Adhesive Tape Test Research Articles

Mosquito eyes inspired surfaces with robust antireflectivity and superhydrophobicity

Inspired by the compound eyes of the mosquito, the uniform hierarchical structures with antireflectivity and superhydrophobicity has been designed and prepared by spinning technology. Microscale silica spheres and nanoscale colloidal particles were assembled on glass substrate to produce binary structures. To enhance the hydrophobicity, particles were modified by N-(β-aminoethyl)-γ-aminopropylmethylbimethoxy silane (KH-602) before deposition. And annealing process was used to strengthen the mechanical robustness. The resultant structures exhibited low reflections of less than 0.5%, and high static water contact angle (WCA) of larger than 160°. Furthermore, tape adhesion test and washing test showed that the artificial nano-/micro- structures had excellent mechanical robustness. Meanwhile the superhydrophobic surface owned the capacities of self-cleaning ability and chemical stability. We anticipate that these advantages could potentially enhance the performance of optoelectronic devices and help them to survive in terrible environment. Moreover, this self-assembly method is facile, cost effective, and suitable for high-throughput fabrication of binary colloidal arrays.

Study the Effect of Coating Thickness from Silica Nanocomposite Deposited on Poly(Methyl Methacrylate) Sheets via Spray Coating Technique

The development of hard coating based on colloidal silica nanoparticles on polymethyl methacrylate (PMMA) sheet was reported. The colloidal silica was surface-modified with methyltrimethoxysilane (MTMS) and formulated to hard coating solution via sol-gel process. The hard coating solution was applied to PMMA surface by spray deposition technique. Spraying process was carried out from spray nozzle outlet diameter of 0.35 mm and air compress pressure at 0.2 MPa with nozzle to substrate distance at 10 cm. The different coating thicknesses were obtained by adjusting the amount of coating applied. The optimal coating thickness that gives the highest pencil-hardness at 7H and 100% adhesion for adhesion tape test is 10 μm.

A general and facile chemical avenue for the controlled and extreme regulation of water wettability in air and oil wettability under water.

The controlled modulation of both oil (under water) and water (in air) wettability is an emerging approach to develop several functional materials for various prospective applications including oil/water separation, anti-corrosive coatings, underwater robotics, protein crystallization, drug delivery, open microfluidics, water harvesting etc. Here, we report a 'reactive' and covalently cross-linked coating through a facile and robust Michael addition reaction, which is suitable for the controlled and extreme regulation of both water and oil wettability in air and under water respectively. Along with extremes (super-philicity and super-phobicity) of water (in air) and oil (under water) wettability, this single multilayer construction was also able to display special liquid wettability (i.e.; extremely liquid repellent-but with controlled adhesive properties) both in air and under water, after strategic post chemical modifications, again through 1,4-conjugate addition reaction. The super-wetting properties in the materials were able to withstand various physical and chemical insults including adhesive tape test, sand drop test, and exposure to extremes of pH, salt, and surfactant contaminated aqueous media. Moreover, this approach also allowed the decoration of various flexible and rigid substrates (i.e.; wood, Al-foil, synthetic fabric etc.) with various bio-inspired wettability properties including (1) non-adhesive superhydrophobicity (lotus leaf), (2) adhesive superhydrophobicity (rose petal), (3) underwater superoleophobicity (fish scale) etc. This single polymeric coating-which is capable of displaying several bio-inspired interfaces both in air and under water, even after harsh physical/chemical insults-would be useful in various prospective and relevant applications for practical scenarios.

Novel SiO2/H2Ti2O5·H2O-Nanochain Composite with High UV-Visible Photocatalytic Activity for Supertransparent Multifunctional Thin Films.

