@article{fa3eeb1617834da48fef626e08d5b96f,
title = "Acid-Responsive Anticorrosion Microcapsules for Self-Protecting Coatings",
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.",
keywords = "acid-responsiveness, anticorrosion, corrosion, microcapsules, self-protecting coatings",
author = "Thakare, {Dhawal R.} and Xiong, {Thao M.} and Flueck, {Ian L.} and Morado, {Ephraim G.} and Zimmerman, {Steven C.} and Sottos, {Nancy R.}",
note = "Funding Information: D.R.T. and T.M.X. contributed equally to this work. D.R.T. was supported by a PPG‐MRL Graduate Assistantship Award. T.M.X. and E.G.M. were supported by the National Science Foundation (NSF CHE‐1709718). Additional support for I.L.F. was provided by the Illinois Scholars Undergraduate Research (ISUR) Program. This work was conducted in part at the Microscopy Suite of the Beckman Institute for Advanced Science and Technology at the University of Illinois at Urbana‐Champaign (UIUC‐BI‐MS). The authors thank D. Olson, N. Duay, and the School of Chemical Sciences NMR (SCS‐NMR‐UIUC) Lab for access to NMR instrumentation and their technical support, and Prof. David Sarlah for providing access to the Shimazdu GC‐2010. The Bruker 500‐Mz NMR spectrometer was obtained with the financial support of the Roy J. Carver Charitable Trust, Muscatine, Iowa, USA. The authors acknowledge Dr. Odarczenko for his help with EC test cell schematic. The authors also thank Carboline for providing the phenolic resin coating. Funding Information: D.R.T. and T.M.X. contributed equally to this work. D.R.T. was supported by a PPG-MRL Graduate Assistantship Award. T.M.X. and E.G.M. were supported by the National Science Foundation (NSF CHE-1709718). Additional support for I.L.F. was provided by the Illinois Scholars Undergraduate Research (ISUR) Program. This work was conducted in part at the Microscopy Suite of the Beckman Institute for Advanced Science and Technology at the University of Illinois at Urbana-Champaign (UIUC-BI-MS). The authors thank D. Olson, N. Duay, and the School of Chemical Sciences NMR (SCS-NMR-UIUC) Lab for access to NMR instrumentation and their technical support, and Prof. David Sarlah for providing access to the Shimazdu GC-2010. The Bruker 500-Mz NMR spectrometer was obtained with the financial support of the Roy J. Carver Charitable Trust, Muscatine, Iowa, USA. The authors acknowledge Dr. Odarczenko for his help with EC test cell schematic. The authors also thank Carboline for providing the phenolic resin coating. Publisher Copyright: {\textcopyright} 2022 Wiley-VCH GmbH",
year = "2022",
month = mar,
doi = "10.1002/macp.202100382",
language = "English (US)",
volume = "223",
journal = "Macromolecular Chemistry and Physics",
issn = "1022-1352",
publisher = "Wiley-VCH",
number = "5",
}