Hybrid Halloysite Nanotubes as Smart Carriers for Corrosion Protection

Abstract

Novel hybrid halloysite nanotubes (HHNTs) were developed and used as smart carriers for corrosion protection of steel. For this purpose, as-received halloysite nanotubes (HNTs) were loaded with a corrosion inhibitor, imidazole (IM), by vacuum encapsulation. In the next step, a layer by layer technique was employed to intercalate another inhibitor, dodecylamine (DDA), in the polyelectrolyte multilayers of polyethylenimine and sulfonated polyether ether ketone, leading to the formation of HHNTs. During this process, IM (5 wt %) was successfully encapsulated into the lumen of HNTs, while DDA (0.4 wt %) was effectively intercalated into the polyelectrolyte layers. Later, the HHNTs (3 wt %) were thoroughly dispersed into the epoxy matrix to develop smart hybrid self-healing polymeric coatings designated as hybrid coatings. For a precise evaluation, epoxy coatings containing as-received HNTs (3 wt %) without any loading denoted to as reference coatings and modified coatings containing HNTs loaded with IM-loaded HNTs (3 wt %) were also developed. A comparative analysis elucidates that the hybrid coatings demonstrate decent thermal stability, improved mechanical properties, and promising anticorrosion properties compared to the reference and modified coatings. The calculated corrosion inhibition efficiencies of the modified and hybrid coatings are 92 and 99.8%, respectively, when compared to the reference coatings. Noticeably, the superior anticorrosion properties of hybrid coatings can be attributed to the synergetic effect of both the inhibitors loaded into HHNTs and their efficient release in response to the localized pH change of the corrosive medium. Moreover, IM shows an active release in both acidic and basic media, which makes it suitable for the protection of steel at the early stages of damage, while DDA being efficiently released in the acidic medium may contribute to impeding the corrosion activity at the later stages of deterioration. The tempting properties of hybrid coatings demonstrate the beneficial role of the development of novel HHNTs and their use as smart carriers in the polymeric matrix for corrosion protection of steel.

Effectiveness of Epoxy Coating Modified with Yttrium Oxide Loaded with Imidazole on the Corrosion Protection of Steel

“…In contrast, weight loss of Y 2 O 3 /IMD observed in three stages of TGA spectra. In the first stage, a sharp weight loss occurs from room temperature (28 °C) to 200 °C, due to the imidazole decomposition [ 31 ]. In the second stage (201 °C to 400 °C), weight losses occur due to removing some residual compounds of imidazole until its complete decomposition.…”

“…A comparative trend with respect to immersion times at different pH values (2, 7 and 11) is presented in Figure 5d. The presence of inhibitor is confirmed in all different pH conditions (acidic, neutral, and basic) but it shows increased absorbance intensity in acidic medium as compared to basic and neutral [31]. The standard solution curve equation (Supplementary Figure S4) was used to evaluate the release percentage of imidazole from the Y 2 O 3 and depicted in Figure 6.…”

“…The impedance values for the reference (Y 2 O 3 ) and inhibited coatings (Y 2 O 3 /IMD) at different immersion times were used to calculate the inhibition efficiency (I.E %) [31]-Table 1.…”

Challenges and Opportunities of Self‐Healing Polymers and Devices for Extreme and Hostile Environments

“…In addition, the surface coating with multilayer of polyelectrolytes improved the dispersion of the halloysite nanocontainers. [ 65 ]…”

Fabrication of active corrosion protection waterborne polyurethane coatings using cerium modified palygorskite nanocontainers

“…Furthermore, it only releases inhibitors on demand and achieves anti‐corrosion function. Some studies reported CeO 2 , 19,20 halloysite, 21–25 silica, 26–29 and ZnO nanoparticles, 30 can be used as nanocontainers to store and release inhibitors. Unfortunately, the complicated nanocontainer preparation or inhibitor storage process extremely hindered their industrial application.…”