Effect of concentration of DOC loaded TiO ₂ nanotubes on the corrosion behavior of smart coatings

The present work focuses on synthesis and characterization of novel polymeric based smart coatings containing various amount of titania nanotubes (TiO ₂ ) encapsulated with dodecylamine (DOC). The novelty of the current research work resides on the fact that the encapsulation of TiO ₂ nanotubes with DOC and its inhibition effect in polymeric smart coatings have not been previously reported. Towards this direction, TiO ₂ nanotubes with an average size of ⁓10–15 nm (as confirmed by scanning electron microscope (SEM) and transmission electron microscope (TEM) analysis) were synthesized through a hydrothermal process and were then impregnated with DOC. Various contents of the encapsulated TiO ₂ nanotubes (1, 3 and 5 wt%) were thoroughly dispersed into the epoxy matrix and the resulting composites were then applied on a cleaned steel substrate using doctor blade technique to develop smart coatings. Fourier-transform infrared spectroscopy (FTIR) analysis confirms the impregnation of TiO ₂ nanotubes with DOC. The encapsulated amount of DOC in TiO ₂ nanotubes was estimated by the thermogravimetric analysis (TGA). The UV–vis spectroscopy study demonstrates time dependent self-release of encapsulated DOC from the TiO ₂ nanotubes in response to pH change of the corrosive medium. TGA and FTIR analyses also indicate that different amounts of encapsulated TiO ₂ nanotubes dispersed into smart coatings do not degrade their structural and thermal properties. Moreover, a decrease in the corrosion rate of smart coatings with increasing amount of encapsulated TiO ₂ nanotubes in the EIS analysis confirms their superior anticorrosive performance. This improvement in corrosion resistance can be attributed to the efficient and high amount of DOC released from the encapsulated TiO ₂ nanotubes. A decent improvement of corrosion resistance make these smart coatings attractive for industrial applications.