Increase In Surface Energy Research Articles

Effect of surface mechanical attrition treatment of titanium using alumina balls: surface roughness, contact angle and apatite forming ability

The effect of surface mechanical attrition treatment (SMAT) of commercially pure titanium (CP-Ti) using 8mm O alumina balls was studied. SMAT induced plastic deformation, increased the surface roughness, reduced the grain size and decreased the contact angle (from 64° to 43°) with a corresponding increase in surface energy (from 32 to 53 mJ/m2). Untreated CP-Ti and those treated using alumina balls for 900 s reveals no apatite growth until the 28th day of immersion whereas those treated for 1800 and 2700 s exhibit apatite growth in selective areas and the extent of growth is increased with increase in immersion time in SBF. The study reveals that SMAT using alumina balls is beneficial in imparting the desired surface characteristics, provided the surface contamination is limited, which would otherwise decrease the apatite forming ability.

Surface Treatment of Polyethylene Terephthalate to Improving Hydrophilicity Using Atmospheric Pressure Plasma Jet

In this paper, the effects of atmospheric pressure argon (Ar) plasma jet treatments on the surface properties of polyethylene terephthalate films are studied. Different discharge power density, treatment distance, and treatment time are selected to study the effects of discharge operation parameters on the surface treatments, and the surface properties of the untreated and plasma-treated samples are characterized through water contact angle and surface energy measurement, Fourier transformed infrared spectroscopy and X-ray photoelectron spectroscopy, with the modification mechanism being discussed. Results show that after the atmospheric pressure Ar plasma jet treatment, the water contact angle decreases with the increase of treatment time and surface energy increases with the increase of treatment time, and both of them reach saturated value at certain treatment time. It is found that, the shorter the treatment distance and the higher discharge power density are, the greater are the water contact angle decreasing and surface energy increasing, and the introduction of oxygen-containing polar groups is the main reason for the improvement of surface hydrophilicity. Therefore by shorting treatment distance and increasing the discharge power density, more oxygen-containing polar groups are generated in the jet, thus the treatment time to obtain the efficient treatment effect is reduced.

폴리카보네이트 필름 표면 처리가 증착 SiOx베리어층 접착에 미치는 영향

폴리카보네이트(PC) 필름을 유연기판으로 사용하기 위해서는 <TEX>$SiO_x$</TEX> 증착에 의한 베리어 특성 개선이 필요하며 이때 베리어 층과 PC 계면 접착력이 매우 중요하다. 본 연구에서는 언더 코팅, UV/<TEX>$O_3$</TEX> 및 저온 플라즈마와 같은 다양한 표면 처리 방법에 의하여 PC 필름 표면을 개질하여 표면의 물리적 화학적 변화가 증착된 베리어 층 계면 접착력에 미치는 영향을 살펴보았다. 표면 처리 전의 PC 필름은 표면 거칠기 및 표면 에너지가 매우 낮아 <TEX>$SiO_x$</TEX> 베리어 층과의 접착력이 현저히 떨어짐을 알 수 있었다. PC 필름을 저온 플라즈마로 표면 처리한 결과, 표면의 거칠기 증가와 극성 관능기 생성에 의하여 극성 표면 에너지가 향상되는 반면 UV/<TEX>$O_3$</TEX> 처리의 경우, 표면 거칠기 변화 없이 표면에 생성된 극성 관능기에 의해 극성 표면 에너지가 증가됨을 알 수 있었다. 이러한 표면의 변화는 베리어층과 PC 기판의 계면 접착력 증가에 기여함을 알 수 있었다. 표면 처리 방법으로 언더 코팅을 사용하는 경우 표면에 에너지를 가하지 않아도 코팅제의 아크릴산과 <TEX>$SiO_x$</TEX>의 접착력 향상에 의하여 PC 필름과의 계면 접착력이 증가되며 유무기 하이브리드 다층 구조에 의한 베리어 특성 개선이 함께 일어남을 알 수 있었다. The interfacial adhesion strength is very important in <TEX>$SiO_x$</TEX> deposited PC film for the barrier enhanced polycarbonate (PC) flexible substrate. In this study, PC films were treated by undercoating, UV/<TEX>$O_3$</TEX> and low temperature plasma and then the effect of physical and chemical surface modifications on the interfacial adhesion strength between PC film and <TEX>$SiO_x$</TEX> barrier layer were studied. It was found that untreated PC film shows significantly low interfacial adhesion strength due to the smooth surface and low surface free energy of PC. Low temperature plasma treatments resulted in the increase of both surface roughness and surface free energy due to etching and the appearance of polar molecules on the PC surface. However, UV/<TEX>$O_3$</TEX> treatment only shows the increase of surface free energy by developed polar molecules on the surface. These surface modifications caused the enhancement of surface interfacial strength between PC film and <TEX>$SiO_x$</TEX> barrier. In the case of undercoating, it was found that the increase of surface interfacial strength was achieved by adhesion between various acrylic acid on acrylate coated surface and <TEX>$SiO_x$</TEX> without increase of polar surface energy. In addition, the barrier property is also improved by organic-inorganic hybrid multilayer structure.

