Responsive Colloidosomes with Triple Function for Anticorrosion.

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.

Encapsulation of emulsion droplets and nanoparticles in nanofibers as sustainable approach for their transport and storage.

HYPOTHESIS: Emulsions are metastable and can be destabilized by coalescence and Ostwald ripening, which lead to phase separation. Immobilizing emulsion droplets in a solid material shall improve their stability during storage. EXPERIMENTS: Miniemulsions and dispersions of nanocapsules are electrospun to immobilize colloids in polymer nanofibers. The nanofibers are dissolved after various period of time to re-disperse nanodroplets and nanocapsules. FINDINGS: The size of nanodroplets and nanocapsules are close to the size of the original colloids before electrospinning, meaning that the emulsion droplets are efficiently stored overtime in nanofibers. Entrapping droplets in nanofibers by electrospinning allows a reduction of weight and volume of the emulsion of up to 82%. This method is therefore beneficial for improving shelf-life of emulsions, decreasing storage volume, and decreasing energy consumption for transportation of emulsions.

Programming pH-responsive release of two payloads from dextran-based nanocapsules.

Controlled release of payloads such as drugs or corrosion inhibitors from nanocapsules is a prerequisite for their utilization. Indeed, premature leaching and contamination of the environment can be avoided. Herein, we investigate the pH-dependence of release kinetics of corrosion inhibitors from nanocapsules. Nanocapsules are formed by interfacial crosslinking of dextran derivatives in inverse miniemulsion and subsequently re-dispersed in aqueous solutions. Release kinetics are highly dependent on pH value and can be explained by a complex interplay involving swelling of nanocapsules shell, solubility of corrosion inhibitors, and electrostatic interactions between payloads and the shell.

Encapsulation and Release of Functional Nanodroplets Entrapped in Nanofibers.

A method is presented for preserving the structural integrity of nanodroplets produced by emulsification. Droplets of different hydrophobic liquids such as essential oils or monomers are produced by the miniemulsion process. The miniemulsions are then electrospun to yield dextran nanofibers entrapping the hydrophobic nanodroplets. The nanodroplets are then successfully redispersed by dissolving the nanofibers in water. Furthermore, it is shown that nanofibers can be used to store a monomer and a catalyst as healing agents for ring-opening metathesis polymerization. After dissolution, the healing agents are released and a self-healing reaction takes place. Embedding, storage, and release of emulsion nanodroplets is a promising method that avoids potential destabilization of droplets by coalescence or Ostwald ripening.