Progress in Organic Coatings最新文献

This research explores the physicochemical attributes of a fully bio-epoxy thermoset aimed at serving as an anti-corrosion coating for safeguarding carbon steel structures in marine environments. Throughout this investigation, various epoxy thermosets formulations, based on epoxidized soybean oil (ESO) and tannic acid (TA), were synthesized by adjusting the initial ratios of epoxide:hydroxyl groups (epoxy:OH). These formulations were subsequently applied onto carbon steel substrates and subjected to thermal curing at moderate temperatures (170 °C) to evaluate their anti-corrosion effectiveness using electrochemical impedance spectroscopy (EIS). The examination of the total impedance values derived from EIS Bode diagrams (>10⁶ Ω) revealed a notable anti-corrosion efficacy that endured over several months of immersion in 3.5 wt% NaCl solutions. In addition to electrochemical assessment, a rheological analysis was conducted to determine the optimal curing temperature for each formulation and to track the evolution of their mechanical properties throughout the curing process. Furthermore, the progression of corrosion at the coating-metal interphase was quantified using samples featuring artificially created notches to facilitate rapid water penetration, reaching the protected surface. Moreover, cross-cut and pull-off adhesion tests were conducted on coatings cured with various epoxide:hydroxyl ratios, yielding exceptional results on carbon steel substrates. Overall, a great potential for anti-corrosion protection has been demonstrated on the developed fully bio-based coatings with tuneable mechanical properties, regarding the initial component ratio, to reach the specific requirements for specific applications.

The burgeoning realms of artificial intelligence, the Internet of Things and 5G communication, have engendered a consistent increase in the demand for interlayer insulation materials featuring a reduced dielectric constant, thereby enhancing the signal transmission speed as large-scale integrated circuits progressively turn towards miniaturization and high integration. Polyimide has received tremendous attention as interlayer insulating material owing to the inherent advantages including excellent thermal and chemical stability, and mechanical strength. Thus far, endeavors aimed at diminishing the dielectric constant to low (<2.5) or even ultralow (≤2.2) levels of polyimide have attracted extensive interest. Herein, starting from a brief overview of the design principles of low dielectric materials, the latest research progress in the designation of intrinsic low dielectric polyimides, including fluorinated polyimides, polyimides with rigid and bulky structures, and other intrinsic low dielectric polyimides, has been thoroughly reviewed. Furthermore, the dielectric properties, water absorption capacity, and mechanical and thermal performances of different polyimides are elucidated. Finally, the key issues and challenges faced in the advancement of intrinsic low dielectric polyimides are elaborated, and the outlooks of the design of the materials are furtherly outlined. The primary objective of this paper is to acquire comprehensive and profound insights into intrinsic low dielectric polyimides, offering solid theoretical foundations and empirical references to guide future development of next-generation polyimides endowed with exceptional dielectric properties.

Catheter-associated urinary tract infections (CAUTIs) pose a significant clinical challenge, potentially resulting in complications such as bacteriuria and mortality. Developing coatings with antibacterial and antiadhesive properties for urinary catheters is essential to address these issues. In this study, a novel hydrogel coating composed of silver nanoparticles (Ag NPs), sodium alginate (SA), polyacrylamide (PAAm), and polyvinyl alcohol (PVA) was prepared on polydopamine (PDA)-modified latex urinary catheters using a simple dipping method. The Ag NPs were synthesized via an in-situ reduction of AgNO₃ with SA, eliminating the need for additional chemical reductants. The Ag NPs-SA-PAAm-PVA hydrogel-coated urinary catheter demonstrated superior antibacterial and antiadhesive characteristics compared to the bare urinary catheter. The antiadhesive properties of the hydrogel-coated urinary catheter were attributed to its hydrophilicity and lubricity, while the antibacterial effects were linked to the penetration of Ag NPs and Ag⁺ ions into bacterial structures, disrupting bacterial metabolism through the generation of reactive oxygen species (ROS) and free radicals upon attachment of Ag⁺ ions to cell walls and membranes. Furthermore, the hydrogel coatings exhibited remarkable mechanical properties, along with good biocompatibility and hemocompatibility. The exceptional antibacterial and antiadhesive properties of the hydrogel-coated urinary catheter hold promise for reducing CAUTIs.

