Responsive Colloidosomes with Triple Function for Anticorrosion

Abstract

Strategies for corrosion protection are required to prolong the life span of metallic structures used by the construction, aerospace, and transport industries. Currently, there are no coatings that can provide at the same time information about the corrosion status of the coated metal and protect the metal against corrosive species and mechanical damage. Herein, triple-functional microcarriers with functions of corrosion sensing, self-healing, and corrosion inhibition are produced and embedded in coatings to prolong the lifetime of metals and enhance the anticorrosion performance of coatings. The microcarriers are prepared by creating Pickering droplets loaded with a corrosion inhibitor and a healing agent and stabilized by silica nanocapsules containing thymol blue as corrosion sensor. The microcarriers are then embedded in a water-based polymer matrix coated on metal substrates. When the coating or metal is mechanically damaged, the healing agent is released from the droplets to hinder further corrosion of the metal. When the local pH value near the metal surface is changing by the generation of hydroxide ion due to the corrosion process, a change of color is detected as well as a release of corrosion inhibitor, leading to a significant decrease of corrosion rate of the coated metal.

Design of Nanostructured Protective Coatings with a Sensing Function

“…As shown in Figure , a layer of corrosion product appeared on coatings A141 and C241 within 6 h, whereas a weak fluorescence emission was observed without visible appearance of a layer of the corrosion product for coatings A151, A161, C351, and C361, indicating that corrosion had started but was not yet severe. Typical sensors for copper corrosion previously reported showed a change of optical properties at the scratched area in 2–8 h , and around 7 days for intact (non-scratched) coating …”

“…Thus, pH-sensitive dyes were employed for detecting corrosion and entrapped in micro- or nanoparticles ,,, and nanofibers . The change of pH value generated a significant change of color, ,− fluorescence intensity, or fluorescence resonance energy transfer . FITC is a dye displaying a pH-dependent fluorescence, which has a high fluorescence quantum yield (Φ 2 f = 0.93 at p K a 6.43) in aqueous solution (see Figure S1a).…”

“…In addition, an interesting feature to be introduced in coatings for anticorrosion is corrosion sensing so that metallic structures can be replaced before critical damage. , This has been achieved by encapsulating various dyes in particles ,,,− or fibers that were subsequently embedded in coatings. The coatings displayed then a change of color or an increase/decrease in fluorescence intensity upon change of pH value or the presence of metal ions as a consequence of the corrosion process.…”

Increased Stability of Polysaccharide/Silica Hybrid Sub‐Millicarriers for Retarded Release of Hydrophilic Substances

“…[27][28][29][30][31][32][33][34] Organic-inorganic hybrid structures are able to protect the encapsulated payloads from the surrounding environment and allow their release in a controlled manner. [35][36][37][38][39] In this work, a loaded organic-inorganic macrogel was prepared by ionotropic gelation, and its efficiency for entrapping hydrophilic molecules was investigated. Chitosan and alginate were used as the main polymer component, and silica was used as a structuring additive to reach a high encapsulation efficiency.…”

“…[ 27–34 ] Organic–inorganic hybrid structures are able to protect the encapsulated payloads from the surrounding environment and allow their release in a controlled manner. [ 35–39 ]…”