Enhancing Self-Healing and Adhesion Bonding Properties: Investigating the Promising Potential of Ce-ZIF8 MOF Hybrid Thin Films as pH-Responsive Nanocoatings.

Further modification of the pre-treated steel surface with cerium conversion coating was performed using a novel porous coordination polymer (PCP) based on zeolitic imidazole framework-8 (ZIF8) in order to reduce the defect and disorders of the surface. The treated mild steels (MS) with Ce (MS/Ce) and Ce-ZIF8 (MS/Ce-ZIF8) were characterized by the GIXRD, Raman, and FT-IR, and via contact angle and FE-SEM, their surface features were investigated. The protection performance of the samples against corrosion was evaluated in the saline solution media using electrochemical impedance spectroscopy (EIS, in the long term) and polarization tests. The results evidenced that applying the ZIF8 nanoparticles onto the Ce-treated steel surface increased the total resistance value after 24 h of immersion (49.47%). Afterward, the ZIF8-modified coating (MS/Ce and MS/Ce-ZIF8) impact on the epoxy coating protection function was characterized by EIS (in the scratched form), salt spray (5 wt % salts), cathodic disbonding (at 25 °C), and pull-off tests. The EIS outcomes of the scratched coatings proved approximately a 51.29% increase in Rt of the MS/Ce-ZIF8/EC sample compared with the MS/EC sample after 24 h of immersion. The cathodic disbonding test results after 24 h of exposure revealed that the delamination area of the coating decreased in the modified sample, and the delamination radius of the epoxy coating was about 4.78, 2.96, and 2.0 mm for the MS/EC, MS/Ce/EC, and MS/Ce-ZIF8/EC samples, respectively.

Design of Nacre-Inspired 2D-MoS2 Nanosheets Assembled with Mesoporous Covalent Organic Frameworks (COFs) for Smart Coatings.

High loading capacity and smart release of inhibitors are the first and foremost characteristics of nanocontainers, which play a pivotal role in metal active corrosion protection. The present work explores the development of novel protective nanocontainers based on recently emerged covalent organic frameworks (COFs). These highly porous frameworks with large surface area, outstanding thermomechanical properties, low density, and ease of functionalization are used as nanocontainers. On the other hand, molybdenum disulfide (MoS2), a state-of-the-art 2D layered compound with a sheetlike structure, was utilized thanks to its excellent barrier properties. However, these lamellar structures suffer a high agglomeration tendency in polymeric matrices. Therefore, we developed a novel hybrid nanocontainer, inspired by natural nacre, by an in situ growth of COF on MoS2 to improve the stability and provide a high inhibitor loading capacity. The porous and nitrogen-rich structure of COF made it a good carrier to adsorb europium cations as inorganic inhibitors and release them on demand by pH changes to suppress the electrochemical reactions. The as-synthesized nanoplatforms were used as pH-responsive fillers in the epoxy resin. The nanocomposite coatings showed almost 50 kΩ cm2 total resistance and high impedance values (1011 Ω cm2) even after 77 days of immersion. Moreover, salt spray analysis depicted the smallest amount of rust and corrosion product after 31 days in the filled nanocomposite coating. Cathodic delamination and pull-off outcomes denoted that the filled coatings with the as-synthesized nanofiller showed the smallest cathodic delamination radius (3.41 mm) and lowest adhesion loss (24%) compared to the neat epoxy (7.55 mm and 46.7%). As such, the highly porous modified MoS2 nanosheets are considered promising alternatives in a wide range of applications with anticorrosion properties.

Rising of MXenes: Novel 2D-functionalized nanomaterials as a new milestone in corrosion science - a critical review.

Corrosion is a natural process between a metal and its environment that can gradually cause catastrophic damage to the metal equipment, which would have economic implications. Consequently, several protective methods have been utilized to prevent metals from severe degradation. Organic polymeric coatings have been widely used as the most convenient and cost-effective method to boost metals' anti-corrosion properties. Nonetheless, these coatings have a significant amount of solvent, resulting in shrinkage and micro defects in the films during the curing process. Many studies have verified that transition metal carbides/nitrides (MXenes) can form a "labyrinth effect" in the polymeric coatings due to their "nano-barrier effect". Furthermore, based on their sheet-like structures, they can considerably cover the surface defects of the polymeric films. Therefore, the penetration of corrosive elements can be substantially curbed. It is the first review that specifically focused on the new family of 2D nanomaterials, i.e., MXenes, and discussed their applications in corrosion protection systems. The MXenes' pros and cons in the polymeric matrixes as nanofillers will be clarified. Moreover, the synthesis and functionalization methods of the MXenes, their applications, and corrosion protection mechanism will be explored. Subsequently, the MXenes' superiority over other 2D nanomaterials will be highlighted while their future perspectives and industrial applications will be predicted.

Designing Hybrid Mesoporous Pr/Tannate-Inbuilt ZIF8-Decorated MoS2 as Novel Nanoreservoirs toward Smart pH-Triggered Anti-corrosion/Robust Thermomechanical Epoxy Nanocoatings.

