Preparation of pH-sensitive core-shell organic corrosion inhibitor and its release behavior in simulated concrete pore solutions

Publication date: 5 April 2017
Source:Materials & Design, Volume 119
Author(s): Yangyang Zhu, Yuwei Ma, Qijun Yu, Jiangxiong Wei, Jie Hu
In this paper, core-shell organic corrosion inhibitors (COCI) based on poly(ethylene oxide)-b-polystyrene (PEO-b-PS) copolymers were successfully prepared. The release process of benzotriazole (BTA) reserved in COCI was investigated by UV spectrophotometry in deionized water and simulated concrete pore (SCP) solutions with different pH values, and the size and morphology of COCI were determined by dynamic light scattering measurements and SEM combined with EDS before and after the release process. The release amount of BTA was slightly higher (9%) in deionized water with lower pH values, which was related to the higher protonation degree of oxygen groups in PEO moieties and less compact structure of COCI at lower pH environment. In SCP solutions, the pH sensitivity of BTA release process was more pronounced, evidenced by 5 times lower release amount of BTA in SCP solution with a pH value of 13, compared to SCP solutions with pH values lower than 11. The most plausible reason is that in SCP solution with a pH value of 13, the existence of Ca²⁺ and high alkaline environment are beneficial for the agglomeration of COCI and formation of Na-rich layer around COCI, hindering the diffusion rate and subsequently release process of the reserved BTA.

Graphical abstract

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