Journal of Coatings Technology and Research最新文献

Traditional polyurethane (PU) catalysts, especially dibutyl tin dilaurate, face scrutiny over toxicity concerns, leading to interest in safer alternatives. In an unexpected turn of events, research into a commercially available antibacterial agent revealed that it drastically reduced the pot life of PU coatings. Experiments show that when PU coatings were formulated with the antibacterial agent as catalyst, drying time and solvent resistance were improved as compared to traditional tin and zirconium catalysts. Further analysis showed that this was the result of copper compounds and it could be shown that a similar catalytic effect was achieved through Cu(II)-sulfate and Cu(II)-acetate. Such copper salts are not yet commonly known as replacements for tin catalysts. Possible mechanisms such as heterogenous catalysis or in-situ formation of the active compound were discussed.

In this study, coated fabrics were developed using waterborne polyurethane (WPU) containing pomegranate peel (PoP) powders of varying particle sizes. The objective of this research is to diminish the synthetic polymer content by adopting a sustainable approach through the utilization of food waste and functionalized fabrics by using PoP powders with antibacterial properties. In the initial phase of the study, PoP powders were characterized based on parameters such as particle size, moisture content, water activity, water absorption capacity, total phenolic content, and antioxidant activity. Secondly, cotton fabrics were coated with WPU containing PoP powders (10 wt%). While it was observed that the particle size of PoP powders did not make a significant difference in the color and stress-strain values, antibacterial analysis showed that the coatings containing powders with the lowest particle distribution (18.2–81.7 µ, D₅₀: 42.77 µ) resulted in larger inhibition zones. Consequently, functional fabrics with antibacterial properties against both S. aureus (Gram-positive) and P. aeruginosa (Gram-negative) bacteria were composed by incorporating PoP powders as fillers into WPU-coated cotton fabrics.

This work explores how cenospheres (hollow microsphere) can provide a flame-retardant ability to the waterborne acrylic coating. For this purpose, the intumescent fire-retardant coating was prepared on the steel surface, from the acrylic emulsion polymer, flame-retardant additives (ammonium polyphosphate, melamine, pentaerythritol), and flame-retardant fillers (TiO₂, Al(OH)₃). The experimental results showed that after 60-min fire resistance test under burning torch of 900–1000 °C, the backside temperature of coated steel was in the range of 200–250 °C. Addition of cenosphere into the acrylic polymer coating (at 2–10 wt%) enhanced its fire resistance performance by reducing the backside temperature of coated steels from 27 to 76 °C, as compared to the pure coating without FACs. Data from the furnace test showed that the presence of FACs in coating reduced its intumescent factor (from 14.9 to 33.5%) but produced the denser char layer with a better heat shielding ability. XRD analysis confirmed the interaction between cenosphere and coating matrices at high temperatures by forming the heat-stable compounds. TGA data demonstrated that increasing the content of FACs in coating increased its char weight residue at high temperatures and enhanced its thermal stability and fire resistance. Data from the mechanical test indicated that the presence of cenosphere in the acrylic polymer coating did not affect its hardness but decreased its adhesion to the steel surface (from 5.3 to 23.8%).

Graphical abstract

Fluorocarbon surfactants are widely used, especially in the emulsion polymerization of fluoropolymers, due to their high surface activity, excellent stability, and excellent compatibility. However, the long-term environmental pollution of perfluoroalkyl and polyfluoroalkyl groups in fluorocarbon surfactants has made them banned. Here, we designed and prepared an environmentally friendly zwitterionic fluorocarbon surfactant (PFSC) through shortening fluorocarbon chains and covalent bonding them with the zwitterionic groups, and further demonstrated the effect on the emulsion polymerization of fluoropolymers. The results showed that the surface tension of the emulsion after adding PFSC reached 12 mN/m at a concentration above 0.05%, which is significantly superior to that of perfluorooctanoic acid (PFOA). The study also examined the reaction kinetics, emulsion particle size, and emulsion stability during the emulsion polymerization reaction. The results demonstrated that the fluorinated surfactant exhibits excellent emulsification effects and can serve as an alternative to PFOA. This work presents the synthesis strategy of a new environmentally friendly zwitterionic fluorocarbon surfactant for high-efficiency emulsion polymerization of fluoropolymers.

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.

Plasma electrolytic oxidation (PEO) has evolved as a versatile technique for depositing low surface energy organic-based materials useful in fabricating superhydrophobic (SHP) coating materials. The application of silane-based polymeric organic materials atop PEO coating is the most common method to prepare coating materials for wetting and corrosion protection. Herein, the latest developments in PEO-based coatings employing polymeric/silane-based organic materials with the inclusion of ceramic oxides are reviewed, with emphasis on the structure, wettability, and corrosion resistance. The relevant and existing fundamental design theories and strategies for fabricating highly efficient SHP PEO coatings are also outlined and discussed. The systemic design of SHP coatings by deposition from organic particle dispersion and their inclusion into PEO-micropore layers, as well as the most important parameters affecting the properties of PEO-assisted SHP-based coatings, are highlighted. Furthermore, the merits and challenges of the PEO-assisted SHP-based coating fabrication are critically evaluated to identify remaining challenges and future research directions.