In the current work, a peroxo titanium complex (PTC) solution was used as a novel water-soluble precursor to fabricate H2Ti2O5·H2O and the SiO2/H2Ti2O5·H2O-nanochain composite at low temperature (90-100 °C). The average width of H2Ti2O5·H2O nanochains is 4.5 ± 1.5 nm. Under full-spectrum irradiation, the Si/Ti-nanochain composite showed good UV-visible light absorption and excellent photocatalytic activity, which is 2.8 times that of P25. In the composite, SiO2 not only contributes to the formation of nanochains and improves the catalytic performance of H2Ti2O5·H2O but also reduces the refractive index of the complex. When coated on transparent organic substrates, the composite thin film exhibited excellent antireflective (as high as 99.3% on PC and 98.9% on PMMA) and self-cleaning properties. Pencil hardness, washing, and tape adhesion tests showed favorable adhesion-to-substrate and mechanical robustness of thin films, which make them extremely attractive for applications as highly transparent and self-cleaning thin films on lenses, photovoltaic cells, and windows of high-rise buildings.

A versatile route to polymer-reinforced, broadband antireflective and superhydrophobic thin films without high-temperature treatment

Broadband high transmittance, good mechanical robustness as well as simple and low temperature fabrication are three important aspects that dictate the practical applications of superhydrophobic thin films, especially on organic substrates. However, it has proved difficult to meet these challenges. In the present work, superhydrophobic thin films were prepared by first dip-coating solid silica nanoparticles, then spray-coating hollow silica nanoparticles, followed by spray-coating mesoporous silica nanosheets & poly(vinyl alcohol) (PVA), and eventually chemical vapor deposition of 1H,1H,2H,2H-perflurooctyltriethoxysilane (POTS) at 90°C. The optimized thin film has a maximum transmittance of 96.0% in the wavelength range of 300–2500nm and a WCA of 164° and a RA of 1°. The thin film also shows good mechanical robustness toward water droplet impact test, sand impact abrasion test and tape adhesion tests, which results from PVA as a binder, the formation of covalent bond between the hydroxyl group of PVA and the ethoxy group of POTS and the chemical inertness of CC, CF bonds of POTS molecules. To our best knowledge, it is the first example where antireflective and superhydrophobic thin films of excellent mechanical robustness were realized at low temperature on organic substrates (PMMA, PC). The current work would provide a promising route to meet the challenges in practical applications simultaneously posed by the requirements of broadband antireflection, good mechanical robustness as well as simple and low temperature fabrication of superhydrophobic thin films.

Neuroprotective efficacy of poly-arginine R18 and NA-1 (TAT-NR2B9c) peptides following transient middle cerebral artery occlusion in the rat

We examined the efficacy of R18 in a transient MCAO model and compared its effectiveness to the well-characterized neuroprotective NA-1 peptide. R18 and NA-1 peptides were administered intravenously (30, 100, 300, 1000nmol/kg), 60min after the onset of 90min of MCAO. Infarct volume, cerebral swelling and functional outcomes (neurological score, adhesive tape and rota-rod) were measured 24h after MCAO. R18 reduced total infarct volume by 35.1% (p=0.008), 24.8% (p=0.059), 12.2% and 9.6% for the respective 1000 to 30nmol/kg doses, while the corresponding doses of NA-1 reduced lesion volume by 26.1% (p=0.047), 16.6%, 16.5% and 7%, respectively. R18 also reduced hemisphere swelling by between 46.1% (1000 and 300nmol/kg; p=0.009) and 24.4% (100nmol/kg; p=0.066), while NA-1 reduced swelling by 25.7% (1000nmol/kg; p=0.054). In addition, several R18 and NA-1 treatment groups displayed a significant improvement in at least one parameter of the adhesive tape test. These results confirm the neuroprotective properties of R18, and suggest that the peptide is a more effective neuroprotective agent than NA-1. This provides strong justification for the continuing development of R18 as a neuroprotective treatment for stroke.