The effects of enhancing the surface energy of a polystyrene plate by air atmospheric pressure plasma jet on early attachment of fibroblast under moving incubation

Enhancing the biomaterial surface energy has received wide attention as a possible option for improving cell adhesion. Non-thermal atmospheric pressure plasma jets (APPJ) have been introduced to medical fields as one of the on-site treatment methods to enhance surface energy before implantation. The aim of this study is to evaluate the effect of enhancing the surface energy of a polystyrene plate by air APPJ on the early attachment of fibroblasts under moving incubation. In addition, the range of plasma jet effect was measured for easy on-site application. After 2min of air APPJ treatment, mouse fibroblasts (L929) were separately seeded through the prepared holes on the treated polystyrene plate as well as as-received polystyrene plate. Cells were allowed to attach for 30min or 4h under 70 revolutions per minute. The surface characteristic results confirmed the increase of surface energy six times after air APPJ treatment with the Owens–Wendt method. Minimal change of surface temperature and amine functional group without roughness changes were detected. In the case of a short attachment time (30min), the attached L929 were only found on air APPJ-treated center surface. In 4h attachment time, cells were attached with vinculin focal adhesion and elongated actin filament on the both the right and left side surfaces from the center area which was treated by the plasma jet flame. In light of this study, air APPJ could be useful for early-rapid attachment of mouse fibroblasts on polystyrene plates under moving incubation. Future studies can examine its on-site use with biomaterials.

Effect of sputtering power on friction coefficient and surface energy of co-sputtered titanium and molybdenum disulfide coatings and its performance in micro hot-embossing

Si micromolds are common for fabrication of polymer-based microfluidic devices by hot-embossing because of the well established fabrication methods for Si, e.g., deep reactive ion etching, for favorable surface finish and accuracy. The problems with low yield, poor reproducibility, premature failure and limited lifetime of a Si micromold are induced by high friction and surface adhesion generated during demolding. Therefore, Titanium (Ti) and molybdenum disulfide (MoS2) coatings were deposited on Si micromolds via magnetron co-sputtering at various combinations of target powers to improve its surface properties. Coating composition, crystallographic orientation, roughness, critical load, hardness, friction coefficient and surface energy were measured by X-ray photoelectron spectroscopy, X-ray diffraction, atomic force microscopy, scratch testing, nanoindentation, ball-on-disc tribometry and the contact angle method respectively. A statistical design of experiment matrix was used to investigate the effect of the Ti and MoS2 target powers on the friction coefficient and surface energy of the coatings. From this designed experiment, it was observed that increasing MoS2 target power was associated with increasing surface energy and decreasing friction coefficient and target powers had statistically significant effects on these parameters. Crystallinity, roughness and hardness of the coatings increased with increasing Ti concentration. A mathematical model of the effects of Ti and MoS2 target powers on the friction coefficient and surface energy of the coatings has been fit to the experimental results using the response surface method. Uncoated and MoS2–Ti coated Si micromolds were used in hot-embossing for a comparative study on replication performance of uncoated and various coated micromolds. Hotembossed PMMA microstructures showed that coating improve replication performance of Si micromolds. Si micromold coated with co-sputter of Ti and MoS2 at power of 300 and 75 W respectively, showed better replication quality among the selected target powers.

Self Assembly of Nanoislands on YSZ-(001) Surface: A Mechanistic Approach Toward a Robust Process

We experimentally investigate the mechanism of formation of self-assembled arrays of nanoislands surrounding dopant sources on the (001) surface of yttria-stabilized zirconia. Initially, we used lithographically defined thin-film patches of gadolinia-doped ceria (GDC) as dopant sources. During annealing at approximately one-half the melting temperature of zirconia, surface diffusion of dopants leads to the breakup of the surface around the source, creating arrays of epitaxial nanoislands with a characteristic size (~100 nm) and alignment along elastically compliant directions, <110>. The breakup relieves elastic strain energy at the expense of increasing surface energy. On the basis of understanding the mechanism of island formation, we introduce a simple and versatile powder-based doping process for spontaneous surface patterning. The new process bypasses lithography and conventional vapor-source doping, opening the door to spontaneous surface patterning of functional ceramics and other refractory materials. In addition to using GDC solid-solution powders, we demonstrate the effectiveness of the process in another system based on Eu2O3.

