When a corrosion inhibitor (CI) is directly incorporated into the paint matrix, it improves the initial corrosion protection. However, this approach often results in leaching of CI from paint coatings, thereby reducing its long-term protection under prolonged exposure to a corrosive medium. Encapsulation or intercalation of the CI inside a nanocontainer and its subsequent incorporation into the alkyd-based paint enable extended corrosion protection by preventing leaching and allowing controlled release of CI In the present work, a cerium-based salt was used as the corrosion inhibitor and intercalated through cation exchange within a layered montmorillonite pillared clay (PC) nanocontainer. An optimized amount of cerium-intercalated PC was incorporated into the paint, deposited on mild steel samples, and cured appropriately. The intercalation of cerium into the PC structure was confirmed by transmission electron microscopy (TEM), X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) analysis. The thickness, surface roughness, and tape adhesion strength were measured to assess the surface characteristics and adhesion behavior of the coated substrates. Electrochemical impedance spectroscopy analysis was carried out on the coated and uncoated samples after immersion in 3.5 weight percent NaCl solution for 1, 25, 50, and 168 h. The charge transfer resistance of coatings generated using Ce3+ modified PC after longer immersion time, i.e., 168 h, was found to be 1.9 × 109 Ω cm2, which is relatively higher than that of coatings generated using only paint and the direct addition of cerium salt into the paint, i.e., 4.5 × 105 and 8.2 × 106 Ω cm2 respectively. Salt spray analysis further demonstrated that the paint coating containing encapsulated corrosion inhibitor exhibited superior protection performance compared to the paint coating and the paint coating with directly incorporated CI Overall, the results demonstrate that the incorporation of PC-encapsulated corrosion inhibitor significantly enhances the long-term corrosion protection performance of the paint coating.
Understanding the scratch behavior of thermoset coatings, such as acrylic–melamine systems, is critical especially in automotive applications where scratch-induced damage compromises the appearance and durability of multilayer coatings. In this study, a three-dimensional finite element model incorporating a strain rate-dependent brittle cracking criterion was aimed to be validated against experimental data to investigate the scratch response of an acrylic–melamine clearcoat under constant load conditions. Three clearcoat formulations with varying levels of blocked isocyanate were characterized. Experimental results demonstrated that increasing blocked isocyanate content increased toughness and friction, thereby delaying crack initiation. Numerical analysis showed that a lower modulus of the clearcoat with the highest toughness reduced tensile stress concentration behind the indenter, while its higher failure strain and critical energy release rate allowed the material to sustain higher applied loads before being cracked. Parametric studies further highlighted the roles of friction coefficient and indenter tip size in governing damage onset. This integrated framework not only clarifies the mechanisms of scratch-induced cracking in automotive clearcoats but also provides a predictive tool for guiding the design of next-generation, scratch-resistant multilayer coatings.
Corrosion remains a considerable problem of concern in the chemical, petrochemical, marine, and energy industries as it is detrimental to the integrity, safety in operation, and costs of maintenance of the equipment. Advanced polymer coatings have emerged as promising candidates based on their tunable chemical properties, high barrier resistance, and compatibility with different functional additives. This review critically examines progress made in polymer-based corrosion protection technologies since 2015 through 2025. It emphasizes their fundamental mechanisms, essential performance properties, and recent advancements. Notably, literature shows significant quantitative improvements such as one to three orders of magnitude enhancement of impedance modulus, inhibition efficiencies over 90
In recent years, the development of advanced corrosion-resistant coatings has become a major research focus because of their broad industrial relevance. This study presents a systematic Taguchi-based optimization, used for the first time to elucidate the individual and synergistic roles of polyaniline (PANI), reduced graphene oxide (rGO), and imidazole (IM) on the anticorrosive performance of epoxy coatings applied on Q235 steel substrates. PANI and rGO were synthesized and characterized by FTIR, XRD, and TGA. A Taguchi experimental design was used to optimize additive concentrations systematically, and coating performance was assessed in 3.5 wt
This study investigates the potential of a hybrid sol-gel based on tetraethyl orthosilicate (TEOS) and (3-glycidoxypropyl)trimethoxysilane (GPTMS) as a pretreatment to enhance the adhesion of epoxy coatings on hot-dip galvanized (HDG) steel. In addition, the effect of incorporating cerium-modified silica (Ce–SiO2) into the epoxy layer was evaluated using electrochemical impedance spectroscopy (EIS) as a function of immersion time in 0.5 M NaCl solution and in salt spray tests. The results confirm the good compatibility of the bilayer system and a significant improvement in the adhesion of the organic coating, especially under wet conditions. These findings highlight the potential of the sol-gel layer as an effective pretreatment before paint application. Furthermore, the incorporation of Ce–SiO2 significantly improved the barrier properties of the epoxy coating, by increasing the crosslinking degree of the polymer matrix, as confirmed by dynamic mechanical analysis (DMA), thereby providing long-term corrosion protection of the bilayer system on HDG steel.
