Journal of Coatings Technology and Research最新文献

Superwetting materials play a crucial part in the fields of chemistry and materials science and draw increasing attention. Among the various applications, superwetting materials demonstrated up-and-coming potential in oil spill remediation. Herein, we report on the preparation of silver-coated copper mesh via a facile chemical deposition and annealing treatment approach that requires neither complex devices nor modification with toxic organic molecules. The resulting sample exhibited remarkable water repulsion (water contact angle of ~ 158° and sliding angle of ~ 1°) and oil affinity (oil contact angle of ~ 0°), contributing to superior separation ability toward various oil–water mixtures (hexane, toluene, benzene, chloroform, tetrachloromethane, kerosene, gasoline, diesel) or effectively cleaning up the floating or underwater oil spill. Moreover, the resulting silver-coated superhydrophobic/superoleophilic copper (Ag-coated SS Cu) mesh demonstrated great durability upon the water flow impact or the abrasion test and was able to continuously separate the toluene–water mixtures over 20 times with an efficiency over 97%. In addition, the sample readily prevented surface fouling via self-cleaning process and exhibited antibacterial ability toward Escherichia coli, Staphylococcus aureus, and Bacillus subtilis as witnessed by the corresponding bacteriostatic circle (11.38 ± 0.76 mm, 12.65 ± 0.68 mm, and 12.87 ± 0.72 mm, respectively) in the Petri dish.

Dust deposition on photovoltaic systems has a significant impact on the transmittance, temperature, and roughness, causing reductions in their power generation efficiency and lifetime. A promising approach to deal with this problem relies on the use of superhydrophobic coatings to impart the surfaces of these devices with self-cleaning properties. In this work, materials with different chemistry and morphology were added to an acrylic dispersion to create hydrophobic surfaces using a non-fluorinated coating simple strategy for glass substrates. Results showed that materials with more complex morphology, namely the spherical shape of silica nanoparticles, and the needle-like and prism-like structures of zinc oxide, imparted the glass with higher water contact angles. All coatings prepared displayed self-cleaning features and good adhesion to the glass substrate. Coatings comprising silica nanoparticles, zirconia and alumina modified with HDMTS were the best ones to prevent ice formation. In terms of chemical stability, all the coatings resisted acidic conditions close to acid rain pH and solvents with mild polarity. Therefore, the coatings proposed hold great potential to expel dust contaminants and prevent ice formation of photovoltaic devices, increasing their lifetime and power generation efficiency.

Achieving stable dispersion of titanium dioxide (TiO₂) particles is crucial for their practical applications in various fields. However, stabilizing pigment TiO₂ (200–300 nm) in aqueous systems with low viscosity (~ 10 cP) presents a significant challenge. In this work, we proposed a simple strategy using dispersant Disuper S9100 as dispersant and polyethylene glycol (PEG) as wetting agent to achieve single-dispersed TiO₂ particles with long storage stability and good re-dispersibility in low viscosity systems. The effect of PEG average molecular weight on the stability and re-dispersion performance of TiO₂ dispersion was investigated. Our study showed that PEG molecules were adsorbed on the surface of TiO₂ particles through hydrogen bonding, and synergized with nonionic polymeric dispersant Disuper S9100 to increase the steric hindrance between the particles. Due to the different adsorption conformations of PEG molecules, the dispersion stability and re-dispersibility of TiO₂ particles was gradually improved with increasing PEG average molecular weight. However, PEG molecules with excessively high molecular weight weakened the dispersion stability of TiO₂ particles. Overall, our findings suggest that the proposed strategy offers a promising approach to achieving stable TiO₂ particles in low viscosity systems.

Gluing polyolefins [e.g., polyethylene (PE) and polypropylene (PP)] results in a very challenging task. The main reason relies on their low surface energy, which reduces the affinity between the polyolefin surface and the chosen adhesive. To tackle this problem, the most commonly used solutions are physical surface treatments, such as plasma, corona, and flame, which introduce hydrophilic moieties on the plastics surface, thus increasing their surface energy. These approaches require special setups, are unspecific, and can induce material degradation. Furthermore, they provide a transient solution, making the storage of pretreated substrates not recommended. In this work, we developed an easy-to-apply primer for durable bonding of adhesives on PE and PP, as robust alternative to physical treatments. Our primer contains a surface-anchoring moiety and an adhesive-binding group to covalently react with the polyolefin substrate and with the glue. As a surface-anchoring moiety, we chose the perfluorophenylazide (PFPA), which is known to undergo a C–H insertion reaction upon UV activation, while as adhesive-binding groups, we selected OH functions, which can covalently react with the most common commercially available glues. When these two features (i.e., PFPA and OH) are combined in a single molecule, the reaction with the substrate does not occur and the molecule is only physisorbed, inducing no adhesion improvement. Chemisorption only occurs with bicomponent formulations, comprising a hydrophobic trifunctional PFPA and a polymer bearing OH and PFPA groups. Those induced improved adhesion on PP compared to the golden standard plasma with polyurethane-based and two-component epoxy adhesives. Storing the coated substrates at room temperature for up to two months did not alter the adhesion performance, thus further ascribing the developed primers as a promising alternative to plasma treatment.

