Acid-Responsive Anticorrosion Microcapsules for Self-Protecting Coatings

Dhawal R. Thakare, Thao M. Xiong, Ian L. Flueck, Ephraim G. Morado, Steven C. Zimmerman, Nancy R. Sottos

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

Encapsulated anticorrosion agents provide a suitable alternative to dispersion of metal-based compounds in protective polymeric coatings on metal substrates. Stimuli-responsive microcapsules enhance protection abilities by autonomously responding to corrosion-induced environmental changes, rather than relying on damage-induced mechanical stimuli. This work reports pH-responsive microcapsules with triggered release over a wide range of acidic pH values (pH < 6) and robust enough to be incorporated in commercial solvent-based epoxy coatings. The pH responsiveness is achieved by integrating acid labile ketals that undergo rapid hydrolysis within the cross-linked polyamide shell and readily release acetylenic diol or jojoba oil as the anticorrosive agent. The microcapsules are stable up to a temperature of 150 °C and provide long-term room temperature stability up to 3 months. Degradation and release kinetics of the microcapsules are quantified at various pH levels (1 ≤ pH ≤ 9) using 1H NMR and gas chromatography, respectively. Microcapsules exhibit complete release in under 5 min at pH 1 and ≈2 hours at pH 5, respectively. Coating performance is evaluated by electrochemical corrosion tests conducted in 5 wt% salt solutions with varying pH and concentration of the microcapsules in the coating. Inhibition efficiencies up to 70% are achieved in acidic saltwater solutions.

Original languageEnglish
Article number2100382
JournalMacromolecular Chemistry and Physics
Volume223
Issue number5
DOIs
StatePublished - 1 Mar 2022
Externally publishedYes

Keywords

  • acid-responsiveness
  • anticorrosion
  • corrosion
  • microcapsules
  • self-protecting coatings

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Polymers and Plastics
  • Organic Chemistry
  • Materials Chemistry

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