Graphene exhibits exceptional electrical, thermal, and mechanical properties, making it an excellent platform for the development of functional nanocomposites. The incorporation of metal and metal oxide nanoparticles (NPs) onto graphene sheets not only enhances the intrinsic properties of both components but also introduces novel functionalities through synergistic interactions between nanoparticles and graphene surface. In this study, multifunctional cotton fabrics were developed using graphene oxide (GO) and ZnO as well as ZnO/Ag and reduced GO (rGO)/ZnO/Ag nanocomposites. Reduction of AgNO3 on GO/ZnO-coated fabric simultaneously led to the formation of Ag nanoparticles and in situ reduction of GO to rGO. Successful synthesis and non-uniform distribution/surface coverage with some clustering of nanostructures on cotton substrate were confirmed using varied analyses. Photocatalytic performances of ZnO, ZnO/Ag, and rGO/ZnO/Ag-coated fabrics were evaluated through degradation of methylene blue (MB) dye under sunlight. Among all samples, rGO/ZnO/Ag-coated fabric exhibited the highest photocatalytic efficiency, attributed to enhanced charge separation, suppressed recombination of holes and electrons, along with Ag nanoparticles’ electron sink behavior. Additionally, microbicidal capacities of coated fabrics were assessed toward Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) microorganisms. The Ag presence in coated fabrics significantly contributed to both photocatalytic and antibacterial performances due to its excellent electron trapping ability and strong microbicidal capacity. Both cotton fabrics coated with rGO/ZnO/Ag and ZnO/Ag nanocomposites unveiled improved antibacterial efficacies relative to the uncoated cotton and cotton-GO samples, highlighting their potentials for environmental remediation and biomedical antimicrobial textile applications.
Pulsating water jets attract increasing attention for fast screening of rain erosion properties of wind turbine blade coatings. However, compared to natural rain erosion, the difference in experimental conditions adds significant uncertainty to the test results. The present work investigates the effects of impact velocity, exposure time, substrate type, coating elasticity, and impact frequency on the coating erosion process in a high-frequency pulsating water jet. Measurements were compared to data from a whirling arm rig, which, for decades, has served as the industrial standard. For four coating systems, it was shown that to initiate the erosion process, certain water jet threshold velocities are required. Furthermore, under high-frequency impacts, the effects of steel and glass fiber-reinforced epoxy resin substrates, relative to other process parameters, proved insignificant for the erosion process. For elastic coatings, the water jet erosion rate was notably affected by the impact frequency, with high-frequency impacts in the pulsating water jet resulting in a much faster erosion process in elastic coatings than in rigid (stiff) coatings. Variations in experimental conditions, especially the impact frequency, resulted in different coating failure sequences in the pulsating water jet and the whirling arm rig.
