Cross-cut Tape Research Articles

Biocompatible and hydrophilic copper-complexed polyvinyl alcohol coating for antifogging surfaces

Visibility is decreased when fog accumulates on the clear surface of optical devices. It is quite desirable to design the surface with antifogging properties. The current study used a dip coating process to prepare copper-incorporated polyvinyl alcohol (PVA) hydrophilic coating on the hydroxylated glass substrate. The formation of the PVA-Cu complex by the hydroxyl group was determined by FTIR and XPS methods. The surface morphology, adhesion test, wettability behavior, and cytotoxicity were investigated by SEM, cross-cut tape, contact angle measurement, and MTT experiment. By varying the CuCl2 concentration (0.0125–0.0625 M), the durability and adhesion of the coating were improved, as evidenced by its minimal mass loss and water uptake. The optimum coating condition showed a thickness of about 24.0 ± 0.7 μm and a good optical transmittance of over 90 %. Below 0.0375 M, the coating stability and water resistance could not be achieved due to the weak complexation of Cu with the PVA coating. In contrast, the PVA-Cu3 coating (0.0375 M, Cu2+ ions) was identified as an optimized condition for improved antifogging performance due to the effective complexation of Cu with the PVA matrix while maintaining the hydrophilicity and wettability behavior. Furthermore, no cytotoxicity was observed by L929 cell lines in response to the prepared coating. The current study results revealed that the adhesive, hydrophilic PVA-Cux coating with a contact angle of less than 62° might demonstrate strong antifogging properties and find its usage for endoscopic applications.

Exploring the potential of Gigantochloa levis and Gigantochloa scortechinii bamboo species for plybamboo production

Gigantochloa levis and G. scortechinii bamboo species were evaluated as material for plybamboo production. Plybamboo was composed of three layers with 12 mm thickness and used phenol formaldehyde (PF) as their binder. Representative samples were cut and tested for bonding, physical, mechanical, and finishing properties. Results indicated that G. levis plybamboo exhibited higher bending strength property compared to G. scortechinii plybamboo, as indicated by its higher modulus of rupture (121 N/mm2) and modulus of elasticity (16300 N/mm2). The G. levis plybamboo also displayed higher bond shear strength and was dimensionally stable compared to G. scortechinii plybamboo. The finishing properties revealed that all coatings performed well in the cross-cut tape and pull-off tests. Notably, plybamboo from both bamboo species showed excellent coating film adhesion. Based on minimum standard requirement, results revealed that both bamboo species were suitable to be used in plybamboo production for general use. The findings showed that those species are valuable renewable natural resources for plybamboo production and had potential to be utilized as a substitute for wood in board production.

Design and realization of versatile durable fluorine-free anti-corrosive coating with robust superhydrophobicity

Bio-inspired superhydrophobic coatings are of increasing interest in marine corrosion protection due to their superior barrier and shielding effects. However, some difficult problems like weak mechanical strength, the use of costly and toxic reagents, and intricate preparation processes have long hindered the practical application of the superhydrophobic coatings. Herein, a durable, self-cleaning and anti-corrosion superhydrophobic coating based on epoxy resin matrix was successfully fabricated, avoiding the use of fluorine materials. The prepared coating possessed excellent superhydrophobicity and was applicable to a variety of substrates, which was ascribed to the effect of modified kaolin particles on lowering surface energy. Through SEM and LSCM, the superhydrophobic coatings manifested the morphology feature of "hills+mountain", which could store air to reduce solid-liquid contact. The prepared coating had been proven to have greater impedance modulus and charge transfer resistance by EIS test, and displayed outstanding durability in salt spray environment compared with pure epoxy coating. In addition, the sandpaper abrasion, standard cross-cut tape and self-cleaning tests indicated that the superhydrophobic coatings satisfied robust mechanical stability and excellent resistance to contaminants, laying the foundation for the application of superhydrophobic coating in practical environment.

