Journal of Coatings Technology and Research最新文献

Condensation of fog droplets on polyethylene (PE) films significantly impairs light transmission of the film. This study introduces a PVA/Al₂O₃ antifogging coating, applied to PE films using polyvinyl alcohol (PVA) and nanoaluminum sol. The resultant coatings exhibit superior wettability and an extended antifogging lifespan. Specifically, the coating maintains a low contact angle of 21.1° and demonstrates an antifogging duration of up to 60 days in a 60°C hot fog environment. Notably, light transmission at 500 nm wavelength is enhanced by 3.5% with the PVA/Al₂O₃ coating compared to the uncoated PE film, thereby facilitating plant photosynthesis. Moreover, the coating displays a remarkable self-healing capacity upon external damage, significantly prolonging the antifogging film’s durability.

Nonionic polyacrylate (NPA) emulsions were synthesized through emulsion polymerization employing methyl methacrylate (MMA), lauryl methacrylate (LMA), butyl acrylate (BA), hydroxypropyl acrylate (HPA), acrylamide (AM), acrylic acid (AA), and N-hydroxyethyl acrylamide (NHEMAA) for raw materials. Later, some additives were mixed into the emulsion to create a printing coating which was used for digital inkjet printing on fabric surfaces. The effects of different MMA/LMA ratios on the properties of NPA emulsions were discussed and analyzed. In addition, the particle morphology, chemical structure, and surface morphology of the printed coatings of NPA emulsions were also characterized. The results showed that the highest absolute value of zeta potential and the most stable and relatively good properties of the emulsions were obtained at a ratio of 3:2 MMA/LMA. As the ratio of MMA/LMA increased, the screen blocking performance decreased, and the color intensity, rubbing fastness, and washing fastness all improved. Furthermore, the addition of NHEMAA improved the application performance of the printing coating. The optimal application performance of the printing coating, made from NPA emulsion, was achieved when using a MMA/LMA ratio of 3:2 and adding 2 wt% NHEMAA.

One-dimensional structured fillers play a crucial role in promoting the rapid and spontaneous healing of defects induced by damage in self-healing coatings. This innovative type of self-healing coating prevents the substrate material from corroding, thereby significantly extending its service life. The modification of self-healing coatings with one-dimensional structured fillers relies on functional additives to efficiently heal coating damage, distinguishing it from traditional approaches involving microcapsules and nanoencapsulated particles. The incorporation of advanced fillers not only enhances the local reconstruction efficiency and mechanical properties of the coating but also enables the coating to heal the damage repeatedly. In this paper, the latest research progress on one-dimensional structured fillers for self-healing coatings is reviewed from three aspects: types of functional fillers with one-dimensional structures, packaging processes for repairing agents in fillers, and self-healing mechanisms of the composite coating. Furthermore, future work has been proposed to address present problems in the research of one-dimensional structured filler-modified self-healing coatings.

Graphical abstract

One-dimensional structured fillers and their applications in self-healing composite coatings.

Polylactic acid (PLA) was coated on biodegradable Mg–Zn–Mn alloys using a sol–gel coating technique for temporary implant applications. The presence of smooth, dense, crack-free PLA coating was evidenced using Fourier transform infrared spectroscopy (FTIR) and a scanning electronic microscope (SEM) equipped with an energy-dispersive X-ray spectroscopy (EDX) module. The strength of the bond between PLA and the Mg–Zn–Mn alloys was investigated as per ASTM D3359 and found to be 4B. The degradation behavior was evaluated using potentiodynamic polarization and electrochemical impedance spectroscopy in a simulated body fluid (SBF) solution. The corrosion rate of the PLA–Mg–Zn–Mn sample was found to be 0.00363 mm/y, which is 73% better than the bare Mg–Zn–Mn sample (0.00493 mm/y). In addition, the results of the cytotoxicity assay indicated the cytocompatibility of the implant material on MG-63 osteoblast-like cells, confirming its safety on the bone cells. The efficacy of the use of PLA coating on the biodegradable Mg–Zn–Mn is due to the synergistic effect of both physical and chemical interactions between the PLA layer and the substrate.

