Journal of Coatings Technology and Research最新文献

Over the last decade, superhydrophobic surfaces with their new functional and structural properties have attracted a lot of interest both in the scientific research environment and in the industrial environment because of their potential to be applied in several fields, including anticorrosion, water/oil separation, ice repellency, and above all self-cleaning. This review, which should be of interest to students, researchers, and also industries focused on the chemistry of coatings, has been made with the aim of citing, explaining, and comparing in detail the structural and functional properties, the formulation techniques, the advantages, and the inconveniences of the majority of materials most used until now, and on the other hand to meet all our needs to facilitate the choice of materials for the preparation of superhydrophobic coatings according to the desired properties. This review provides a detailed analysis of recent advances in the preparation of superhydrophobic surfaces using polymeric coatings. In a significant way, the theoretical principles for the manufacturing of this type of surface have been explained, and the factors impacting the surface superhydrophobicity have been proposed. Also, an in-depth examination of the preparation approaches is categorized according to types of polymers such as polydimethylsiloxane (PDMS), polymethyl methacrylate (PMMA), polystyrene (PS), polyvinylidene fluoride (PVDF), polyurethane (PU), epoxy, and other polymers. Finally, the applications and challenges related to the applicability of this type of coating in everyday life are highlighted.

The application of mesoporous silica nanoparticles (MSN) as smart containers to distribute corrosion inhibitors gradually over time for metal protection has been well documented. This material possesses unique properties such as tunable surface and pore, high thermal and chemical stability, large pore volume and pore size, relatively low toxicity, and water solubility. These properties of MSN enable it to encapsulate large volumes of corrosion inhibitors which upon installation of an appropriate gatekeeper can release inhibitors at a controlled rate thereby improving the service life of coatings when dispersed within. In this mini-review, we look at the structure and properties of MSN, various synthetic routes reported in the literature, the nucleation and growth mechanism proposed thus far, some of the challenges still encountered in the synthesis of MSN as well as various ways it has been applied as a “smart” container for the controlled release of corrosion inhibitors in coatings.

Sol–gel based coatings are used to protect metals from corrosion. They offer a barrier to the electrolyte penetration, but they do not provide active corrosion protection. Therefore, corrosion inhibitors are often added to sol–gel formulations to improve the overall corrosion behavior. Sol–gel-based coatings typically require relatively high temperatures to be properly cured, which supposes high energy consumptions and might damage some of the precursors of the formulation, including corrosion inhibitors incorporated to improve the coating’s properties. In this study, the effect of diethylenetriamine (DETA) as a curing agent, and yttrium 4-hydroxy cinnamate [Y-(4OHCin)₃] as corrosion inhibitor, on the chemistry and corrosion performance of a hybrid silica-epoxy formulation are investigated. Solid nuclear magnetic resonance and attenuated total reflectance Fourier transform infrared spectroscopy are carried out to analyze the influence of the curing agent and the corrosion inhibitor on the chemical structure of the coating. The corrosion performance is assessed by means of electrochemical impedance spectroscopy, and the results are evaluated considering the chemical study and the interaction between the different compounds.

This study aims to create paper packaging by developing paper coated with silver-exchanged zeolite that provides the necessary antibacterial properties. Various coating solutions containing different concentrations of silver-exchanged zeolite (0.1%, 0.2%, 0.3%, and 0.4%) by weight of starch mixed with starch were prepared. The study investigated the effects and properties of these silver-coated papers. Examination of the microscopic structure of the surface coated paper revealed that the coating solution effectively filled the pores of the paper, resulting in a smoother surface with even distribution of silver-exchanged zeolite. The basis weight and thickness of the coated paper increased after the coating process. The paper coated with silver-exchanged zeolite demonstrated the ability to inhibit the growth of both Gram-negative bacteria (Staphylococcus aureus) and Gram-positive bacteria (Escherichia coli). Notably, the paper coated with 0.1% silver-exchanged zeolite exhibited improved mechanical properties and a higher water contact angle compared to uncoated paper (61°–88°). This suggests that paper coated with silver-exchanged zeolite has the potential to be used as antibacterial paper for packaging food products.

In this study, we utilized nanocomposites prepared from nanosilica (SiO₂) and various polythiophene derivatives as enhancement additives for acrylic coatings. The nanocomposites were synthesized in a nitrogen environment using FeCl₃ as a catalyst in a chloroform solvent. The weight ratio of nanosilica to monomers was 2/1, specifically for the compounds (5-benzo[d]thiazol-2-yl)-7-methoxy-2-(thiophen-3-yl)benzo[d]oxazole (P1), 3-(2-benzothiazolyl)thiophene (P2), and 5-(benzo[d]thiazol-2-yl)-2-(thiophene-3-yl)benzo[d]oxazole (P3). Analysis techniques including IR, TGA, SEM, and UV–Vis were employed to demonstrate the formation of polythiophenes on the surface of the nanosilica. The presence of polythiophenes on the nanosilica broadened the UV absorption region. Upon adding the nanocomposites to acrylic coatings, the UV absorption intensity of the coatings was increased. Notably, the coating containing SiO₂-P3 nanocomposite exhibited the highest abrasion resistance among all the investigated samples. By varying the content of SiO₂-P3 nanocomposite, we observed enhanced abrasion resistance, adhesion, pencil hardness, and gloss of the acrylic coating. The maximum values were achieved when the content of SiO₂-P3 nanoparticles was 2 wt.%. The SiO₂-P3 nanoparticles were uniformly dispersed in the acrylic coatings, leading to an improvement in the coating's sunlight-reflective ability. Consequently, the acrylic/SiO₂-P3 nanocomposite coatings exhibited potential for outdoor applications, particularly as UV-resistant coatings.

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%).

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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.