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In the context of high-pressure, high-temperature (HPHT) conditions resembling those in the oil and gas industry, the performance of epoxy-siloxane hybrid coatings is investigated. Neat amine-cured epoxy novolac (EN) coatings exhibit drawbacks under these conditions, including softening upon exposure to hydrocarbons, leading to underfilm corrosion triggered by CO 2 gas and seawater ion diffusion. To address these issues, two hybrid coatings, long-chain epoxy-terminated polydimethylsiloxane-modified EN (EN-EPDMS) and short-chain 3-glycidyloxypropyltrimethoxysilane-modified EN (EN-GPTMS), are assessed in HPHT environments. Both hybrids mitigate drawbacks observed in neat EN, with EN-GPTMS completely eliminating them due to the chemical inertness of inorganic siloxane networks. While EN-EPDMS exhibits a higher glass transition temperature than EN-GPTMS, it is susceptible to rapid gas decompression due to its lengthy and flexible siloxane backbone, resulting in unburst blisters. Conversely, EN-GPTMS demonstrates superior performance in HPHT environments, highlighting its potential for effective corrosion protection in harsh conditions encountered by the oil and gas industry., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

A comparative study between the leaching behavior of inhibitive ions from conventionally pigmented and smart (with encapsulated pigments) epoxy coatings has been conducted. Leaching of calcium phosphate as an inhibitive pigment from epoxy coatings was tested in 3.5 wt % NaCl solution. The results showed that pigment encapsulation contributed to a more uniform and stable coating microstructure based on the Scanning Electron Microscopy-Energy-Dispersive X-ray Spectroscopy (SEM-EDX) analysis and a higher leaching rate of the inhibitive pigment via the Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) analysis, thereby enhancing both the active corrosion protection and the barrier properties of the coating film. This was further verified by the Electrochemical Impedance Spectroscopy (EIS) measurements. After 7 days of immersion in 3.5 wt % NaCl solution, the coating resistance of the smart epoxy coating with mesoporous silica nanoparticle encapsulated calcium phosphate (MSN-CP3%) was 2 × 10 9 Ω·cm 2 compared to 1.1 × 10 6 Ω·cm 2 and 2.6 × 10 6 Ω·cm 2 for the conventional epoxy coatings pigmented with 3 wt % and 5 wt % calcium phosphate (CP3% and CP5%), respectively., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

The effect of adding 0.5 wt % zinc fibers on the anticorrosion performance of zinc-rich epoxy (ZRE) coatings with 85, 75, and 65 wt % of zinc dust was investigated. The salt spray testing, scanning electron microscopy, open circuit potential, and electrochemical impedance spectroscopy measurements were used to characterize the corrosion protection performance of coatings. The results indicate that the ZRE coating containing 85 wt % zinc dust showed superior cathodic protection, while the coating with 65 wt % zinc dust provided neither cathodic protection nor good barrier protection. No significant improvement in the anticorrosion performance was observed for both coatings with the addition of 0.5 wt % zinc fibers. In contrast, the ZRE coating containing 75 wt % zinc dust, which provided short-term cathodic protection followed by barrier protection, showed remarkably improved anticorrosion performance with the addition of zinc fibers., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

Silica aerogel-encapsulated biocide crystals can potentially enhance the protection efficiency of antifouling coatings, thereby lowering the impact on nontarget aquatic life. In the present study, copper pyrithione (CuPT) crystals are encapsulated by silica aerogel to obtain loadings of 50-80 wt % CuPT. For optimal design of the heterogeneous particles and mapping of the underlying biocide release mechanisms, the aerogel-encapsulated biocide crystals are characterized by scanning (transmission) electron microscopy, energy-dispersive X-ray spectroscopy, thermal gravimetric analysis, mercury intrusion porosity, Brunauer-Emmett-Teller analysis, and light scattering. The microscopic examination demonstrates that the elongated CuPT crystals are encapsulated by a thin highly porous silica layer. When varying the CuPT loading of the aerogels, it is possible to tune the particle size, pore volume, and specific surface area of the aerogels. Furthermore, this study suggests that the hydrophilic aerogel-encapsulated CuPT, when used in antifouling coatings, attracts seawater and contributes to an efficient controlled release of active CuPT., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)