For the first time, organic tannic acid (TA) molecules and then inorganic praseodymium (Pr) cations as corrosion inhibitors were successfully loaded into a zeolitic imidazolate framework (ZIF8)-type porous coordination polymer (PCP) decorated on molybdenum disulfide, MoS2, (MS)-based transition metal dichalcogenides (TMDs) to create novel hybrid mesoporous Pr/TA-ZIF8@MS nanoreservoirs. Thereafter, the hybrid nanoreservoirs were embedded into the epoxy matrix for the preparation of smart pH-triggered nanocoatings. Characterizations of the Pr/TA-ZIF8@MS nanoreservoirs via Fourier transform infrared (FT-IR), X-ray diffraction (XRD), thermogravimetric (TG), Brunauer-Emmett-Teller (BET), and field emission-scanning electron microscopy (FE-SEM)/energy-dispersive X-ray spectroscopy (EDS) experiments confirmed the fabrication of mesoporous structures comprising Pr/TA interfacial interactions with ZIF8-decorated MS nanoplatelets possessing high thermal stability and compact/dense configuration features with a framework reorientation. A remarkable smart release of the inhibited cations (Pr3+ and Zn2+) in the presence of inbuilt TA at both acidic and alkaline media was achieved under inductively coupled plasma (ICP) examination. The superior pH-triggered self-healing inhibition through the smart controlled-release of Pr, tannate, Zn, and imidazole inhibited species/complexes from EP/Pr-TA-ZIF8@MS via ligand exchange was obtained from electrochemical impedance spectroscopy (EIS) assessments of the scratched coatings during 72 h of saline immersion. In addition, the long-term barrier-induced corrosion prevention (log |Z|10 mHz = 10.49 Ω·cm2 after 63 days) of the EP/Pr-TA-ZIF8@MS was actualized. Moreover, efficient increments of the coating cross-link density (56.45%), tensile strength (63.6%), and toughness value (56.5%) compared to the Neat epoxy coating revealed noticeable thermomechanical properties of the EP/Pr-TA-ZIF8@MS.

Ultrastable Porous Covalent Organic Framework Assembled Carbon Nanotube as a Novel Nanocontainer for Anti-Corrosion Coatings: Experimental and Computational Studies.

Covalent organic frameworks (COFs) have been proposed as a wholly organic architecture sharing high crystallinity, porosity, and tuneability. Moreover, they exhibit highly stable structures against harsh chemical environments, including boiling water, strong acids and bases, and oxidation and reduction conditions, making them good candidates for extreme conditions. For the first time, a porous COF structure based on terephthalaldehyde and melamine was synthesized and employed as a novel nanocontainer for hosting corrosion inhibitors to provide a coating with superior active/passive anti-corrosion properties. In this study, the multi-walled carbon nanotube was utilized as a platform for growing COF (CC) to improve the coating's barrier and thermo-mechanical properties. The zinc cations were loaded into the CC structure (called CCZ) as one of the most promising inhibitors for mild steel. The COF-based nanoparticles' characterization was done by Fourier transform infrared, Raman, X-ray diffraction, thermogravimetric analysis, Brunauer-Emmett-Teller, field emission scanning electron microscopy, and transmission electron microscopy (TEM) techniques. Moreover, the Density functional theory modeling and molecular dynamics simulation quantitatively highlighted the adsorption propensity of the investigated COF structures onto the oxidized CNT-based nanostructures and the interactions of epoxy with these nanostructures. The CCZ nanoparticles (NPs) showed 75% inhibition efficiency in saline solution and 418 ppm zinc ions release after 24 h at acidic pH. The CCZ/EP coating revealed the smart release of inhibitor for 24 h and represented excellent barrier properties after 9 weeks of immersion in saline solution. In terms of mechanical properties, the elastic modulus values derived from the dynamic mechanical thermal analyzer were enhanced by 107 and 137% in CC/EP and CCZ/EP samples compared to the neat epoxy. Furthermore, the yield stress and breakpoint elongation were strengthened by 102 and 63% for the CC/EP sample, respectively. Finally, the highest pull-off adhesion strength in dry (8.53 MPa) and wet (2.7 MPa) conditions, along with the lowest adhesion loss (68.3%), was related to the CCZ/EP sample.

Stachys byzantina extract: A green biocompatible molecules source for graphene skeletons generation on the carbon steel for superior corrosion mitigation.

The presence of bio-active compounds in Stachys byzantina (SB) extract has made it a powerful source of green inhibitors in controlling steel corrosion. In this study, it has been attempted to create a highly durable corrosion protective film on the surface of the metal with SB and divalent zinc (II) cations and investigated them by Electrochemical Impedance Spectroscopy (EIS) and Potentiodynamic polarization (PP) tests, and surface analysis methods. EIS results show that after 24 h of placing the steel samples in 3.5% NaCl solution containing 700 SB - 300 ZN, the synergistic corrosion inhibition behavior was about 92%. Besides, the results of the PP demonstrated a significant reduction of the icorr. Furthermore, surface analyses such as Field Emission Scanning Electron Microscopy/Energy Dispersive X-ray Spectroscopy (FE-SEM/EDS) and Atomic Force Microscopy (AFM) images illustrated the low metal surface degradation, which indicates that the mix of SB and Zn caused a protective layer creation on the surface, especially for SB 700 - Zn 300. Also, new compounds of graphitic materials' structure were made using SB extract which is a natural-based chemical, and investigated by Fourier-Transform Infrared Spectroscopy (FTIR) test, Grazing Incidence X-ray Diffraction (GIXRD) technique, Ultraviolet-visible spectroscopy (UV-Vis) analysis, and Raman spectroscopy.