Revealing the mechanism of interfacial adhesion enhancement between the SiO2 film and the GaAs substrate via plasma pre-treatments

The formation mechanism of a highly adherent silicon dioxide (SiO2) film on gallium arsenide (GaAs) substrate by plasma enhanced chemical vapor deposition (PECVD) is proposed. Ar, N2, and NH3 were used as pre-treatment gas to improve the interfacial adhesion. The interfacial adhesion was measured by the cross-cut tape test. By the measurement of spectroscopic ellipsometry and x-ray photoelectron spectroscopy (XPS), it is revealed that nitrogen plasma pre-treatment had formed a very thin GaN transition layer on the surface, which was responsible for the improvement of interfacial adhesion. XPS depth-profiling further confirmed various pre-treatment gases generate plasma mixtures and form thin film layers with different compositions on the GaAs surface. These layers have a significant impact on the adhesion of the subsequently prepared SiO2 film. The primary mechanism for improving interfacial adhesion is the renovation of the substrate composition via plasma pre-treatment by PECVD, which forms a transition layer of nitrides that eliminates the negative effects of oxides on adhesion. This study reveals the mechanism of interfacial adhesion enhancement between SiO2 film and GaAs substrate, which is of significant importance in fabricating high-performance and reliable semiconductor devices.

Hybrid inorganic–organic coatings enhancing glass corrosion resistance

This work aims to prepare a functional hybrid organic–inorganic coating on glass using the sol–gel process. The sol–gel coatings are commonly used for changing and/or enhancing optical, chemical and mechanical properties of the substrate glass. The coatings prepared in this work should exhibit high transmittance and good chemical resistance, whereof should be achieved by the combination of default precursor tetraethoxysilane (TEOS) and various functionalized silicon alkoxides 3-(trimethoxysilyl)propyl methacrylate (MEMO) and isobutyl(trimethoxy)silane (IBTMS). Sols were applied on substrate glass via the dip-coating method at different withdrawal speeds. Coatings were dried 1 h at 200 °C in ambient atmosphere. Assessment of transmittance was done by UV-Vis spectrophotometry, chemical resistance was observed by accelerated weathering tests in a humidity chamber, mechanical properties were evaluated with the means of standardized pencil hardness test and cross-cut tape test, and moreover analysis of abrasion resistance was done by model test. The most efficient functionalization was combination of 1% IBTMS + 1% MEMO and functionalization with MEMO up to 2% alone. These coatings showed good resistance against damp heat, they can withstand certain loads of abrasion and concurrently still exhibit high transmittance in the visible spectrum.Graphical

Flexible and gradually bonded metal organic framework coatings for atomic oxygen protection of polyimide films

Rapid development of coatings with atomic oxygen (AO) resistance, which benefit long-duration exploration mission in low earth orbit (LEO), poses a challenging requirement on flexible coatings with excellent bonding property. Metal organic framework (MOF) has abundant sites and organic–inorganic hybrid chemical composition, which displays potential in increasing AO resistance, flexibility and bonding property simultaneously. Here, we combined surface modification and spin-coating to prepare MIL-53(Al) (a kind of materials of Lavashir skeleton) coated polyimide (PI) thin film exhibiting excellent flexibility, bonding property and AO resistance, which had no cracks after bending 1000 times, had no peeling off and had only 12% erosion yield compared with pristine PI, verified by the bend test, cross-cut tape test and AO exposure experiment respectively. Also, the mechanism of homogeneous film formation was explained, in which MIL-53(Al) seed layer provided binding force between coating and substrate, and the microstructural transformation caused by breathing effect and negative linear compressibility (NLC) prevented the occurrence of coating cracking. This work extends the application range of MIL-53(Al), optimizes the application of MOFs film formation, and offers a new idea to protect the spacecrafts in LEO.

Corrosion-resistant coating on AZ91D magnesium alloy based on one-step hydrothermal

ABSTRACT Magnesium alloys are widely used due to their excellent properties, but their corrosion resistance is limited by their high chemical activity. This paper proposes a one-step hydrothermal method with a relatively short reaction time and simple experimental steps for synthesising magnesium alloy coatings with good corrosion protection properties. The surface morphology, chemical composition and corrosion resistance of the in situ generated coatings were investigated using measurements such as field emission scanning electron microscopy (SEM), adhesion cross-cut tape (ACCT) test, X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), electrochemistry and immersion test, the results revealed that the corrosion current density (Icorr) of the coatings decreased by approximately four orders of magnitude and had good corrosion resistance.