Chromate-free corrosion inhibitors are important to establish non-toxic coating formulations for high strength aluminum alloys. A commercially sourced protected benzotriazole (BTA) based corrosion inhibitor was loaded into a 2K epoxy-amine matrix. The coating formulation was then systematically varied—inhibitor loading (IL), epoxy-to-amine ratio (EP:NH2), filler type (FT), and filler amount (FA). In the formulation, BaSO4 and TiO2 were used as filler/pigments. The leaching behavior of BTA from free coating films was evaluated in de-ionized water. It was shown that the commercially sourced protected inhibitor could successfully be incorporated into the 2K epoxy-amine matrix and up to 77
A frequently observed yet poorly explained phenomenon in the study of superhydrophobic surfaces (SHS) is that their measured slip length—a key parameter for drag reduction—appears to increase with the Reynolds number in some experiments. The physical origin of this trend has remained ambiguous, limiting our ability to design and optimize these surfaces. This study was designed to resolve this fundamental ambiguity through a combined approach of experimental analysis and targeted computational fluid dynamics (CFD). We first fabricated a durable, porous superhydrophobic coating on a flexible fibrous substrate. This coating exhibited excellent water repellency, with a high static contact angle of 164.6° and a low sliding angle of 4.3°, confirming a stable, air-trapping Cassie-Baxter state. Drag reduction experiments in a laminar channel flow demonstrated the coating’s effectiveness, showing a significant drag reduction ranging from 5 to 25
Fluorescent corrosion indicators can identify underlying corrosion on metallic substrates by detecting metal ions resulting from corrosion processes. Nevertheless, the direct incorporation of fluorescent probes into the coating may result in numerous adverse effects. To maximize effective application, encapsulating these probes in specific carriers is considered to be a viable technique. In this work, the design and application of a new fluorescent probe were reported, which contains o-benzylaminophenol (BC) as fluorophores and nanomesoporous silica (MSP) as carrier. MSP, characterized by an average particle size of 90 nm, was synthesized using a sol-gel process. BC was synthesized, which exhibited yellowish-green fluorescence upon the addition of aluminum nitrate, methanol, and water. A novel intelligent container with the function of early corrosion warning was developed by incorporating BC into the MSP carrier by vacuum impregnation. BC@MSP smart containers were included in the solvent-based polyurethane coatings and applied on 2024-T3 aluminum alloy. The coating is engineered to identify corrosion within 24 h following exposure to 3.5 wt.
The paper examines the influence of the chain length of the copolymer comprising naturally derived carbon from the bio-monomer on the minimal film-forming temperature of dispersion and the polymeric film’s glass transition temperature, but also the mechanical properties of such a binder in the decorative, low pigment volume concentration paint formulation. The effect of n-dodecyl mercaptan in different weight ratios as a chain transfer agent on the molecular weight of copolymer synthesis in aqueous dispersed media has been investigated. This study confirms its significant role in the termination of physical chains of growing polymers during emulsion polymerization, which has a great impact on the end properties of the dispersion. Partially bio-based polymers with different chain lengths have been examined as a fully petrochemical binder substitute for pigment-binding capacity through wet scrubbing resistance measures for paint coating to assess their suitability and competitiveness compared to acrylic dispersions widely used in this application.
PSF@Oil microcapsules were prepared using a solvent evaporation method, and the effects of key process parameters on their formation were systematically examined through single-factor and orthogonal experimental design. For the average particle size and SEM characterization, the mechanism by which each factor affects the physical properties of the microcapsules was analyzed. The optimal synthesis conditions were identified as 30°C heating temperature, a composite surfactant system of 1 wt
Whether sodium dodecyl sulfate (SDS) can be protonated in water under practically relevant acidities remains unclear because reported pKa values for its conjugate acid, dodecyl hydrogen sulfate (DHS), vary widely. As SDS is widely used as an electrostatic stabilizer in waterborne coating formulations, clarification of its acid stability is of practical importance. SDS protonation was therefore examined by turbidity measurements, acid titration, and 1H NMR spectroscopy. Solutions containing 0.025–0.50 mol L−1 SDS remained fully transparent down to pH ≈ 0, with no turbidity or change upon heating to 45 °C. Titration with 1 M HCl showed a logarithmic pH decrease without buffer or equivalence points, indicating the absence of a measurable aqueous pKa. In 1H NMR spectra (0.10 mol L−1 SDS), only ionic-strength-dependent shifts were observed, while integrals remained constant, confirming full solubility. Protonation, visible as line broadening and signal loss ( 7
Nitrocellulose-based lacquers are used as topcoats in leather finishing applications worldwide. They impart good appearance, durability, and performance. The stability of water-based nitrocellulose (NC) lacquers remains a major challenge for storage stability and leather finishing applications, often limiting their industrial utility. This study compares the stabilizing effectiveness of Carbopol and hydrolyzed polyvinyl alcohol (PVA) in NC lacquer emulsions. Evaluations of emulsion stability, viscosity, pH, zeta potential, FTIR, and film properties, along with leather application tests like gloss, wet/dry rub fastness, have been carried out. It was found that the formulations containing Carbopol exhibited phase separation within one month of storage, indicating limited long-term stability. In contrast, hydrolyzed PVA significantly enhanced emulsion integrity, maintaining stability for more than three months without signs of creaming, sedimentation, or coalescence. The improved performance is attributed to the strong hydrogen-bonding and film-forming characteristics of hydrolyzed PVA, which reinforce interfacial interactions and prevent particle aggregation. These findings demonstrate that hydrolyzed PVA is a superior stabilizer for NC lacquer emulsions and provide a promising approach for overcoming persistent stability issues in water-based NC systems used in the leather finishing industry.