The properties of acrylic-styrene latex (ASL) were investigated  using two different nucleation methods by changing the sequence of addition of components, without changing the overall composition of the systems. In the first method, the semi-batch method was used and in the second method, the seeded semi-batch method was used and these were named ASL-1 and ASL-2, respectively. The latexes were characterized by dynamic light scattering, differential scanning calorimetry, tensiometer, gel permeation chromatography, viscometer, scanning electron microscopy, and transmission electron microscopy. The results showed that despite having the constant compositions, the two latexes have significant differences in different parameters studied. Sample ASL-1 showed higher zeta potential, glass transition temperature, surface tension, number average molecular weight and viscosity compared to sample ASL-2, but showed lower particle size. The two synthesized ASLs were also evaluated for their potential for pigment wetting and dispersion, as measured by the color development, by incorporation of three pigment pastes (red, green and blue). The study showed interesting findings that for each color pigment paste, ASL-1 produced deeper color tone than ASL-2. Also, color differences (L, a, b scale), contrast ratios, and gloss of ASL-1 and ASL-2 latexes-based pigment pastes were compared.

Here, we have evaluated water-based paint formulations containing mineral binders, silver nanoparticles, and titanium dioxide. Scanning electron microscopy analysis of dried film samples showed that the paint base was highly porous, and that paint formulations containing 10% and 20% titanium dioxide had different surface morphology. CIELab measurements for methylene blue coloration decay showed that photocatalysis was more efficient for the samples with 20% titanium dioxide. Under ultraviolet radiation, silver nanoparticles contributed to photocatalysis performance. Contact angles proved that titanium dioxide concentration and type defined the wetting characteristics. The samples with 20% TiO₂ displayed porous surfaces with better adsorbance characteristics, higher wettability, and improved heterogeneous photocatalysis.

Multifunctional anti-corrosive coatings are a key focus in the development of modern coatings. In this study, the corrosion inhibitor benzotriazole (BTA) was loaded onto fumed silica (SiP) through physical adsorption, and then the surface of SiP was modified with octadecyl trimethylsilane (OTMS) to create a modified fumed silica supported by BTA (BTA-SiP@OTMS). The resulting sample was blended with epoxy resin to create a composite coating with both anti-corrosive and hydrophobic properties. The OTMS modification effectively covers the surface of the fumed silica, transforming the composite coating from hydrophilic to hydrophobic. This hydrophobicity prevents the penetration of corrosive mediums. The addition of BTA-SiP@OTMS significantly increases the impedance value of the composite coating, indicating improved corrosion resistance. Due to its hydrophobic and anti-corrosion properties, the composite coating shows promising potential in weather-resistant coatings.

The corrosion protection of aluminum alloys is severely compromised by marine environments, demanding the formulation of efficient protective coatings. Epoxy resin, diglycidyl ether of bisphenol A (DGEBA), and curing agent diethylenetriamine (DETA) were used with the mixing ratio of 100:12 to synthesize functionalized SiO₂/GO-based composite coatings and investigate the corrosion protection efficacy for aluminum alloy AA6061 in marine environments. To boost the coatings' barrier and anticorrosive attributes, functionalized silica (FSiO₂, with 0, 3, 6, 9, 12, and 15 wt%) and graphene oxide (GO) were jointly incorporated into the DGEBA/DETA epoxy-hardener system for producing composite coatings. The functionalization of silica particles using 3-aminopropyl-triethoxysilane and synthesis of GO was successfully carried out, according to the Fourier transform infrared spectroscopy evidence. The structural properties were investigated by X-ray diffraction. The hydrophobicity tests were conducted for the measurement of the contact angles. The highest static contact angle (126° ± 2) and the lowest contact angle (74° ± 1.5) were recorded for the sample EHS₉GO₂ and AA6061, respectively, which showed that EHS₉GO₂ coating had the most hydrophobic behavior. An adhesion test (method B, tape test) was performed on prepared coatings to check the quality of adhesion with the substrate aluminum alloy AA6061. The neat epoxy coating (EHS₀GO₀) displayed a fair adhesion rating of 3B, while EHS₉GO₂ coating exhibited excellent adhesion (5B) with substrate AA6061. Furthermore, electrochemical impedance spectroscopy and potentiodynamic polarization tests were employed for assessing the electrochemical behavior and anticorrosion performance of the prepared coatings. It was observed from the Bode plot, that the impedance magnitude/modulus for EHS₉GO₂ at lower frequencies was the highest as compared to other samples during immersion in the artificial seawater. The bare aluminum alloy substrate AA6061 had the highest corrosion rate of value 0.10483 ± 0.00198 mm/year, due to the direct contact with the electrolyte. Moreover, the highest value of E_corr (356 ± 0.42 mV) and lowest values of I_corr (0.18 ± 0.03µA), β_a (48.7 ± 2 mV/decade), and β_c (28.8 ± 1 mV/decade) were witnessed for EHS₉GO₂ coating, showing significant anticorrosion efficiency against the corrosive electrolyte.