High-performance printed electrode with rapid fabrication based on UV and IPL light processes without thermal treatment

We developed flexible and ultraviolet (UV)-curable electrodes with improved electrical conductivity using two light processes. Existing microparticle electrodes have poor durability. In this study, we improved electrode durability by facilitating UV light transmission using nanosilver particles and increased electrical conductivity using the photonic sintering process as a posttreatment process. The formulation of the UV-curable nanosilver paste developed this way had no problem in the cross-cut tape test and showed excellent pencil hardness (>3H). Furthermore, the electrical resistivity was 2.76 × 10−5 Ω·cm, and the resistance change rate was <1 % even after 50,000 times of repetitive tests with a 3-mm radius of curvature. When twelve electrode patterns with LED installation and bent were manufactured, we confirmed that there was no change in brightness. Finally, as polyethylene terephtalate, a low-temperature substrate, was not damaged even after the process was completed, the paste and process showed sufficient performance even in the low-temperature process.

One-step spraying achieved superhydrophobic fluoroSiO2@epoxy coating with corrosion-wear resistance and anti-wetting stability

Biomimetic superhydrophobic materials with reduced liquid-solid interfacial contact, non-wetting and water repelling properties exhibits promising multi-functional application potentials, but hindered by poor mechanical stability, complex preparation process, expensive reagents, strict equipment requirements, and ecologically environmental pollution. Herein, we developed a corrosion resistant and mechanically stable superhydrophobic coating based on modified fluoroSiO2 and epoxy resin via a facile one-step spray-coating technique. The electrochemical impendence spectroscopy (EIS) and potentiodynamic polarization results confirmed the remarkably enhanced corrosion resistance of the superhydrophobic fluoroSiO2 @epoxy coating with a corrosion inhibition efficiency of 99.86%. More importantly, the created superhydrophobic fluoroSiO2 @epoxy coating maintains its non-wetting Cassie-Baxter state, self-cleaning and anti-fouling properties after continuously tape-peeling cycles, abrasion cycles, self-cleaning cycles and standard cross-cut tape tests, verifying a strengthened coating/substrate binding force and wear resistance. The easy adaptability and scalability of the spray-coating approach and mechanical robustness of the designed superhydrophobic fluoroSiO2 @epoxy coating will greatly expand its real-world application fields.

Electron beam-cured linseed oil - Diacrylate blends as a green alternative to overprint varnishes: Monitoring curing efficiency and surface coating properties

Electron beam (EB)-cured unsaturated vegetable oil and diacrylate was formulated as an alternative and green overprint varnish (OPV) for coatings in a finishing process. Linseed oil (LO) was applied with tripropylene glycol diacrylate (TPGDA) in different ratios to obtain EB-curable LO-based OPV (eLOPV). The eLOPV were irradiated by EB for curing using various absorbed doses of 10–100 kGy. Change of the functional groups, chemical structure and transition temperature of EB-cured eLOPV were characterized by FTIR, 13C-NMR and DSC. The curing efficacy was assessed by measuring conversion, gel fraction, swelling degree and by characterizing surface properties using solvent rub-test and cross-cut tape test methods. The EB-cured eLOPV exhibited great surface adhesion on substrates. The surface morphologies of the EB-cured eLOPV on papers and plywood sheets were observed by SEM. The results indicate that the eLOPV (LO-TPGDA blend 40: 60 w/w) was completely cured using EB at 30 kGy. Th optical properties were observed via yellowness and whiteness indexes according to ASTM E 313. Color difference and gloss value were measured using colorimeter and gloss meter, respectively. The eLOPV provide good surface qualities, i.e, good surface adhesion, low yellowness, homogeneous cured surface, high gloss value, and hydrophobic surface. Aiming at well-optimized formula and effective EB-curing process, the synthetic chemical can be reduced at least 50% w/w by using vegetable oil without photo-initiator. The utilization of LO and EB curing technology is a promising strategy for bio-/green-coatings approach.

Bio-based polyurethane coating synthesized from modified castor oil - applicable in base coat of automobile paint

The current study reports the epoxidation of castor oil (CO) by using hydrogen peroxide as catalyst and formic acid as oxidizing agent. Subsequently bio based polyurethane based base coat was synthesized by using epoxidised castor oil (ECO) as polyol, Isophorone diisocyanate (IPDI) as curing agent and dibutylin dilaurate (DBTDL) as catalyst. The paint formulation with OH:NCO ratio 1:1.2 was optimized. An independent study was carried out employing the mechanical test like cross-cut tape test was carried out to evaluate th paint properties. Morphological and structural studies like FTIR, SEM, HNMR were carried out with the paint formulation. Thermal property studies like TGA, DSC were carried out with the paint. Gloss, weather resistance of the paint was evaluated.