To improve the corrosion resistance and antibacterial adhesion properties of AZ31 magnesium alloy as an orthopedic implant material, superhydrophobic hydroxyapatite/lauric acid composite coatings (HA/LA) were successfully fabricated on AZ31 magnesium alloy utilizing the hydrothermal method and followed by immersion treatment in lauric acid solution. The underlying HA coating synthesized by hydrothermal technique presents a micro-/nanohierarchical structure, appearing superhydrophilic, while the composite coatings (HA/LA) obtained by subsequent treatment with lauric acid exhibited excellent superhydrophobic properties with a contact angle of 152.5 ± 1.2° and a rolling angle of 1.5 ± 0.3°. Electrochemical measurements and long-term corrosion resistance test conducted in simulated body fluid (SBF) indicate a significant enhancement in the corrosion resistance of the HA/LA composite coating. Meanwhile, in vitro bacterial experiments demonstrated that the superhydrophobic composite coating surface was able to reduce the adhesion of adherent Escherichia coli and Staphylococcus aureus by more than 98%, showing excellent antibacterial adhesion properties, indicating that the superhydrophobic HA/LA composite coating in this work grants magnesium alloy with excellent corrosion resistance and antibacterial properties.

Excessive heat build-up of painted surfaces due to solar radiation and the resulting increase in interior temperatures is undesirable and even dangerous for roofing, facades, and other structural elements. One way to reduce surface temperature is to apply suitably pigmented organic coatings exhibiting high solar reflectance properties. The use of high solar reflectance pigments in paints resulted in coatings with high total solar reflectance (TSR) values, and thus with the ability to reduce the temperature of the painted substrate. The coatings were tested under laboratory and outdoor conditions on two livestock farms. It was found that the developed coatings exhibit significantly higher TSR values than commercial coatings of the same colors designed for painting roofs. The TSR values do not change when the coatings are exposed to the weather.

Biofouling release coatings (BRCs) have received attention for their potential to limit the negative impacts of biofouling on marine shipping. The calibrated water jet (CWJ, patent # US 8,984,958 B1) can be used to study the effectiveness of BRCs as a function of ship speed. Using a balance of force and linear momentum, we examined the theory and application of the CWJ for simulating the effect of ship speed on biofilm release for surfaces fouled under (1) laboratory and (2) natural conditions. Greater fouling release corresponded with an increase in CWJ pressure and, therefore, simulated ship speed for the surfaces coated with HullKote. The effectiveness of the CWJ was further confirmed for biofilm release from glass fouled naturally by submersion in flow-through seawater. A scaling analysis confirms that the results of these small-scale experiments are applicable to larger-scale biofouling release from ship hulls. This study is the first to utilize the pressure of a CWJ to quantify biofouling release as a function of simulated ship speed.

Thermal insulating coatings have important potential for energy saving in the field of building thermal management, but they are difficult to apply on a large scale due to the problem of being waterproof and moistureproof. Herein, we design a two-step spray process to fabricate a thermal insulating superhydrophobic composite coating using epoxy resin mixed with hollow glass microsphere as primer coating and fluorine-modified SiO₂ nanocoating as a waterproof layer. The composite coating shows durable superhydrophobicity and low thermal conductivity [0.051 W/(m·k)], which is endowed with excellent thermal insulating properties under light and heat, contact heat conduction (− 20 to 70 °C), and boiling water scouring environment. These multiple key properties that have been integrated into our composite film are expected to provide unique advantages for applications in building thermal management.

In order to increase the concentrations of bio-based alkyd polyols (or fatty acids) in self-crosslinking polyurethane dispersions, herein, a series of novel alkyd polyol-based autoxidizable waterborne polyurethane dispersions (AWPUDs) with different fatty acid contents, long storage stability, and low viscosity were successfully prepared by adding dimethylol propionic acid (DMPA) self-emulsifier in the late stage of their synthesis. They and their corresponding curing films were characterized by Fourier transform infrared spectroscopy (FTIR), particle size analysis, rheology measurement, storage stability evaluation, thermogravimetric analysis, dynamic thermomechanical analysis (DMA), etc. The results showed that the addition process of DMPA played a critical role for the excellent features of AWPUDs. Additionally, the crosslinking density, gel contents, and water contact angles of AWPUD films increased with the enlarged fatty acid contents, whereas their water uptake capability decreased. Moreover, a series of AWPUD coatings were prepared, and their properties like drying times, hardness development, pencil hardness, adhesion capability, impact resistance, flexibility, and water resistances were all effectively improved with the increased fatty acid contents, significantly superior to those of waterborne alkyd coatings and waterborne polyurethane coatings without fatty acids.