Journal of Coatings Technology and Research最新文献

Coatings containing functional pigments capable of reflecting radiation in the near-infrared (NIR) spectrum have been coveted in recent years to meet various industrial specifications. In this study, NIR reflective inorganic pigments with the chemical structure of TiO₂, CoAl₂O₄, and (Cr,Fe)₂O₃ were dispersed individually in the continuous phase of organic solvents and thermosetting acrylic polyol to form ready-to-use colorants for NIR reflective coatings. A total of ten different pigments, three TiO₂, three CoAl₂O₄, and four (Cr,Fe)₂O₃, were included. Resin-dispersant compatibility and solvent-pigment compatibility in potential paint formulations were tested prior to dispersion design. The ability of the developed pigment dispersions to maintain the primary particle size distributions was confirmed by stability tests, and UV–Vis–NIR spectra of fresh pigment dispersions drawn-down on steel plates were comparatively evaluated. Although the change in pigment particle size distribution after subjecting the dispersions to different temperatures was negligible, the favorable NIR reflectance obtained by certain pigment dispersions served to select the optimum pigment dispersions within dispersions of the same pigment chemistry. The ALTIRIS 800, 22-5600, and 30C941 dispersions exhibited higher reflectance in the NIR spectrum compared to other developed TiO₂, CoAl₂O₄, and (Cr,Fe)₂O₃ dispersions, respectively, and supported their use in paint designs suitable to autonomous vehicles.

Numerous synergistic anticorrosion methods have attracted great research interest. A silicone-modified self-healing polyurethane composite coating, known as MXene@ fluorinated polyaniline, was synthesized through in situ polymerization of fluorinated polyaniline on the MXene surface using polydopamine to enhance the compatibility between the filler and the polyurethane coating. The anticorrosion efficiency of the coating was examined in a 3.5 wt% NaCl solution via electrochemical impedance spectroscopy. The synergistic effect of polyaniline passivation and the physical barrier effect of MXene indicated that even after 100 d of immersion, the impedance modulus of the composite coating at 0.01 Hz remained above 10⁸ Ω·cm². Additionally, the introduction of disulfide linkages into the coating endowed it with self-healing properties. Owing to the superior photothermal capabilities of MXene, polyaniline, and polydopamine, the polyurethane coating exhibited self-healing abilities in the presence of sunlight. The coating retained its mechanical and anticorrosion properties both before and after the self-healing process. This approach integrates the synergistic effects of MXene, polyaniline, and dynamic disulfide bonds to meet the requirements of coatings in harsh environments, thereby prolonging the lifespan of metals.

There are many harmful chemicals in the wood protection and coating industry. These substances adversely affect human health over time and cause many diseases such as respiratory tract, skin, or lung cancer over time. In this study, bio-based nano-coatings as a replacement of bisphenol-A (BPA) were prepared by both protecting the wood organically and trying to prevent applications that would adversely affect human health. This study was aimed to improve wood properties such as oven and air-dry densities and water absorption (WA) from physical properties, color, gloss, and roughness from surface properties after natural weathering, and compression strength parallel to the grain (CSPG) from mechanical properties by coating these materials on Oriental beech wood. New bio-based epoxide–amine (EP) coatings were preferred over BPA material and their nano-composite coating derivatives including fullerenes, graphene, and carbon nanotubes were prepared by reactions of epoxy-functionalized tung. A diamine hardener (isophorone diamine) and epoxide tung oil (ETO) doped with nanoparticles were cured, and their physical properties were also determined. Consistent with our previous work, glycidyl methacrylate and tung oil were preferred to form epoxy-functionalized tung oil (ETO) by opting for a Diels–Alder reaction. The new bio-based epoxide–amine-cured systems were created at ambient temperature using a 1:1 epoxy-to-amine molar ratio. The specimens covered with epoxide nano-composites exhibited greater water resistance than the control group. When the surface properties of the epoxy nano-composite-coated specimens after weathering were examined, a more stable color change was observed compared to the control group. Furthermore, while the glossiness of the epoxide nano-composite-coated specimens decreased more than the control group, their roughness increased more. CSPG of epoxy-coated specimens increased a little bit compared to the control group, but no statistical difference was found.

Superamphiphobic coating with excellent optical transmittance has immense potential for utilization in many fields. However, it is challenging to maintain superamphiphobic surface with high transparency. Herein, a lotus leaf-inspired double-layered coating is proposed. The bottom layer of the coating consisted of fluorosilane-modified epoxy resin, while the top layer was composed of fluorosilane-modified SiO₂ and cellulose nanofibers (CNFs). The trends of optical transmittance and oil-water contact angle of the coating at different mass ratios between SiO₂ and CNFs were systematically investigated, and the stability of the coating was further studied by means of immersion in water, tape peeling, falling sand abrasion, and ultraviolet radiation. Experimental results showed that the coating exhibited the best comprehensive performance when the mass ratio of SiO₂ to CNFs was 1:1. The coating exhibited optical transmittance of 79%, while the contact angles of water, glycerol, glycol, and hexadecane were up to 169°, 163.5°, 155.2°, and 125.4°, respectively. Even after the stability test, the coating still showed a good superamphiphobic performance. This demonstrates that the coating exhibited excellent optical transmittance, good chemical stabilities, and high mechanical stability.

Graphical abstract

Mechanical strength is an important factor that affects and limits the life of surface antireflective (ARC) coatings such as optical lenses, photovoltaic panels, and liquid crystal displays. In this work, a network-structured silica sol was prepared using tetraethyl orthosilicate (TEOS) and methyltriethoxysilane as silicon sources. Triethoxy(1H,1H,2H,2H-nonafluorohexyl)silane (C₄FTES) was used to modify the acid-catalyzed silica sol. Finally, the mixed sol was plated on the surface of polymethyl methacrylate by impregnation-pulling method. The coating obtained after drying at 100°C showed a maximum transmittance of 97.98% in the visible wavelength range (400–800 nm). The coating still maintained good optical properties after undergoing various wear-resistant tests such as sandpaper abrasion and cotton ball friction. Moreover, the pencil hardness test of the coating improved from 5B to 3H after it was modified by short-chain perfluoroalkyl groups (C₄FTES). This work required only low-temperature treatment without calcination to prepare a silicon-based ARC coating formed by copolymerization of C₄FTES and TEOS, and the mechanical properties of the coating meet actual needs. This easy-to-operate preparation method greatly expands the application scope of silicon-based ARC coatings in the field of heat-sensitive materials.

Graphical abstract

The polymethyl methacrylate (PMMA) substrate is coated with a fluorine-containing coating with a network structure, which greatly improves the transmittance and surface hardness of the substrate.

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.