Improving the Efficiency, Stability, and Adhesion of Perovskite Solar Cells Using Nanogel Additive Engineering.

Additive engineering has been applied widely to improve the efficiency and/or stability of perovskite solar cells (PSCs). Most additives used to date are difficult to locate within PSCs as they are small molecules or linear polymers. In this work, we introduce, for the first time, carboxylic acid-functionalized nanogels (NGs) as additives for PSCs. NGs are swellable sub-100 nm gel particles. The NGs consist of poly(2-(2-methoxyethoxy) ethyl methacrylate)-co-methacrylic acid-co-ethylenegylcol dimethacrylate (PMEO2MA-MAA-EGD) particles prepared by a scalable synthesis, which have a diameter of 40 nm. They are visualized in the perovskite films using SEM and are located at the grain boundaries. X-ray photoelectron and FTIR spectroscopy reveal that the NGs coordinate with Pb2+ via the -COOH groups. Including the NGs within the PSCs increased the grain size, decreased nonradiative recombination, and increased the power conversion efficiency (PCE) to 20.20%. The NGs also greatly increase perovskite stability to ambient storage, elevated temperature, and humidity. The best system maintained more than 80% of its original PCE after 180 days of storage under ambient conditions. Tensile cross-cut tape adhesion tests are used to assess perovskite film mechanical integrity. The NGs increased both the adhesion of the perovskite to the substrate and the mechanical stability. This study demonstrates that NGs are an attractive alternative to molecularly dispersed additives for providing performance benefits to PSCs. Our study indicates that the NGs act as a passivator, stabilizer, cross-linker, and adhesion promoter.

Adhesion Strength of Hydroxyapatite Coating on Titanium Alloy (Ti-6Al-4V ELI) for Biomedical Application

Implantation using titanium Ti-6Al-4V ELI still has disadvantages, in particular, low osseointegration cause of less bioactive of the material. Hydroxyapatite was then applied as a coating material to increase the bioactivity and the osseonintegration as well. The Ti-6AL-4V ELI samples were coated with the hydroxyapatite using the electrophoretic deposition (EPD) method, with voltage variations of 5, 8 and 11 volts for 5 minutes and variations in deposition time for 5,8 and 11 minutes with voltage of 8 volt. Surface properties (coarseness, coating mass, thickness, and surface coverage) were then determined by using related equipments. Adhesion strength the HA layer was tested a cross-cut test method. The results showed that the EPD could be used properly to coat the Ti-6Al-4V ELI material with hydroxyapatite. Voltage and deposition time influence coating layer properties that is related to adhesion bonding of the layer on the metal surface. Applying the voltage of 8 volt for 5 minutes resulted in optimal surface properties with coating roughness of hydroxyapatite layer (Ra) as much as 0.88. The removed area after the cross-cut tape test is 2.25%, which means adhesion strength between the coating layer and the subtrate is high enough. A relatively high hydroxyapatite mass (0.3 mg), is covering the material surface with a surface coverage of 82.1%, and the average coating thickness is 73.3 μm. Such kind of coating layer characteristics could improve bioactivity, biocompatibility and thus enhancing osseonintegration capacity of prosthetic medical implants.

Effect of Particle Size on Adhesion Strength of Bovine Hydroxyapatite Layer on Ti-12Cr Coated by using Electrophoretic Deposition (EPD) Method

Hydroxyapatite (HA) extracted from bovine bones (called as natural HA) was used to coat a relatively new developed titanium alloy, Ti-12Cr, by using the electrophoretic deposition (EPD) method. This is to improve biocompatibility and bioactivity properties of the material to achieve optimal osseointegration in orthopaedic implant applications. There are three particle sizes of the natural HA used in this study (25 μm, 63 μm, and 125 μm) which aims to determine their effect on morphology, structure, and the strength of the resulting coating adhesion. The coating process was carried out at a voltage of 5 Volt for 5 minutes. The resulting layer morphologies and surface coverage were observed using an optical microscope. The increase in sample mass was measured using digital scales to determine the amount of the particles deposition. The coating thickness was measured using coating thickness gauges, and adhesion strength the coating layer was measured by using the cross-cut tape test method. The results of this study indicate that the HA particle size influences significantly on the quality of the coating produced after the EPD process. It is found that the coated Ti-12Cr with a small particle size has better surface properties as compared to the coarse one. Therefore, small size natural HA particles seemmore suitablefor implant applications.