Synthesis of graphene oxide nanosheets decorated by nanoporous zeolite-imidazole (ZIF-67) based metal-organic framework with controlled-release corrosion inhibitor performance: Experimental and detailed DFT-D theoretical explorations.

For the first time, the zeolite-imidazole (ZIF-67) framework, a new subfamily of metal-organic frameworks (MOFs), is synthesized on the graphene oxide (GO) platform. Co2+ (as a central atom) and 2-methylimidazole (as organic ligands) were assembled to fabricate ZIF-67/GO NPs for providing epoxy-based anti-corrosion coatings with both active (self-healing) and passive (barrier) performance. Also, the ZIF-67/GO NPs were modified by 3-Aminopropyl triethoxysilane (APS) to improve the particles compatibility with the epoxy matrix and control their solubility in saline media. The FE-SEM, FT-IR, UV-Vis, Raman, TGA, and low-angle XRD techniques were used to prove the successful ZIF-67 particles growth onto the GO platforms. Tafel (potentiodynamic) polarization test demonstrated that the ZIF-67/GO@APS NPs could protect the surface of steel through mixed anodic/cathodic type (O2 reduction/Fe oxidation) mechanisms and the corrosion current density of the iron sample decreased to 1.41 µA·cm-2. Interestingly, the epoxy coatings containing ZIF-67/GO and ZIF-67/GO@APS particles revealed long-term corrosion protection durability and outstanding self-healing anti-corrosion performance, which were well studied via EIS, salt spray, cathodic delamination, and pull-off techniques. The impedance value at the lowest frequency for the coating containing ZIF-67/GO@APS after 50 days decreased from 10.7â€¯Ω·cm2 to 10.2â€¯Ω·cm2 that showed the lowest reduction among the studied samples.

A green assisted route for the fabrication of a high-efficiency self-healing anti-corrosion coating through graphene oxide nanoplatform reduction by Tamarindus indiaca extract.

The major focus of the recent studies in metals corrosion protection field is now the development of non-hazardous and eco-friendly materials as effective substitutes for some of the well-known conventional toxic/unsafe inhibitors based on chromate, lead, phosphate, and azole derivatives. The present work focuses on the sustainable development of an intelligent self-healing anticorrosion coating using nanocarriers based on the graphene oxide nanoplatform-Tamarindus indiaca extract-Zn2+ (GON-Ti.E-Zn)-through a facile green assisted route. The GON-Ti.E-Zn nanocarrier was introduced into the epoxy ester film (EEF) to achieve a smart barrier/self-healing anti-corrosive property. To this end, a couple of characterization tests, including FT-IR, UV-vis, XRD, TGA, and Raman spectroscopy, have been carried out to investigate the GON-Ti.E-Zn nanocarrier structure/composition. The effectiveness of the anti-corrosion performance of the established coatings was confirmed by EIS, FE-SEM, and accelerated salt spray (SS) test. The observation of the high impedance magnitude at low-frequency (47.14 Gohm cm2 after 5 weeks immersion in saline solution) for the un-defected EEF and significant impedance enhancement for the defected EEF including GON-Ti.E-Zn nanocarrier confirmed the excellent barrier effect of GO and synergistic behavior and noticeable corrosion inhibition impact of Tamarindus indiaca along with the zinc cations on the mild steel corrosion mitigation.

Production of an environmentally stable anti-corrosion film based on Esfand seed extract molecules-metal cations: Integrated experimental and computer modeling approaches.

This study aims at finding a suitable alternative for traditional and hazardous organic/inorganic corrosion inhibitors. In this study, the aqueous extract of Esfand seed (ESE) was used as a unique green source of nitrogen-based organic compound with great capability of the steel corrosion inhibition in a saline solution. Surface and electrochemical analyses were carried out by Ultraviolet-visible spectroscopy (UV), Fourier-transform infrared spectroscopy (FT-IR), Grazing incidence X-ray diffraction (GIXRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), atomic force microscopy (AFM), electrochemical impedance spectroscopy (EIS), and polarization methods. Furthermore, the adsorption of inhibitors on the steel surface was explored by Monte Carlo (MC), molecular dynamics (MD) and quantum mechanics (QM) methods. The electrochemical studies established the effectiveness of the zinc cations addition to the ESE containing solution on its inhibition efficiency. The sample inhibited by 300 ppm ESE + 700 ppm Zn showed the highest anti-corrosion properties. The inhibition efficiency of this sample was reached 98.8% after 264 h which is much higher than those reported in the previous studies. QM computations proved the formation of complexes via donor-acceptor action. MC and MD simulations supported the inhibitors adsorption on the steel.