Silicone rubber exhibits inherent hydrophobicity and poor lubrication performance in aqueous environments, limiting its application in medical devices. To address this challenge, we developed a thermosetting lubricating coating by incorporating polyvinylpyrrolidone (PVP) into a polyurethane-based binder system enhanced with silane coupling agent (APTES) to improve adhesion. The coating was applied to silicone rubber substrates pretreated with heptane to ensure uniform and firm attachment. Its performance was evaluated through comprehensive characterization including FTIR, SEM, EDS, contact angle measurements, tribological tests, and antibacterial assays. Results demonstrated that a PVP concentration of 3
This study investigates the mechanisms behind periodic sulfide-induced discoloration of copper-based antifouling coatings exposed at the CoaST Maritime Test Centre (CMTC) in Hundested, Denmark. Both static panels and a rotating cylinder setup were used to assess the impact of hydrodynamic forces on copper release rates and sulfide contamination. Surface analysis techniques, including X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), confirmed that the formation of copper sulfide (CuS) was responsible for the observed blackening of coatings. The results indicate that the rate of copper release did not significantly influence the extent of sulfide contamination. Instead, the rotational movement of the cylinder facilitated the transport of sulfide from deeper water layers to the coating surface, accelerating CuS reaction and precipitation. Computational fluid dynamics (CFD) simulations were employed to modify the rotor setup, successfully disrupting the upward sulfide influx and reducing contamination levels. These findings highlight the role of hydrodynamics and monitoring water parameters in dynamic testing of antifouling coatings and offer practical design modifications to enhance the reliability of antifouling coating exposure tests in environments in risk of sulfide contamination.
This study is significant in the context of energy-efficient buildings. The building sector is a key factor in climate change, consuming large amounts of energy to maintain a comfortable indoor temperature. The energy is mainly derived from non-renewable sources, which do not fulfill the energy demand. Therefore, it is necessary to focus on alternative sources to satisfy the demand. This study aims to improve the coating’s ability to store latent heat by varying the amount of microencapsulated phase change materials (MPCM) in polyester-based organic coating for energy storage buildings. The microcapsule storage capacity can be increased by changing the melamine–formaldehyde (M/F) ratio with a constant core-to-shell ratio. The lauric acid–myristic acid (LA-MA) eutectic phase change material was microencapsulated by using MF as a shell material through an in situ polymerization process. The investigation evaluated the structural, morphological, and thermal properties of microcapsules using Fourier-transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry analysis, and thermogravimetric analysis. In this work, the thermal behavior of MPCM incorporated into polyester-based organic coatings for roofing applications was studied. The coating was prepared with varying percentages of MPCM 1 and tested for various coating properties. DSC result of MPCM 1 has been observed to melt at 39.01 °C with a melting latent enthalpy of 130.45 J/g and crystallize at 34.33 °C with a crystallization latent heat of 131.75 J/g. TGA analysis confirms increases in the thermal stability of MPCM compared to pure PCM. The thermal energy transfer rate was used to measure the time it took for the coated panel to reach a target temperature of 45 °C. Coatings with incorporated microcapsules were analyzed for salt spray to evaluate the potential impact of phase change material (PCM) loading on corrosion resistance.