Cultivation-based and DNA-based methods for determining the bacterial load and the composition of the bacterial spectrum have been successfully established for media in electrodip painting, and used for the detailed analysis of the contamination situation in an E-coating system of an automobile plant in Germany. Dominating representatives of the genus Microbacterium spp., the orders Burkholderiales and Pseudomonadales, the family Cytophagaceae and the genera Corynebacterium spp., Sphingomonas spp., and Stenotrophomonas spp. were used for inactivation experiments. Different pulsed electric field (PEF) parameters were studied for an effective and target-directed inactivation of defined bacterial suspensions containing mixtures of Gram-positive as well as Gram-negative bacteria, but also single species suspensions in adequate liquids. PEF treatment with pulse durations longer than 1.0 µs effectively killed bacteria even in low conductivity media, regardless of whether the pulses were unipolar or bipolar, indicating that the choice of pulse shape does not limit the design of the PEF system. Model calculations showed that for efficient treatment in bypass mode, a high treatment flow rate is required rather than a high inactivation efficiency of the PEF treatment. By using specific treatment parameters, such as bipolar pulses of 50 k Vcm⁻¹ and a treatment energy of 40 J mL⁻¹, a significant reduction in both Gram-negative and Gram-positive bacteria (> 2 log₁₀ reduction) can be achieved while minimizing electrode corrosion and coating degradation. PEF treatment proves to be an effective alternative to the use of biocides in an E-coating system and can help maintain a bacteriostatic environment in the system by operating at different points, in transfer flow or bypass mode, ensuring biocide-free operation.

The main factors that lead to fruit spoilage are ethylene and microbial contamination. The majority of existing studies focus on single regulation tools for extending fruit shelf life, such as controlling ethylene concentration or inhibiting microbial contamination. The objective of this study was to fabricate zein–natamycin (Z-Nt) films that utilize the synergistic effect of zein and natamycin to extend the shelf life of fruits in terms of ethylene adsorption and microbial inhibition. The mechanical properties, contact angle, water vapor permeability (WVP), oxygen permeability (OP), ethylene adsorption efficiency, antimicrobial properties, and fruit preservation tests were used to characterize the performances of the Z-Nt films. As the natamycin content increased, the films presented an increase in contact angle and a decrease in WVP, indicating an increase in the hydrophobicity of the films. Furthermore, the natamycin content of the films is inversely proportional to OP and positively proportional to ethylene adsorption efficiency. The antimicrobial properties of the films were evaluated against Geotrichum candidum strain and Wickerhamomyces anomalus isolate. Inhibition of mold growth was observed for all natamycin-containing films. Thus, in the case of bananas, the film has a significant mitigating effect on the browning rate, weight loss rate, and hardness of bananas within a certain storage period. It can therefore be concluded that the film, as a bio-based material, has good application value for extending the shelf life of fruits and improving their storage quality.