Superhydrophobic surface fabricated by spraying hydrophobic R974 nanoparticles and the drag reduction in water

Abstract Based on the phenomena of the embedding dusts on the surface of fresh paint film, industrialized hydrophobic R974 nanoparticles were used as “dust”, and epoxy resin was used as “paint” to prepare the superhydrophobic film with high bonding strength. The superhydrophobic film was fabricated by spraying the R974-ethanol suspension onto the dip-coated epoxy resin film on glass slide. Because the epoxy resin acted as bonding layer between the R974 nanoparticles film and the glass slide, a combination of high bonding strength and superhydrophobicity was achieved. The superhydrophobic surface was characterized by water contact angle measurements and scanning electron microscopy (SEM). The water contact angle of the R974 coating could reach 154.7°, and the significant differences in the surface morphology of superhydrophobic coating were presented with different R974 concentrations. A flat, fractal-like texture was observed for coatings sprayed with low R974 concentration, and a rough, porous surface for coatings sprayed with high R974 concentration. The adhesion between the R974 coating and epoxy resin was evaluated by the adhesive-tape test. The interaction between fractal-like aggregated R974 with epoxy resin was large enough because of the surface-to-surface contact mode, and the interaction between microparticles of aggregated R974 with the epoxy resin was weak because of the point-to-surface contact mode. By comparing the skin friction drag on normal surface with the prepared superhydrophobic surface, the superhydrophobic coatings achieved a 12% drag reduction in water.

Laser-Direct Writing of Silver Metal Electrodes on Transparent Flexible Substrates with High-Bonding Strength.

We demonstrate a novel approach to rapidly fabricate conductive silver electrodes on transparent flexible substrates with high-bonding strength by laser-direct writing. A new type of silver ink composed of silver nitrate, sodium citrate, and polyvinylpyrrolidone (PVP) was prepared in this work. The role of PVP was elucidated for improving the quality of silver electrodes. Silver nanoparticles and sintered microstructures were simultaneously synthesized and patterned on a substrate using a focused 405 nm continuous wave laser. The writing was completed through the transparent flexible substrate with a programmed 2D scanning sample stage. Silver electrodes fabricated by this approach exhibit a remarkable bonding strength, which can withstand an adhesive tape test at least 50 times. After a 1500 time bending test, the resistance only increased 5.2%. With laser-induced in-situ synthesis, sintering, and simultaneous patterning of silver nanoparticles, this technology is promising for the facile fabrication of conducting electronic devices on flexible substrates.

Plasma modification of substrate with poly(methylhydrosiloxane) for enhancing the interfacial stability of PDMS/PAN composite membrane

This paper described a facile approach to improve the interfacial stability of poly(dimethylsiloxane)/polyacrylonitrile (PDMS/PAN) composite membranes mediated by poly(methylhydrosiloxane) (PMHS). The surface of PAN substrates was modified with PMHS by plasma treatment. The chemical structure and surface morphology of modified PAN substrates were characterized by ATR-IR, XPS, SEM, AFM and CA. The interfacial stability of composite membranes was estimated using the crosshatch tape adhesion test and the swelling experiment. The results showed that the composite membranes supported by modified PAN substrates exhibited high interfacial adhesion and the corresponding PDMS separation layer displayed quite low swelling degrees in toluene and n-heptane, due to the enhanced interfacial interaction. Such enhancement was produced by the stronger mechanical interlocking (increased surface roughness of substrate) and the presence of chemical bonding between PDMS layer and modified PAN substrate. Furthermore, these composite membranes showed good pervaporation performance with a separation factor about 4.2 and a high flux above 9.5kgm−2h−1 in the separation of azeotropic methanol/toluene mixture at 30°C. This work demonstrated that plasma-induced immobilization of PMHS on PAN substrate was an efficient way to improve the interfacial stability of PDMS/PAN composite membrane without sacrifice of its pervaporation performance.

Surface modification of aluminium alloys by atmospheric pressure plasma treatments for enhancement of their adhesion properties

This work deals with surface modification of aluminium alloy AA7075 by two types of atmospheric pressure plasma: dielectric barrier discharge (DBD) and atmospheric pressure plasma jet (APPJ) with the purpose to enhance the adhesion of polyurethane coating on the alloy. The surface characterization was performed by using water contact angle, roughness and surface free energy measurements. Quality of the coating was tested according to the adhesion tape test (ASTM D3359) and evaluated by electrochemical techniques. The aluminium alloy showed great improvement of the surface wettability after plasma treatments. While, the adhesion tape test presented excellent results with perfect adhesion, meaning that both plasma treatments were efficient in improving the adhesion of the polyurethane coating to the AA7075. The Fourier Transform Infrared Spectroscopy (FTIR) results demonstrated that the plasma treatment cleaned the Al alloy surface by removing hydrocarbon contaminations. Both polarization curves and Electrochemical Impedance Spectroscopy (EIS) results showed better characteristics of corrosion resistance for polyurethane-coated AA7075 than untreated coated samples.