Persistent flame-retardant fabric design has received a lot of attention owing to fire risks and environmental risks. In this work, a solvothermal synthesis was used to create nano ammonium pentaborate (APB), a chemical based on boron, as a flame-retardant additive. To synthesize a silica nano APB sol using the sol-gel method, tetraethylorthosilicate (TEOS) and nano APB were utilized as a precursor and flame-retardant additive, respectively. The cotton fabric was dip-coated with the sol, and then it was allowed to cure. FESEM results indicate the sol’s successful incorporation. The after-flame time of 20.30 s and after-glow time of 0.00 s are displayed by silica-nano APB@SiO2 treated cotton fabric after conducting the vertical flame test. Thermal study revealed that the combined action of silica and nano APB improved the treated fabric’s stability towards thermal behavior, such as weight loss, breakdown temperatures, and heat flow, which were investigated via TGA and DSC. These studies offer enhanced char production and thermal stability, two crucial components that enhance flame-retardant effectiveness. The limiting oxygen index (LOI) of nano APB@SiO2@cotton fabric rose significantly from 18 for untreated cotton and 18.6 for silica-treated cotton to 26.3 after 12 dip-coating cycles, showing a significant improvement in flame-retardant performance.
Transparent devices often suffer from water fog accumulation that diminishes both transparency and operability, an issue that significantly compromises both safety and practicality. While amphiphilic coatings demonstrate considerable potential for anti-fog applications, precise regulation of the hydrophilic/hydrophobic monomer ratio in the interfacial composition remains crucial. This study employed fluorinated silicone resin as the primary matrix, incorporating amphiphilic oligomers with varying hydrophilic/hydrophobic monomer ratios to develop a series of coatings with tunable wettability. The influence of monomer ratio on the interfacial characteristics and protective performance was systematically investigated. When the ratio of butyl methacrylate to 1-vinyl-2-pyrrolidone reached 4:4 and 2:6, the amphiphilic units reached a state of equilibrium. The silicone-based coatings with balanced amphiphilic units, TOF-B4P4 and TOF-B2P6, exhibited outstanding fog condensation inhibition and accelerated fog dissipation capabilities, reducing fog dissipation time by approximately half. Furthermore, these coatings demonstrated effective resistance to bacterial adhesion (94.2 ± 0.4
In the context of a bio-based circular economy, replacing fossil raw materials with renewable alternatives has become a major trend. Platform chemicals such as itaconic acid and 2.5-furandicarboxylic acid can now be produced from sugars or lignocellulose and used to synthesize fully bio-based polyesters e.g. poly(ethylene 2.5-furandicarboxylate) with thermomechanical and barrier properties comparable to conventional polyesters. Life cycle assessments indicate that these bio-based polymers emit significantly less greenhouse gas than their fossil-derived counterparts, and thermomechanical testing and degradation studies confirm their practical suitability. Current crosslinking methods typically rely on melamine and isocyanates, which pose toxicological and ecological disadvantages. We propose using itaconic acid as a renewable crosslinking component to address these issues, with the crosslinking reaction tailored through catalyst selection. In our work, the incorporation of itaconic units into the polyester was confirmed by SEC (size-exclusion chromatography), 1H-NMR (nuclear magnetic resonance spectroscopy), ATR-FTIR (attenuated total reflectance-Fourier-transform infrared spectroscopy) analysis. Thermal/mechanical properties were characterized by DSC (differential scanning calorimetry) and DMTA (dynamic mechanical analysis). In situ ATR-FTIR and rheology reveal that network formation proceeds via two competing mechanisms: radical C–C crosslinking and oxa-Michael (C–O–C) addition. Catalyst choice dictates the dominant pathway. Brønsted acids (DBSA, MSA) reduce the apparent reaction order to 0.6, whereas a radical initiator (di-tert-butyl peroxide, DTBP) enhances radical crosslinking (apparent order 1.7). In contrast, Lewis acids and metal salts (e.g. AlCl3, Zn(OAc)2) suppress covalent gelation, favouring coordinative and supramolecular interactions over permanent covalent crosslinks. In coating tests, selected itaconate-containing formulations achieved an optimal balance of hardness, adhesion (crosscut = 0), and solvent resistance, with pendulum hardness values reaching 94–105 when catalyzed by MSA (methanesulfonic acid)/DBSA (dodecylbenzene sulfonate)/DTBP. These results demonstrate that the network architecture and thus the functional properties of itaconic acid–based renewable polyester coatings can be precisely controlled through targeted selection of catalysts and matrices. This approach offers a promising strategy for developing sustainable, high-performance bio-based coating materials.
