Self-Healing Coatings Based on Halloysite Clay Polymer Composites for Protection of Copper Alloys

Abstract

Halloysite clay nanotubes loaded with corrosion inhibitors benzotriazole (BTA), 2-mercaptobenzimidazole (MBI), and 2-mercaptobenzothiazole (MBT) were used as additives in self-healing composite paint coating of copper. These inhibitors form protective films on the metal surface and mitigate corrosion. Mechanisms involved in the film formation have been studied with optical and electron microscopy, UV-vis spectrometry, and adhesivity tests. Efficiency of the halloysite lumen loading ascended in the order of BTA < MBT < MBI; consequently, MBI and MBT halloysite formulations have shown the best protection. Inhibitors were kept in the tubes buried in polymeric paint layer for a long time and release was enhanced in the coating defects exposed to humid media with 20-50 h, sufficient for formation of protective layer. Anticorrosive performance of the halloysite-based composite acrylic and polyurethane coatings have been demonstrated for 110-copper alloy strips exposed to 0.5 M aqueous NaCl for 6 months.

Dodecylamine-Loaded Halloysite Nanocontainers for Active Anticorrosion Coatings

“…These results are in agreement with those already reported in the literature Lvov et al, 2008;Shchukin et al, 2008;Abdullayev et al, 2013;Snihirova et al, 2013). After 8 h of immersion (Figure 8B), the coating self-healing has occurred and achieved the initial coating protective properties due to the increasing of impedance …”

Covalently modified halloysite clay nanotubes: synthesis, properties, biological and medical applications

“…Depending on the deposit the halloysite dimensions can vary. Generally HNTs have a length in the range of 0.2-1.5 mm, while the inner and outer diameters of the tubes are in the ranges of 10-30 nm and 40-70 nm, respectively 12,16,17 (Fig. 3).…”

Escalating Applications of Halloysite Nanotubes

“…For the HNTs-HPC nanocomposite films an increase in the water contact angle was observed 49 . HNTs are a good candidate for self healing anticorrosion coating formulations 8,[60][61][62] . Polyurethane and acrylic paints doped with HNTs laden with benzotriazole, 2-mercaptobenzimidazole, and 2-mercaptobenzothiazole corrosion inhibitors produce self-healing nanocomposites coatings for copper 62 .…”

“…Furthermore, the chitosanand PEI-coated HNTs exhibit show a radically reduced release comparatively to the uncoated HNTs. Other active agents like self healing 62 anticorrosion 60 and antimicrobial agents and proteins and DNA 71 can be laden for continued release. HNTs are used for persistent release of drugs for example the use of diltiazem HCl as a sculpt drug which is cationic in nature helps in binding with HNTs faces and its high solubility facilitates the filling of drug into lumen of HNTs but due to high diffusion of diltiazem it is hard to gain sufficient prolong delivery.…”