Self-healing and self-strengthening dual-function polyelectrolytes coating for corrosion protection of titanium sheet

A polyelectrolytes coating with self-healing and self-strengthening dual-function was fabricated on the titanium sheet for anticorrosion studies in fluorine-containing artificial saliva. The coating contains a polydopamine bottom film and 2-hydroxypropyltrimethyl ammonium chloride chitosan and sodium alginate multilayers. The incorporated polydopamine bottom film was modified to assure the adhesion of the polyelectrolytes coating on the titanium sheet. Based on the scratch assay, there are two stages for the scratched coating immersed in fluorine-containing artificial saliva: healing and strengthening. Results exhibited that the coating possesses a remarkable self-healing property in the early-stage immersion due to the swollen polyelectrolytes migrating to the scratched region and the calcium cations of the corrosive medium as an ionic crosslinker intercalated in the swollen polyelectrolytes forming calcium alginate and filling the micro-scale scratch. During the later-stage immersion, the self-healing coating showed excellent self-strengthening performance originating from the formation of the more and more compact film with calcium cations intercalated. This research provides an effective strategy to prolong the service life and improve corrosion performance for the implants in the human body environments.