Lignin with increased polyhydroxyl content (LOH) was prepared via a one-pot synthesis using enzymatically hydrolyzed lignin (EHL) as the raw material. The modified structure and hydroxyl content of LOH were analyzed using FT-IR, ¹H NMR, and ³¹P NMR. LOH was blended with zinc oxide (ZnO), polyester resin and hydroxyl alkyl amide (HAA) to prepare polyester powder coatings. The anti-UV properties of the coating were significantly enhanced by the addition of LOH and ZnO. The coating exhibits exceptional adhesion, rating at level 0, and achieves a pencil hardness of 7H. The gel time for the coating is 195 s, and it has a 5-degree Celsius increase in melting temperature, which greatly enhances its storage stability. Considering a range of factors, the formula LOH7.5 % has been identified as the optimal composition. The results of this study demonstrate an easy approach to developing sustainable lignin-based powder coatings with excellent properties.

Previous coatings or barrier films have failed to focus on the combined application of oxygen barrier and long-term corrosion protection. In this paper, a two-dimensional sheet filler KCB with triple functions of anti-corrosion, oxygen barrier and corrosion inhibition was prepared by growing cerium dioxide (CeO₂) on the surface of natural nanocontainer kieselguhr and adsorbing benzotriazole (BTA). Then applied KCB to epoxy resin (EP) to obtain EP/KCB composite coating. The hydroxyl group of CeO₂ improves the compatibility of EP with KCB. The hydrogen bonding between BTA and KC, and the adsorption at the Ce³⁺ defect sites turn KCB into an impermeable physical barrier, which can form an inert protective film at the interface after the BTA later release. The experimental data show that the O₂ GTR value of the EP/KCB5 composite coating is reduced by 35.88 % compared with that of the PET film. The |Z|_{0.01 Hz} value both are as high as 10¹¹ Ω·cm² after immersed in 3.5 wt% NaCl solution for four months and with 3.0 MPa pure oxygen for 7 days, showing excellent potential for long-term oxygen resistance and corrosion protection. EP/KCB5 composite coating has an adhesion up to 11.63 MPa. Moreover, the BTA released in KCB chelates with the metal substrate to form an inert protective film, which further improves the anti-corrosion performance of the composite coating and has a certain self-healing ability. In summary, the EP/KCB5 composite coating shows excellent comprehensive properties, providing a new solution for long-term oxygen barrier and corrosion protection.

Cathodic electrodeposition paints have been used for decades to protect automobile bodies and other metallic objects from corrosion. Nevertheless, it is still a major challenge to establish deposition models with a high degree of precision exclusively from both bath and application data. In recent years, the impact of the gas bubbles emerged during the painting procedure on the deposition behavior has become the focus of relevant studies. For the first time, in this work, the formation of gas bubbles and their detachment during the coating process are accurately recorded via buoyancy measurements. The evaluation of the results clearly shows the formation of more gas volume than should be formed according to Faraday's law. The excess gas volume is assumed to be due to the formation of carbon dioxide, being generated by alkaline hydrolysis of urethane groups during the deposition process. Furthermore, the influence of the layer of insulating gas bubbles on film formation could be clearly demonstrated. These results provide crucial insights for the development of more advanced and precise deposition models.

There has been extensive research on conductive hydrogels, however, the current lack of practical applications is a significant issue. The crucial challenge lies in effectively integrating conductive hydrogels into practical use. Here, a uniform multifunctional hydrogel was facilely fabricated by integrating nitrogen-doped carbon capsules (N-Cc) and g-C₃N₄ to PEO/PVA hydrogels (VECGNC). The introduction of a double network structure through carbon material endows the VECGNC hydrogel with exceptional mechanical strength (stress: 47.2 kPa; strain: 318 %) and high electrical conductivity (0.025 S cm⁻¹). And it showed a good linear relationship between the temperature and pressure difference. Taking advantage of these properties, a logic gate circuit capable of sensing external pressure changes and effecting corresponding adjustments was constructed. Moreover, the strain sensitivity hydrogel designed in this work is capable of intelligent new traffic lights. Our work offers novel insights and methodologies for the utilization of multifunctional hydrogels in multi-scenario temperature and strains ensing applications.