Synthesis and characterization of hexafluorozirconic acid powder and its application in nanoceramic coating

Abstract Most of the nanozirconia coating formulations are based on hexafluorozirconic acid solutions that may contain hexafluorosilicic acid indispensably. A new process has been developed to synthesize hexafluorozirconic acid in the powder form which is free from silica as indicated by the absence of Si peak in EDX spectrum. Nano-ceramic coating process is simplified by making up the bath solution using dry H 2 ZrF 6 powder and polyacrylic acid. The powder form makes transportation easier. Hexafluorozirconic acid powder based nano zirconia (PNZ) coat was characterized by FESEM (field emission scanning electron microscopy), EDX (Energy-Dispersive X-ray Spectroscopy), XRD (X-ray diffraction) and XPS (X-ray photoelectron spectroscopy) studies. The PNZ coat formed on mild steel (MS) was characterized by linear polarization (LP) studies and Electrochemical Impedance Spectroscopy (EIS) and also compared with the commercial nano-zirconia coating chemical (Bonderite NT-1) treated mild steel. Polyester epoxy powder coat (PEP) was applied on powder based nano zirconia treated mild steel (PEP/PNZ), and commercially Bonderite NT-1 treated mild steel (PEP/NT). The dry film properties of the organic coat with the nanoceramic base coat were studied by neutral salt spray test, humidity resistance, impact resistance and adhesion tape tests as per ASTM (American Society for Testing and Materials) methods. The corrosion resistance and adhesion of PEP/PNZ coating system are comparable with the performance of PEP coated on the commercial nano zirconia coating solution (NT-1).

Abstract 131: Effect of Fetal Alcohol Exposure on Stroke Severity and Blood Flow in Adult Mice

Background and Purpose: Metabolic and cardiovascular disease in later life may have developmental origins. The present study specifically tested the hypothesis that fetal alcohol exposure (FAE) will persistently influence blood flow in adulthood and result in greater impairment following ischemic stroke. Methods: Timed-pregnant C57Bl/6 female mice (GD12) were intragastrically gavaged with ethanol (3g/kg/bwt) or water twice per day from GD12 through 15. At 3 months of age, FAE and control males and females were subject to high-resolution ultrasound pulsed-wave Doppler imaging to record blood flow in carotid, abdominal, renal and femoral arteries. Blood flow was quantified. Thereafter, mice were subjected to middle cerebral artery occlusion (MCAo) using an intraluminal filament and sacrificed at 24 h post-stroke. Stroke induced brain damage was assessed by behavioral assays (adhesive tape test), neurological score and infarct volume. Results: Blood flow measurements indicated that fetal alcohol exposure increased acceleration in renal lobar arteries of ethanol exposed females (P<0.003), indicating that alcohol exposure may lead to impairment vascular tone and early signs of hypertension in end organs like kidney. In animals subject to MCAo, FAE adults exhibited greater neurological deficits at 24h post-stroke, as determined by their higher scores on a combination of different parameters of motor impairment and behavioral measures (neurologic score) compared to controls (P<0.0004). Sensorimotor deficits assessed by sticky tape test also showed that fetal alcohol exposed animals were severely affected (p<0.05) indicating that developmental alcohol exposure can impair adaptation in adult brain to an acute neural damage. There is also a significant correlation between the neurological scores and infarct volume in FAE females (p<0.05) but not FAE males, suggesting sex differences in response to FAE modify the relationship between stroke and outcomes. Conclusions: Our findings support a hypothesis that fetal alcohol exposure has long lasting and sexually dimorphic effects on adult health, resulting in impaired renal blood flow and poor stroke outcomes.