Dynamic simulation of particle packing influenced by size, aspect ratio and surface energy

The multi-sphere method and JKR model are used in the discrete element method simulation to investigate the effect of the particle size, aspect ratios, and cohesiveness on the packing structure, characterized by porosity, radial distribution function (RDF), coordination number and contact geometry. In the absence of cohesive force, the porosity is nearly invariable with fixed aspect ratio, regardless of the size of the particles. In contrast, as surface energy increases, the porosity increases with decreasing particle size and increasing aspect ratio. The RDF results show that the number of peaks for different aspect ratios changes and show trends similar to the relaxation algorithm, expected for the finer particles. In the case of finer, cohesive particles, the most novel outcome of contact analysis is the existence of single contact, attributed to the formation of a cage structure, which has not been previously reported. The peak position and the width of the contact distributions are affected by higher surface energy because fewer contacts are required to achieve the mechanical equilibrium. Another interesting observation is that higher porosity does not always imply fewer contacts for particles with non-zero aspect ratios and high surface energies. The analysis of the distribution of the contact vector angles is found to better explain increased porosity in spite of higher coordination numbers. The results presented shed light on the packing density and structure, revealing features not easily discerned via experiments, and confirming the important role of the cohesion and aspect ratio in packing.

(Invited) Plasma Activation as a Pretreatment Tool for Low-Temperature Direct Wafer Bonding in Microsystems Technology

Dynamic measurements of interfacial fracture surface energies γ have been carried out during the annealing of pairs of silicon, fused silica and borosilicate glass wafers, resp. Pronounced maxima of the resulting γ(t) curves could be detected in several cases, especially for plasma activated wafer pairs. In the present article the different phases of the bonding process are discussed and an interpretation is given for the formation of the γ(t) maxima. Moreover, influences of plasma activation at atmospheric pressure and at low pressure on the increase in surface energy during annealing are compared. Based on AFM roughness measurements, power spectral densities were determined for two debonded wafer pairs and the influence of the bond strength is discussed here.

Modification of glass surfaces adhesion properties by atmospheric pressure plasma torch

This work is focused in the surface modification of glass samples by an atmospheric pressure plasma torch (APPT), with the aim of properly characterizing every chemical surface modification which could contribute to the assessment of reliable adhesive bonding with polyurethane, silicone, epoxy and cyanoacrylate adhesives.Characterization of glass surfaces both pristine and plasma treated is achieved by surface energy determination through contact angle measurements, Fourier transform infrared spectroscopy in attenuated total multiple reflection mode (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and surface roughness determination. Moreover, the hydrophobic recovery processes suffered by the samples throughout a period of 30 days of storage after APPT treatment is evaluated. Finally, adherence tests are carried out following the ASTM D4541 standard. Results show an increased surface energy with treatment, which partially recovered its initial value with aging. For the adhesive bonding, only the polyurethane shows an improvement on resistance among all the tested adhesive fluids. It is possible to conclude a cleaning, etching and activation effects on the glass surfaces after plasma treatment, with a change in the locus of failure from adhesive to cohesive in some cases, and a reduction in data standard deviation.

Surface pre-treatment for barrier coatings on polyethylene terephthalate

Polymers have favourable properties such as light weight, flexibility and transparency. Consequently, this makes them suitable for food packaging, organic light-emitting diodes and flexible solar cells. Nonetheless, raw plastics do not possess sufficient barrier functionality against oxygen and water vapour, which is of paramount importance for most applications. A widespread solution is to deposit thin silicon oxide layers using plasma processes. However, silicon oxide layers do not always fulfil the requirements concerning adhesion and barrier performance when deposited on films. Thus, plasma pre-treatment is often necessary. To analyse the influence of a plasma-based pre-treatment on barrier performance, different plasma pre-treatments on three reactor setups were applied to a very smooth polyethylene terephthalate film before depositing a silicon oxide barrier layer. In this paper, the influence of oxygen and argon plasma pre-treatments towards the barrier performance is discussed examining the chemical and topological change of the film.It was observed that a short one-to-ten-second plasma treatment can reduce the oxygen transmission rate by a factor of five. The surface chemistry and the surface topography change significantly for these short treatment times, leading to an increased surface energy. The surface roughness rises slowly due to the development of small spots in the nanometre range. For very long treatment times, surface roughness of the order of the barrier layer's thickness results in a complete loss of barrier properties. During plasma pre-treatment, the trade-off between surface activation and roughening of the surface has to be carefully considered.

