Multilevel Self-Healing Characteristics of Smart Polymeric Composite Coatings

Abstract

Smart polymeric composite coatings demonstrating multilevel self-healing characteristics were developed and characterized. The pHresponsive smart carriers were synthesized by loading halloysite nanotubes (HNTs) with the benzotriazole corrosion inhibitor (BTA) using the vacuum cycling method, referred to as (BTA-loaded HNTs). Similarly, mechanically triggered melamine urea-formaldehyde microcapsules encapsulated with the boiled linseed oil-self-healing agent (LO) denoted as (MUFMCs) having an average size of a ∼120 μm diameter with a wall thickness of ∼1.84 μm were synthesized by the in situ polymerization technique. The newly designed double-layered smart polymeric composite coatings (DLPCs) were developed by mixing 3 wt % BTA-loaded HNTs with epoxy and applying it on the clean steel substrate to form a primer layer. After its complete curing, a top layer of epoxy containing 5 wt % of MUFMCs was deposited on it. For an exact comparison, single-layer polymeric composite coatings (SLPCs) containing 3 wt % BTA-loaded HNTs were also developed. The Fourier transform infrared radiation spectra of MUFMCs and BTA-loaded HNTs indicate the existence of all desired functional groups, confirming the presence of loaded chemical species such as LO and BTA into the smart carriers. Thermogravimetric analysis (TGA) indicates that ∼18% BTA is successfully loaded into HNTs. Quantitative UV-spectroscopic analysis indicates a pH-responsive release of BTA from BTA-loaded HNTs, which is time-dependent, attaining its maximum value of ∼ 90% in an acidic medium after 30 h. Electrochemical impedance spectroscopy analysis conducted in 3.5 wt % NaCl solution at room temperature for different immersion times reveals that SLPC exhibits the maximum chargetransfer resistance (R ct ) of 55.47 GΩ cm 2 after the 7th day of immersion, and then, a declining trend is observed, reaching 26.6 GΩ cm 2 after the 9th day. However, in the case of DLPC, the R ct values show a continuous increment, attaining a maximum value of 82.11 GΩ cm 2 after the 9th day of immersion. The improved performance of DLPC can be ascribed to the efficient triggering of the individual carriers in the isolated matrices, resulting in the release of LO and BTA to form individual protective films at the damaged area due to the oxidative polymerization process and triazoles' ability of passive film formation on the substrate, respectively. The tempting self-healing properties of DLPCs justify their decent role for long-term corrosion protection in many industrial applications.

Even Incorporation of Nitrogen into Fe0 Nanoparticles as Crystalline Fe4N for Efficient and Selective Trichloroethylene Degradation

“…As a rule of thumb, a larger lattice constant means a larger interatomic distance, where the valence electrons tend to be released more readily, that is, a lower band energy gap and a faster electron transfer. , A similar phenomenon was also found in the sulfidation of Fe 0 when sulfur was incorporated into the Fe 0 BCC structure . This enlarged lattice is consistent with the result of the EIS measurement, which could assess the electron conduction performance of materials. , The Nyquist plot (Figure c) shows the smaller arc radii of the nitridated Fe 0 materials than that of nZVI (Figure c), suggesting their lower charge-transfer resistance . However, a limited difference in the arc radii was observed for the nitridated Fe 0 materials with different N contents, consistent with similar lattice constants (Figure b) and N speciation (Figure S4b) of these nitridated Fe 0 materials.…”

“…16 This enlarged lattice is consistent with the result of the EIS measurement, which could assess the electron conduction performance of materials. 56,57 The Nyquist plot (Figure 3c) shows the smaller arc radii of the nitridated Fe 0 materials than that of nZVI (Figure 3c), suggesting their lower charge-transfer resistance. 58 However, a limited difference in the arc radii was observed for the nitridated Fe 0 materials with different N contents, consistent with similar lattice constants (Figure 3b) and N speciation (Figure S4b) of these nitridated Fe 0 materials.…”

Synthesis of Mesoporous Silica Particles as Inhibitor Containers for Anticorrosive Applications

“…It is attributed to �C−H out of plane bending representing the BTA moiety. 42 The appearance of characteristic functional group peak of the inhibitor BTA in the spectra of BTA@MSP1 and BTA@MSP2 indicates successful incorporation of BTA into MSP. As expected, the peak appearing at 968 cm −1 only in BTA@ MSP1 and BTA@MSP2 spectra assigned to the band associated with the vibration of silanol groups (Si−O−H) 43 can be attributed to the water content from the synthesis process and are clearly not present in calcined particles MSP1 and MSP2.…”

Multilayered LDH/Microcapsule Smart Epoxy Coating for Corrosion Protection

“…Due to fewer defects and pores in the coatings in a multilayered coating system, the anti-corrosion property was improved . Hassanein et al developed a multilayered epoxy coating (DLPCs) with halloysite nanotubes loaded with benzotriazole reinforced in the epoxy coating as a prelayer and melamine urea formaldehyde microcapsules reinforced in the epoxy coating as a top layer . DLPCs showed a corrosion resistance of 4.19 GΩ cm 2 after 9 days of immersion in NaCl corrosive solution.…”