Comparative study on polyester epoxy powder coat and amide cured epoxy liquid paint over nano-zirconia treated mild steel

Abstract The effect of commercial nano-sized zirconium hydrous oxide (NT) coating of mild steel (MS) on corrosion resistance and its adhesion to polyester epoxy powder coat (PEP) and amide cured epoxy white finish paint (EPF) was investigated. The corrosion rate of untreated and NT treated MS was evaluated from linear potential parameters such as corrosion current, corrosion potential and Tafel plots. NT base coat was characterized by EIS (electrochemical impedance spectroscopy), FESEM (field emission scanning electron microscopy), EDX (energy-dispersive X-ray spectroscopy), AFM (atomic force microscopy), XRD (X-ray diffraction) and XPS (X-ray photoelectron spectroscopy) studies. The dry film properties of the top coats of PEP and EPF were compared by neutral salt spray test, humidity resistance, impact resistance and adhesion tape tests as per ASTM (American Society for Testing and Materials) methods. The mechanism of zirconia deposition on the hydroxyl sites of the mild steel surface was evident from the results of XPS. The corrosion resistance and adhesion of PEP/NT coating system were found to be superior to that of EPF/NT system from salt spray resistance test and cross hatch test by adhesive tape. The superior corrosion resistance of EPF/NT to EPF/MS shows the efficacy of the NT conversion coating on MS.

Porous, High Capacity Coatings for Solid Phase Microextraction by Sputtering.

We describe a new process for preparing porous solid phase microextraction (SPME) coatings by the sputtering of silicon onto silica fibers. The microstructure of these coatings is a function of the substrate geometry and mean free path of the silicon atoms, and the coating thickness is controlled by the sputtering time. Sputtered silicon structures on silica fibers were treated with piranha solution (a mixture of concd H2SO4 and 30% H2O2) to increase the concentration of silanol groups on their surfaces, and the nanostructures were silanized with octadecyldimethylmethoxysilane in the gas phase. The attachment of this hydrophobic ligand was confirmed by X-ray photoelectron spectroscopy and contact angle goniometry on model, planar silicon substrates. Sputtered silicon coatings adhered strongly to their surfaces, as they were able to pass the Scotch tape adhesion test. The extraction time and temperature for headspace extraction of mixtures of alkanes and alcohols on the sputtered fibers were optimized (5 min and 40 °C), and the extraction performances of SPME fibers with 1.0 or 2.0 μm of sputtered silicon were compared to those from a commercial 7 μm poly(dimethylsiloxane) (PDMS) fiber. For mixtures of alcohols, aldehydes, amines, and esters, the 2.0 μm sputtered silicon fiber yielded signals that were 3-9, 3-5, 2.5-4.5, and 1.5-2 times higher, respectively, than those of the commercial fiber. For the heavier alkanes (undecane-hexadecane), the 2.0 μm sputtered fiber yielded signals that were approximately 1.0-1.5 times higher than the commercial fiber. The sputtered fibers extracted low molecular weight analytes that were not detectable with the commercial fiber. The selectivity of the sputtered fibers appears to favor analytes that have both a hydrophobic component and hydrogen-bonding capabilities. No detectable carryover between runs was noted for the sputtered fibers. The repeatability (RSD%) for a fiber (n = 3) was less than 10% for all analytes tested, and the between-fiber reproducibility (n = 3) was 0-15%, generally 5-10%, for all analytes tested. The repeatabilities of our sputtered fibers and the commercial 7 μm PDMS fiber are essentially the same. Fibers could be used for at least 300 extractions without loss of performance. More than 50 compounds were identified in a gas chromatography-mass spectrometry headspace analysis of a real world botanical sample with the 2.0 μm fiber.

