Abstract
Steel is prone to corrosion induced by chloride ions, which is a serious threat to reinforced concrete structures, especially in marine environments. In this work, we report a novel capsule-based self-recovery system that utilizes chloride ions as a trigger. These capsules, which are functionalized via a smart response to chloride ions, are fabricated using a silver alginate hydrogel that disintegrates upon contact with chloride ions, and thereby releases the activated core materials. The experimental results show that the smart capsules respond to a very low concentration of chloride ions (0.1 wt%). Therefore, we believe that this novel capsule-based self-recovery system will exhibit a promising prospect for self-healing or corrosion inhibition applications.
Highlights
Chloride ions provide a stable trigger for responsive capsules
The chloride ions triggering process was recorded in a movie (Supplementary movie 1)
We have introduced a new concept: chloride ions responsive capsule-based self-recovery system
Summary
A facile method is to fabricate responsive materials containing metal ions (such as Ag+, Pb2+) which can be precipitated with chloride ions to participate the wall formation of capsules. When these smart responsive capsules contact with chloride ions, the metal ions will be extracted out to disintegrate the capsules (Fig. 1a). Sodium alginate can be crosslinked with many metal ions (such as Ca2+) to form hydrogel. In this experiment, Ag+ is chosen to be coordinated with alginate to form the wall materials of capsules, silver alginate (Ag-alg) can form a characteristic “egg-box” structure[23]. Each alginate molecular chain can be linked with other chains, causing the formation of a three-dimension gel network (Fig. 1b)[24], which has enough strength to form the wall
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