abstract
The present paper reports on the development of new sensing active coating on the basis of nanocontainers containing pH-indicating agent. The coating is able to detect active corrosion processes on different metallic substrates. The corrosion detection functionality based on the local colour change in active cathodic zones results from the interaction of hydroxide ions with phenolphthalein encapsulated in mesoporous nanocontainers which function as sensing nanoreactors. The mesoporous silica nanocontainers are synthesized and loaded with pH indicator phenolphthalein in a one-stage process. The resulting system is mesoporous, which together with bulkiness of the indicator molecules limits their leaching. At the same time, penetration of water molecules and ions inside the container is still possible, allowing encapsulated phenolphthalein to be sensitive to the pH in the surrounding environment and outperforming systems when an indicator is directly dispersed in the coating layer. The performed tests demonstrate the pH sensitivity of the developed nanocontainers being dispersed in aqueous solutions. The corrosion sensing functionality of the protective coatings with nanocontainers are proven for aluminium-and magnesium-based metallic substrates. As a result, the developed nanocontainers show high potential to be used in a new generation of active protective coatings with corrosion-sensing coatings.
keywords
PHENOLPHTHALEIN
subject category
Science & Technology - Other Topics; Materials Science; Physics
authors
Maia, F; Tedim, J; Bastos, AC; Ferreira, MGS; Zheludkevich, ML
our authors
António Alexandre Cunha Bastos
Junior Researcher
Frederico Calheiros Maia
PhD Student
João Tedim
Associate Professor
Mário Guerreiro Silva Ferreira
Retired Professor
Mikhail Zheludkevich
Invited Principal Researcheracknowledgements
FM and JT thank FCT for PhD grant SFRH/BD/72663/2010 and post-doc grant SFRH/BPD/64335/2009, respectively.