Bone marrow mesenchymal stem cell transplantation enhances angiogenesis and functional recovery after cerebral ischemia in rats

Objective To investigate the effect of bone marrow mesenchymal stem cells(BMSCs) transplantation on angiogenesis and functional recovery after focal cerebral ischemia in rats. Methods BMSCs were isolated and cultured using the whole bone marrow adherent method, and conducted phenotypic identification using flow cytometry analysis of surface positive antigen of CD29, CD90 and the negative antigen of CD34, CD45.Rats were subjected to middle cerebral artery occlusion (MCAO) for 90 minutes, and divided into three groups randomly, the sham group, model group and BMSCs group.24 hours after cerebral ischemia, rats were injected with 1ml BMSCs solution (1×106 cells/ml) or PBS via the tail vein. The modified neurological severity score( mNSS ) test, the corner test and the adhesive tape test were used to evaluate sensorimotor function on the 1, 7, 14 and 28 days after ischemia. Infarcted volume was detected by toluidine blue staining, and the numbers of vWF positive microvessels and vascular endothelial growth factor (VEGF) positive cells in the ischemic boundary were determined by immunofluorescence. Results By flow cytometric analysis, the cell phenotype of passage 3 BMSCs showed that CD29, CD90, CD34 and CD45 were 98.3%, 97.4%, 0.2% and 4.8%, respectively . Compared with the model group, BMSCs significantly reduced the score of mNSS(P<0.01), the number of right turn of corner test(P<0.05), latency of removal adhesive tape(P<0.05) and the infarcted volume (P<0.01). The numbers of vWF positive vessels and the VEGF positive cells were (42.97±8.64)/mm2 and (54.83±10.66)/mm2 at the boundary zone in model group 14 days after ischemia, respectively. BMSCs significantly increased the numbers of vWF positive vessels ((69.43±7.29)/mm2) and VEGF positive cells ((78.70±6.16)/mm2 , P<0.01). Conclusion BMSCs can improve the functions of cerebral lesions after cerebral ischemia, which may be associated with the enhanced angiogenesis and VEGF expression in the ischemic boundary. Key words: Bone marrow mesenchymal stem cells; Cerebral ischemia; Angiogenesis; Vascular endothelial growth factor

Mechanically robust superhydrophobic and superoleophobic coatings derived by sol–gel method

Mechanically robust coatings that display both superhydrophobic and superoleophobic behavior are of great interest for a wide range of applications including sports facilities, automobile and aircraft, solar panels, and wind turbine blades. In this study, a novel method of combining both low and high surface energy SiO2 nanoparticles was employed to prepare superhydrophobic and superoleophobic coating by sol–gel method. The hydrophobicity and oleophobicity of the coatings were analyzed by various liquid droplets with surface energy ranging from 72.4 to 29.5mJ/m2. Pencil scratch test, cross-cut tape adhesion test, nano-indentation, and PosiTest Pull-Off adhesion test were carried out for the coating mechanical properties. Tuning of surface topology was carried out by controlling molar ratio of low and high surface energy SiO2 nanoparticles. It is observed that with the molar ratio at 2:4 between the low and high surface energy SiO2 nanoparticles, the coating gives rise to the best superoleophobicity and mechanical properties. Such coatings hold good promise for self-cleaning and anti-icing applications under mechanically erosive/abrasive environment.

Polyurethane paint adhesion improvement on aluminium alloy treated by plasma jet and dielectric barrier discharge

The effect of atmospheric pressure plasma treatment on the adhesion between a protective coating and AA1100 alloy was investigated. Two plasma sources were used for surface modifications: atmospheric pressure plasma jet and dielectric barrier discharge. The surface roughness and water contact angle measurements were conducted in order to evaluate the changes on the aluminium surface after plasma processing. The paint coating was tested using the adhesion tape test (ASTM D3359). A significant improvement of surface wettability and adhesion was obtained after plasma treatments.