Effect of Silica Size and Content on Superamphiphobic Properties of Silica-Fluoropolymer Core-Shell Coatings.

We present a facile approach to fabricate superamphiphobic surfaces by spray coating silica-fluoropolymer core-shell particles without substrate pretreatment with an additional binder resin. A series of SiO2@poly(1H,1H,2H,2H-heptadecafluorodecyl methacrylate) (SiO2@PFMA) core-shell particles with core particles of different sizes were prepared via thiol-lactam initiated radical polymerization (TLIRP). The surface of each SiO2 particle with an average particle size of 12, 80, 150, and 350 nm was modified with (3-mercaptopropyl) trimethoxysilane and used as a seed for TLIRP. The SiO2@PFMA particles with various SiO2 sizes and contents were coated on aluminum substrates by a spray gun and then thermally treated to form a stable, rough composite layer. During the spray coating, the core-shell particles were aggregated by rapid evaporation of the solvent and then irregularly adhered to the substrate resulting in hierarchical structures. In the case of SiO2@PFMAs with low SiO2 contents, the roughness created mainly by the polymer shell disappeared during heat treatment. However, the substrates coated with SiO2@PFMAs with high SiO2 contents maintained the roughness even after heat treatment. The core-shell particles prepared with 12 nm SiO2 formed a stable superamphiphobic surface. The water/hexadecane contact and sliding angles on an aluminum plate coated with SiO2@PFMA, prepared using 12 nm silica at 46 wt% silica content (12 nm-SiO2(46)@PFMA), were 178.5°/159.2° and 1°/7°, respectively. The cross-cut tape test showed that adhesion between the 12nm-SiO2(46)@PFMA and the aluminum substrate was classified as 5B. A glass surface spray-coated with the core-shell composite particles exhibited transparent superhydrophobicity and translucent superamphiphobicity by controlling the concentration of the coating solution.

Microstructure of Electrodeposited Nickel: Role of Additives

Micro–nanoscale surface microstructure of electrodeposited nickel on AISI 430 substrate from sulfamate bath with ionic and nonionic additives was investigated. 0.69 × 10−4-2.08 × 10−4 M sodium dodecyl sulfate (SDS) and 0.5-4.0 M sodium chloride (NaCl) were used as ionic additives. 0.5-4.0 M ethanol and 1-propanol were used as nonionic additives. Ethanol, propanol, and NaCl promote evolution of nickel micro–nanocones/pyramids. Concentration of these additives, especially NaCl, plays a significant role to modify nickel microstructure. Adhesion of deposited nickel with the substrate, determined by crosscut tape test, is excellent for SDS, ethanol, and propanol additive regardless of their concentration. NaCl degrades the adhesion resulting 100% removal of deposited nickel for 4.0M additive in sulfamate bath. Nickel coating without additive and 1.39 × 10−4 M SDS additive corrode at the same rate (1.08 × 10−2 mm/year), while the other additives increase the corrosion rate.

Robust and superomniphobic core-shell SiO2@poly(1H,1H,2H,2H-heptadecafluorodecyl methacrylate-co-methyl methacrylate) coating materials synthesized by thiol lactam initiated radical polymerization