Polyelectrolyte multilayers (PEMs) have received significant attention across various fields, including biomedical, environmental, and food packaging, due to their cost-effectiveness, versatility, and accessibility. Utilizing the Layer-by-Layer approach (LbL), PEMs can be fabricated to coat solid surfaces like glass, metals, polymers, and composites. The interaction between polyelectrolytes, such as polysaccharides, proteins, amino-functionalized tannins, synthetic polymers, or their composites, often results in the assembly of PEMs in aqueous solutions with adjusted pH and ionic strength. This review presents the primary treatment methods for PEM assembly for substrates, encompassing plasma, chemical, and ultraviolet radiation treatments. The review predominantly focuses on macromolecules from renewable sources, particularly polysaccharides containing ionizable groups in their chains, such as carboxylate, sulfate, and protonated amine, employed in PEM fabrication. Durable PEMs physically stabilized by intra- and intermolecular interactions can be developed by selecting an appropriate strategy for substrate oxidation, following the selection and deposition of polyelectrolytes on the modified substrate surface. The substrate coated with the PEMs assumes specific physicochemical characteristics of the applied polyelectrolytes, such as antiadhesive, antimicrobial, anticoagulant, and binding capacity toward toxic metals or other pollutants. This review also explores PEM fabrication strategies, including conventional dipping, spray, and spin coatings, leading to the assembly of polyelectrolytes for diverse applications. This review also discusses the application of PEMs in various systems, such as drug delivery systems, scaffolds for wound healing, wound dressings, sensors, food packaging, and environmental remediation.

To address issues with traditional water-based polyurethane (WPU) leather finishing agents like soft, sticky films, poor water resistance, and slow drying speed, a green, environmentally friendly leather finishing agent was developed using cellulose acetate to modify WPU. Through emulsification of water-based cellulose acetate (WCDA) with WPU emulsion, a nanocomposite emulsion (WCDA/WPU) was created, exhibiting a flexible structure, small particle size, high hardness, rapid drying, water resistance, and strong adhesion the substrate. This agent has a high solid content, excellent mechanical properties, fast drying, and strong binding with leather, overcoming previous limitations. Its properties result from the synergistic advantages of its components, providing a superior alternative to traditional WPU leather finishing agents. The WCDA/WPU nanocomposite emulsion consists of small WPU particles in a large WCDA particle space, with an oil-in-water core-shell structure. At a ratio of 1:3 (WPU:WCDA), the emulsion has a solid content of 56.68 % and a particle size of 195.32 nm. The resulting film has excellent mechanical properties with an elongation at break of 618.45 %, a tensile strength of 9.77 MPa, and a B hardness. The wear rate is 0.983 %, and the drying time is 1.5 times faster than WPU. The film surface is compact and smooth, with a static water contact angle of 94.6°, enhancing hydrophobicity. When applied to leather finishing, the WCDA/WPU nanocomposite emulsion improves air and water permeability by 205.9 % and 40.1 % respectively. Water absorption rates decrease by 19.81 % at 0.25 h and 14.74 % at 24 h, indicating improved resistance to dry and wet friction. In conclusion, leather treated with WCDA/WPU nanocomposite emulsion outperforms traditional methods.

To facilitate versatile application of polyimide (PI) under harsh conditions, the PI-PDA@PSF@TO coating was successfully developed. The results illustrate the successful formation of PSF@TO microcapsules by encapsulating tung oil (TO) into polysulfone (PSF). After the modification of polydopamine (PDA), PDA@PSF@TO microcapsules exhibit superior dispersion within the coating compared to PSF@TO, resulting in a 16.8 % increase in tensile strength. Moreover, upon coating damage, the released TO can shield the samples in salt environment for a duration of 8 days. In comparison to PI, PI-PDA@PSF@TO coating exhibits a noteworthy decrease of 42.7 % in wear rate. Even after thermal oxidation, there is a noticeable reduction in the friction coefficient from 0.501 to 0.377, accompanied by a decrease in the wear rate from 6.33 × 10⁻⁷ mm³N⁻¹ m⁻¹ to 3.31 × 10⁻⁷ mm³N⁻¹ m⁻¹. This improvement contributes to two factors: (I) The PDA@PSF@TO microcapsules, developed by PSF and PDA, achieves the stable storage of TO in PI. (II) The release of TO forms protective layers, which compensate for defects and provide excellent tribological properties, thereby demonstrating the self-lubrication and self-healing characteristics.