Recycling of lithium-ion batteries: a novel method to separate coating and foil of electrodes

Lithium-ion batteries will play a crucial role in the development of mobile consumer devices, stationary energy storage systems, and electric mobility. The growth in these fields will bring about a surge in the lithium-ion battery market. This leads experts to agree that more effective recycling processes are needed in conjunction with the recycling of lithium. This calls for an entirely revolutionary recycling process which we here have attempted to develop.Our approach uses thermal decomposition of the polyvinylidene fluoride binder to lessen the cohesion of coated active material particles and weaken the adhesion between coating and foil. Then, an air-jet-separator is able to detach the coating powder from the current collector foils while stressing remaining particulate agglomerates. This separation process named ANVIIL (Adhesion Neutralization via Incineration and Impact Liberation) was tested on a laboratory scale with electrode rejects. We compared this to the widely used mechanical recycling process that utilizes a cutting mill to separate the current collector and coating. Intermediates and products were characterized using thermogravimetric analysis, tape adhesion tests, atomic absorption spectroscopy, particle size analysis, and gravimetric sieve analysis. We found that 97.1% w/w of the electrode coating can be regained with aluminum impurities of only 0.1% w/w, 30 times purer than the comparative process. This demonstrates a more effective recycling process than is currently available that also enables the recapture of lithium from the electrode coating.

Enhancement of bioactivity on medical polymer surface using high power impulse magnetron sputtered titanium dioxide film.

This study utilizes a novel technique, high power impulse magnetron sputtering (HIPIMS), which provides a higher ionization rate and ion bombardment energy than direct current magnetron sputtering (DCMS), to deposit high osteoblast compatible titanium dioxide (TiO2) coatings with anatase (A-TiO2) and rutile (R-TiO2) phases onto the biomedical polyetheretherketone (PEEK) polymer substrates at low temperature. The adhesions of TiO2 coatings that were fabricated using HIPIMS and DCMS were compared. The in vitro biocompatibility of these coatings was confirmed. The results reveal that HIPIMS can be used to prepare crystallinic columnar A-TiO2 and R-TiO2 coatings on PEEK substrate if the ratio of oxygen to argon is properly controlled. According to a tape adhesion test, the HIPIMS-TiO2 coatings had an adhesion grade of 5B even after they were immersed in simulated body fluid (SBF) environments for 28days. Scratch tests proved that HIPIMS-TiO2 coatings undergo cohesive failure. These results demonstrate that the adhesive force between HIPIMS-TiO2 coating/PEEK is stronger than that between DCMS-TiO2 coating/PEEK. After a long period (28days) of immersion in SBF, a bone-like crystallinic hydroxyapatite layer with a corresponding Ca/P stoichiometry was formed on both HIPIMS-TiO2. The osteoblast compatibility of HIPIMS-TiO2 exceeded that of the bare PEEK substrate. It is also noticeable that the R-TiO2 performed better in vitro than the A-TiO2 due to the formation of many negatively charged hydroxyl groups (-OH(-)) groups on R-TiO2 (110) surface. In summary, the HIPIMS-TiO2 coatings satisfied the requirements for osseointegration, suggesting the possibility of using HIPIMS to modify the PEEK surface with TiO2 for spinal implants.

Enhancement of stability and photoactivity of TiO2 coatings on annular glass reactors to remove emerging pollutants from waters

TiO2 coatings of highly photoactive lab-made titania were prepared on the outer wall of the inner tube of a glass tubular reactor by dip-coating method. The effect of decreasing the size of the aggregates to improve adhesion and photoactivity of the coatings to degrade phenol, diclofenac and isoproturon was also investigated. Chemical disaggregation of the TiO2 particles resulted in a lower aggregate size, between 0.1 and 1μm, than mechanical disaggregation, between 1 and 10μm. The results of the adhesion tape test showed that either milling of aggregate material with a planetary mill or chemical stabilization of the particles were necessary to obtain TiO2 coatings on glass tube with acceptable quality to be used in water treatment applications. SEM images showed that coatings prepared after milling the TiO2 suspension were more homogeneous without surface aggregates. The degree of adhesion of the coatings after increasing the roughness of the support by abrasive blasting was also evaluated. Adhesion to the substrate was slightly lower when using the modified support. The photoactivity results showed that the coatings prepared after wet milling of catalyst during 30min and after chemical disaggregation were more efficient in terms of degradation and mineralization when using phenol as model molecule. Subsequent studies with two emerging pollutants, diclofenac and isoproturon, also showed enhanced efficiency of these coatings. The reusability of the TiO2 coatings was also evaluated and a promising photocatalytic performance was observed with a very low variation of the decay rate after five consecutive usages.