Superomniphobic SiO2@poly(1H,1H,2H,2H-heptadecafluorodecyl methacrylate-co-methyl methacrylate) (SiO2@poly(FMA-co-MMA)) core-shell spheres were synthesized via a thiol lactam initiated radical polymerization (TLIRP). SiO2 and poly(FMA-co-MMA)s were used as they imparted both surface roughness and low surface energy for superhydrophobic surfaces. SiO2 particles were synthesized using the Stöber method, and their surface was subsequently modified with (3-mercaptopropyl) trimethoxysilane and used as seeds for polymerization in the presence of γ-butyrolactam. The CH2 peaks (4.26 and 2.56 ppm) from poly(FMA) and the CH3 peak (3.53 ppm) from poly(MMA) were observed in the 1H-NMR spectra, indicating successful preparation of SiO2@poly(FMA-co-MMA) by TLIRP. The maximum water and hexadecane contact angles of an aluminum plate coated with particles were 164.0° and 130.1°, respectively. The cross-cut tape test of the coated aluminum plate showed that adhesion between the coating material and the substrate was classified as 5B, without damage. Furthermore, the substrate maintained superhydrophobicity after 40 cycles of tape peeling, although the water contact angle slightly decreased (163.1°) and the sliding angle slightly increased (2° to 3°). The mechanical strength of the coated aluminum plate was enhanced by heat treatment above the Tg of SiO2@poly(FMA-co-MMA)s. The SiO2 content of SiO2@poly(FMA-co-MMA)s affected the wettability of the coating surface due to roughness generated by the core SiO2 particles.

PDMS-Parylene Adhesion Improvement via Ceramic Interlayers to Strengthen the Encapsulation of Active Neural Implants.

Parylene-C has been used as a substrate and encapsulation material for many implantable medical devices. However, to ensure the flexibility required in some applications, minimize tissue reaction, and protect parylene from degradation in vivo an additional outmost layer of polydimethylsiloxane (PDMS) is desired. In such a scenario, the adhesion of PDMS to parylene is of critical importance to prevent early failure caused by delamination in the harsh environment of the human body. Towards this goal, we propose a method based on creating chemical covalent bonds using intermediate ceramic layers as adhesion promoters between PDMS and parylene.To evaluate our concept, we prepared three different sets of samples with PDMS on parylene without and with oxygen plasma treatment (the most commonly employed method to increase adhesion), and samples with our proposed ceramic intermediate layers of silicon carbide (SiC) and silicon dioxide (SiO2). The samples were soaked in phosphate-buffered saline (PBS) solution at room temperature and were inspected under an optical microscope. To investigate the adhesion property, cross-cut tape tests and peel tests were performed. The results showed a significant improvement of the adhesion and in-soak long-term performance of our proposed encapsulation stack compared with PDMS on parylene and PDMS on plasma-treated parylene. We aim to use the proposed solution to package bare silicon chips on active implants.

A robust superhydrophobic and highly oleophobic coating based on F-SiO2-copolymer composites

Superhydrophobic and highly oleophobic coatings have the potential for self-cleaning, anti-icing, optoelectronic and antifouling application. In this study, emulsion polymerization and sol-gel methods were employed to prepare a new superhydrophobic and highly oleophobic coating. The structures, surface morphology and the properties of the coating were analyzed by IR, SEM, TG and CA. Pencil scratch test and cross-cut tape test were performed to evaluate the coating mechanical properties. The coating exhibited superhydrophobicity with a water contact angle of greater than 150° and a sliding angle of 4.42° as well as high oleophobicity as demonstrated by a diiodomethane contact angle of 147.41° and a sliding angle of 9.85°. The coating exhibited 6H pencil hardness and 5B cross-cut adhesion properties. These interesting and robust properties make them promising candidates for some applications.

Improved adhesion of polyurethane-based coatings to tin surface

Polyurethane (PU)—based conformal coatings which protect electronic components and boards from harsh environmental exposures were further developed to mitigate the tin (Sn) whisker growth in lead (Pb)—free electronics. As a means of achieving this goal, the adhesion mechanics of PU-based conformal coating on tin surfaces was investigated. We attempted to improve the interfacial adhesion between PU-based conformal coatings and tin (Sn) as it slows down the formation of tin whisker growth. A multi-layer sandwiched specimen made between two Si beams was employed to create an interface between PU coating and Sn for four-point bending testing (4PBT). The result shows that PU has strong adhesion to Sn while polyurethane acrylate (PUA) has much weaker adhesion to Sn. The PUA adhesion, however, increased by introducing a silane agent ((3-Aminopropyl)triethoxysilane) on the tin surface, which is covalently bonded to PUA. The adhesion improvement of a modified tin surface was also confirmed by a simple cross-cut tape peeling test. Post fracture analysis suggested that blocking the reaction between bare Sn surface and the acrylate component contribute to improved adhesion.