Improvement of Transparent Metal Top Electrodes for Organic Solar Cells by Introducing a High Surface Energy Seed Layer

AbstractWe present highly transparent and conductive silver thin films in a thermally evaporated dielectric/metal/dielectric (DMD) multilayer architecture as top electrode for efficient small molecule organic solar cells. DMD electrodes are frequently used for optoelectronic devices and exhibit excellent optical and electrical properties. Here, we show that ultrathin seed layers such as calcium, aluminum, and gold of only 1 nm thickness strongly influence the morphology of the subsequently deposited silver layer used as electrode. The wetting of silver on the substrate is significantly improved with increasing surface energy of the seed material resulting in enhanced optical and electrical properties. Typically thermally evaporated silver on a dielectric material forms rough and granular layers which are not closed and not conductive below thicknesses of 10 nm. With gold acting as seed layer, the silver electrode forms a continuous, smooth, conductive layer down to a silver thickness of 3 nm. At 7 nm silver thickness such an electrode exhibits a sheet resistance of 19 Ω/□ and a peak transmittance of 83% at 580 nm wavelength, both superior compared to silver electrodes without seed layer and even to indium tin oxide (ITO). Top‐illuminated solar cells using gold/silver double layer electrodes achieve power conversion efficiencies of 4.7%, which is equal to 4.6% observed in bottom‐illuminated reference devices employing conventional ITO. The top electrodes investigated here exhibit promising properties for semitransparent solar cells or devices fabricated on opaque substrates.

細孔内の液体特性に基づくセメント硬化体の体積変化機構の検討

In this study, the authors investigate the volumetric change of hardened cement paste when the dried specimens under various conditions are soaked in different polar or non-polar liquids. The objective is to comprehend the dominant phenomena to cause the shrinkage of the cement paste based on liquid characteristics. When the oven dried specimens are submerged in various liquids other than water, the shrinkage due to the oven dry is hardly recovered while the shrinkage of the specimens is almost recovered by submerging in water. This could be because the adsorption of the liquids to cement paste is much smaller than that of water and could have little reduction of the solid surface energy of cement paste. The large shrinkage is observed after moist-cured specimens are soaked in polar solvents which are dissolved in water. It could be attributed to the decrease of disjoining pressure and increase of solid surface energy due to the absorption of liquid water and adsorbed water in fine pores and calcium-silicate-hydrate (C-S-H) gel. The shrinkage of partially dried specimens is recovered soon after soaking in both polar and non-polar liquids. It is speculated that the decrease of capillary tension or the increase of disjoining pressure cause the immediate recovery of the shrinkage.本研究では、セメント硬化体に様々な乾燥を与えた後、各種液体に浸漬したときの体積変化を既往の収縮理論に基づき検討し、現象の把握を試みた。水以外の液体はセメント硬化体に対する吸着力が小さいことが浸漬熱より示唆され、絶乾による収縮は水以外の液体に浸漬させてもさほど回復しなかった。セメント硬化体を水中養生後有機溶媒に浸漬させると大きく収縮し、微細空隙内の水分抽出による分離圧の低下及び表面エネルギー増大、一部の結合水の抽出によるC-S-Hゲル自体の収縮を要因に挙げた。また、常温で一定の乾燥を施した後、極性、非極性液体に浸漬させるといずれも収縮が即座に回復し、毛細管張力の低下、分離圧の増加が要因として考えられた。

Partially reduced graphene oxide as a multi-functional sizing agent for carbon fiber composites by electrophoretic deposition

Partially reduced graphene oxide (pRGO) was coated on carbon fibers by an anodic electrophoretic deposition (EPD). Coated-pRGO increased surface energy and wettability of carbon fiber. As a multi-functional sizing agent, pRGO enhanced both mechanical and electrical properties of the carbon fiber composite in spite of introducing a very small amount of less than 0.001 wt%.

