X-ray photoelectron spectroscopy, contact angle measurements, and scanning electron microscopy. Ar–O₂ LP plasma treatment in direct configuration provided the most effective surface modification of the L3 rubber, and the increase in the treatment time improved the extent of the surface modifications. However, even important surface modifications were produced by Ar–O₂ LP plasma treatment, adhesion of treated L3 rubber was not improved due to the creation of weak boundary layer at the polyurethane–rubber interface after joint formation. Heating at 80 °C for 12 h of the as-received L3 rubber prior to Ar–O₂ LP plasma treatment enhanced the extent of the surface modifications, and improved adhesion was obtained for Ar–O₂ LP plasma treatment times higher than 600 s.     

Studies on plasma polymerization of hexamethyldisiloxane in the presence of different carrier gases

Plasma polymerization of hexamethyldisiloxane(HMDSO) in the presence of different carrier gases such as H₂, He, N₂, Ar, and O₂ was carried out using an inductively coupled electrodeless glow discharge. The polymerization kinetics showed that the monomer HMDSO plasma‐polymerized at different rates from low to high for the carrier gases H₂, He, N₂, Ar, and O₂ in that order. The products were studied using FTIR, electron spectroscopy for chemical analysis, and elemental analysis. The results indicated that HMDSO molecules underwent different degrees of fragmentation in plasma polymerization for different carrier gases and radio frequency (RF) powers. The polymer deposition rate and the structures of products were mainly dependent on molecular fragmentation, which varied with carrier gas and imposed RF power. O₂ and H₂ gases can incorporate in the plasma polymers to form products containing more oxygen or hydrogen components, while other gases such as N₂ have no detectable component in products. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1434–1438, 2001     

Cotton fabric graft copolymerization using microwave plasma. I. Universal attenuated total reflectance–FTIR study

The effect of microwave plasma on lightweight cotton fabric was investigated. N₂‐plasma, O₂‐plasma, and Ar‐plasma were obtained using a microwave generator at 2.45 GHz under vacuum. The universal attenuated total reflectance–Fourier transform infrared (UATR–FTIR) instrument was used to monitor the changes created after N₂‐, O₂‐, and Ar‐plasma treatments. The exposure of cotton fabrics to the plasma for 240 s with a microwave power of 500 W was sufficient to create active carbonyl groups, as shown by the presence of a peak around 1725 cm^?1 in the FTIR spectra of the treated cotton fabrics. Ar‐plasma was found to generate more active groups than N₂‐ and O₂‐plasmas. The active centers created within the cellulose chains were used to initiate copolymerization reactions with vinyl monomers to impart hydrophobic character to lightweight cotton fabric. The efficiency of the grafting process and the presence of grafted monomers on fabric surface were confirmed using UATR–FTIR. Testing of treated fabric revealed that excellent water repellency was obtained. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 145–154, 2004     

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.     

Surface energy of the plasma treated Si incorporated diamond-like carbon films

Surface energy and surface chemical bonds of the plasma treated Si incorporated diamond-like carbon films (Si-DLC) were investigated. The Si-DLC films were prepared by r.f. plasma assisted chemical vapor deposition using benzene and diluted silane (SiH₄/H₂ = 10:90) as the precursor gases. The Si-DLC films were subjected to plasma treatment using various gases like N₂, O₂, H₂ and CF₄. The plasma treated Si-DLC films showed a wide range of water contact angles from 13.4° to 92.1°. The surface energies of the plasma treated Si-DLC films revealed a high polar component for O₂ plasma treated Si-DLC films and a low polar component for CF₄ plasma treated Si-DLC films. The CF₄ plasma treated Si-DLC films indicated the minimum surface energy. X-ray photoelectron spectroscopy (XPS) revealed that the polarizability of the bonds present on the surface explains the hydrophilicity and hydrophobicity of the plasma treated Si-DLC films. We also suggest that the O₂ plasma treated surface can provide an excellent hemocompatible surface from the estimated interfacial energy between the plasma treated Si-DLC surface and human blood.     

Adhesion of microwave‐plasma‐treated fluoropolymers to thermoset vinylester

Poly(tetrafluoroethylene) and a fluoroethylene copolymer were surface treated with a 2.45‐GHz microwave plasma to enhance their adhesion to a vinylester thermoset. The plasmas were generated with an inert gas (Ar) and with reactive gases (H₂, O₂, and N₂). The lap‐joint shear stress was measured on fluoropolymer samples glued with the vinylester. In general, the stress at failure increased with increasing plasma‐energy dose. The H₂ plasma yielded the best adhesion, and X‐ray photoelectron spectroscopy revealed that it yielded the highest degree of defluorination of the fluoropolymer surface. The defluorination efficiency declined in the order H₂, Ar, O₂, and N₂. Contact angle measurements and scanning electron microscopy revealed that the surface roughness of the fluoropolymer depended on the rate of achieving the target energy dose. High power led to a smoother surface, probably because of a greater increase in temperature and partial melting. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 838–842, 2005     

Controlling the surface wettability of poly(sulfone) films by UV‐assisted treatment: benefits in relation to plasma treatment

Hydrophilic and superhydrophilic surfaces of poly(sulfone) (PSU) thin films were prepared by UV irradiation in the presence of O₂ or acrylic acid (AA) vapor. Treated surfaces were then investigated by water contact angle measurements, Fourier transformed IR spectroscopy in attenuated total reflectance mode (FTIR‐ATR), X‐ray photoelectron spectroscopy (XPS), near‐edge X‐ray absorption fine structure (NEXAFS) and AFM. Water contact angle values of treated PSU films using either O₂ or AA vapor as the reactive atmosphere reached about 6° after more than 120 min of irradiation. FTIR‐ATR, XPS and NEXAFS analysis showed incorporation of oxygenated groups onto the surface that led to its hydrophilic characteristics. In addition, when AA vapor was used as the reactive atmosphere, a photopolymerization process of poly(acrylic acid) onto the surface of the PSU was observed. AFM analysis showed a very low level of roughness after the treatments. A comparison of UV‐assisted surface modifications of PSU films with traditional plasma treatments showed excellent qualitative agreement between the two techniques. Our results show that UV‐assisted treatments in the presence of AA vapor or O₂ are efficient ways of controlling the surface wettability and functionalities grafted on the surface of PSU films. This treatment can be considered as a permanent dry grafting method that resists aging and uses a simple experimental setup. © 2012 Society of Chemical Industry     

Plasma induced grafting of PSt onto titanium dioxide powder. II

Grafting of polystyrene (PSt) onto titanium dioxide powder was investigated in this study. The graft polymerization reaction was induced by N₂ plasma treatment of the surfaces of the titanium dioxide powder. IR and XPS results showed that PSt was grafted onto the titanium dioxide powder. The crystal structure of the titanium dioxide powder observed by XRD spectra was unchanged after plasma graft polymerization. In the grafting reaction, the grafting yield increased with the plasma power, the plasma treatment time, and the grafting reaction, but it increased first then decreased after reaching 50°C. The type of monomers also has an effect on the grafting yield. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2112–2117, 2005