Real-time transmission electron microscope observation of nanofriction at a single Ag asperity

The observation of nanoscale deformation in real time is a significant step toward understanding the mechanisms of friction and lubrication. Our experimental setup of a micromachine combined with a transmission electron microscope allowed us to measure the deformation, force and cross-sectional area of a single Ag asperity during shear testing. The experimental results provided insight into one of the parameters that determines the frictional coefficient. Furthermore, we demonstrated that the energy loss associated with a shear fracture event is strongly correlated with the increase in total surface energy of the two surfaces formed here after the fracture of the nanocontact.

Enhanced adhesion of epoxy-bonded steel surfaces using O2/Ar microwave plasma treatment

Steel surfaces have been modified using low pressure microwave plasma to enhance its adhesion with an epoxy adhesive. Optimization of the wettability of the surface was done using contact angle measurements for varying plasma parameters. Maximum wettability (19.9°) was obtained at 1000W microwave power with 20min of treatment time, −50V sample bias and 1.67% O2/Ar gas flow rate ratio. Enhanced wettability of the steel surface was attributed to increased surface roughness and oxide deposition. Using atomic force microscopy, surface roughness was observed to increase from 64.4nm for the untreated surface to 76.7nm for the O2/Ar plasma treated surface. Deposition of oxides on the steel surface was also confirmed by the energy dispersive x-ray spectroscopy. Moreover, the increase in the total surface energy to 53.2mN/m for the O2 plasma treated steel surface supported the enhancement of its wettability, and hence, the adhesion with epoxy. Based on tensile test results, the adhesion strength of epoxy-bonded O2/Ar plasma treated surfaces at optimum settings was increased to 3816.0N, which is significantly higher compared to 3038.3N for the epoxy-bonded untreated surfaces.

DC discharge plasma modification of chitosan/gelatin/PLLA films: Surface properties, chemical structure and cell affinity

The work was aimed to study an effect of direct current discharge on chemical structure, surface properties and cell response to the plasma modified composite films. The film samples were prepared by solvent casting from colloidal solution of the ternary blend of chitosan, gelatin and poly(L,L-lactide), PLLA, obtained by solid-state reactive blending (SSRB), in CH2Cl2 and treated with air plasma at pressure of 10–20Pa and a discharge current of 50mA for 60s. The model film samples casted from the initial components were treated and studied as well. Contact angle of wettability measurements of the films showed that plasma modification led to increase of hydrophilicity and surface energy. Contact angle changes after plasma treatment of chitosan/gelatin/PLLA (CGP) film were more similar to those for the poly(L,L-lactide) film. X-ray photoelectron spectroscopy (XPS) data confirmed that a surface layer of the blend films was enriched with a polyester component. However, study of mouse fibroblast (L929) attachment and growth on the films showed that the CGP film provided an enhanced cell growth compared to this on the poly(L,L-lactide) film. Plasma modification of the polymer films resulted in a substantial increase in fibroblast viability on the plasma treated poly(L,L-lactide) films and to a rather strong decrease of cell growth on the plasma treated CGP and chitosan ones. Thus, plasma surface modification could be proposed as a good tool to control cell response on the material surface.

Non-sticky polyvinylsilazane stamp with high durability for UV-nanoimprint lithography

The feasibility of a sustainable imprint-working stamp made of polyvinylsilazane (PVSZ) is demonstrated. As a control stamp, the Ormostamp, which was typically used as an anti-sticky imprint-working stamp in previous related studies, was used. For the comparing experiments, two types of stamp using Ormostamp and PVSZ were prepared. The working stamp was fabricated by placing a defined amount of UV-curable material on the master stamp and UV curing. For the Ormostamp material, after the cured working stamp was detached from the master stamp, BGL-GZ-83 was coated on the surface of the working stamp and heat treatment was performed. For the PVSZ material, after the cured working stamp was detached from the master stamp, it was subject to heat treatment and hydrolysis treatment in vaporized aqueous ammonia. The nanoimprinting process was repeatedly carried out within polyurethane acrylate (PUA) resin. For the qualitative measurement of increasing surface energy after repeated imprinting, the contact angle of the working stamp made of Ormostamp material and PVSZ was measured before and after the imprinting experiment. According to the contact angle results of the Ormostamp and PVSZ, the PVSZ could be used as a more sustainable imprint-working stamp material than the Ormostamp. Accordingly, a PVSZ working stamp was successfully formed on a glass substrate with an anti-adhesion surface for UV-nanoimprint lithography.

Morphology transformations of pentacene on an UV-patternable polymer insulator and their effect on performance of flexible organic thin-film transistors

This work presents a low temperature with high resolution capability UV-patternable polymer, i.e. mr-UVCur06, for use as a gate insulator in OTFTs, by investigating the morphology transformation of pentacene deposited on the mr-UVCur06. The device structure is polyethylene terephthalate (PET)/indium-tin oxide (ITO)/mr-UVCur06/pentacene/Au (source/drain). In addition to its solution-processable capability, mr-UVCur06 is directly patterned by UV light in a low-temperature process. UV/ozone post-treatment of the patternable mr-UVCur06 can illuminate organic contaminants from its surface and increases surface energy. Experimental results indicate that a high surface energy existing at the mr-UVCur06 surface has produced in a larger ratio of Ithin film phase/Itriclinic bulk phase in pentacene. Then, the distance of pentacene molecular crystal structure, which is arranged in the thin film phase, is shorter than that in triclinic bulk phase. The performance of pentacene-based OTFTs can be enhanced with few contaminants and a high surface energy on the UV-patternable gate insulator. By performing UV/ozone post-treatment on the mr-UVCur06 insulator surface for 60s, the OTFTs demonstrate a mobility, on/off drain current ratio, and VT of 0.34cm2/Vs, 5.5×104, and 2.5V, respectively. Furthermore, the low-temperature photopatternable polymer dielectric paves the way for a relatively easy and low-cost fabrication of an OTFT array without expensive and complicated photolithography and dry etching.Morphology transformations of pentacene on an UV-patternable polymer insulator and their effect on performance of flexible organic thin-film transistors

Treatment surfaces with atomic oxygen excited in dielectric barrier discharge plasma of O2 admixed to N2

This paper describes the increase in surface energy of substrates by their treatment with gas composition generated in plasmas of DBD (Dielectric Barrier Discharge) in O2 admixed with N2. Operating gas dissociation and excitation was occurred in plasmas developed in two types of reactors of capacitively-coupled dielectric barrier configurations: coaxial cylindrical, and flat rectangular. The coaxial cylindrical type comprised an inner cylindrical electrode encapsulated in a ceramic sheath installed coaxially inside a cylindrical ceramic (quartz) tube passing through an annular outer electrode. Components of the flat rectangular type were a flat ceramic tube of a narrow rectangular cross section supplied with two flat electrodes mounted against one another outside of the long parallel walls of this tube. The operating gas, mixture of N2 and O2, was flowing in a completely insulated discharge gap formed between insulated electrodes of the devices with an average velocity of gas inlet of about 7 to 9 m/s. Dielectric barrier discharge plasma was excited in the operating gaps with a bipolar pulse voltage of about 6 kV for 2 ms at 50 kHz repetition rate applied to the electrodes of the coaxial device, and of about 14 kV for 7 ms at 30 kHz repetition rate for the flat linear device. A lifetime of excited to the 2s22p4(1S0) state in DBD plasma and streaming to the surfaces with a gas flow atomic oxygen, responsible presumably for treating surfaces, exceeded 10 ms in certain cases, that simplified its separation from DBD plasma and delivery to substrates. As it was found in particular, surfaces of glass and some of polymers revealed significant enhancement in wettability after treatment.

Effect of nitrogen plasma immersion ion implantation of polyamide-6 on its sliding properties against steel surface

The sliding behaviour of polyamide-6 (PA6) treated by nitrogen plasma immersion ion implantation (N PIII) has not been studied yet, even if PIII is a promising technique for polymer surface modification. The effect of N PIII of PA6 on its sliding properties against low carbon structural steel S235 was studied. The surface changes were characterised by XPS, contact angle measurements and optical microscopy, while alterations in the sliding properties including friction coefficient, wear and temperature close to contact were studied by a pin-on-disc tribometer under dry and variously lubricated conditions. The N-content of the surface layer increased, while those of C and O decreased upon N PIII treatment. The contact angles decreased and the total surface energy and its polar and dispersive components increased significantly. Under dry sliding in the low Pv regime, the friction coefficient of the treated sample started from a value lower than that of the untreated version and the corresponding specific wear rate was also smaller. Under dry sliding, the increased surface energy caused increased adhesion of the treated PA6, associated with the formation of a transfer layer on the steel disc. Water lubrication was more efficient – in accordance with the increased polar component of surface energy – for the treated PA6 than found earlier for PETP. For the treated PA6, a decreased friction was observed upon run-out type lubrication test with gearbox oil, due to increased retention of oil on the treated surface characterised by an increased dispersive component of the surface free energy.