Stimuli‐responsive polymeric additives for anticorrosion

Abstract

Corrosion is a significant issue for metals and alloys items because it critically affects their lifetimes. To protect the metal from corrosion, corrosion inhibitors can be added into coatings, but the inhibitor can leach into the environment. Polymer‐corrosion inhibitor conjugates are developed to solve this problem. However, corrosion can occur in various fields of applications, which then need a different level and type of metal's protection. β‐thiopropionate and ester linkages between polymer and inhibitor are selected as model for very labile and moderately labile linkages, respectively. The rate of inhibitor's release is controlled by the linkage of conjugated payloads. Corrosion measurements indicated that polymers with the β‐thiopropionate linkage are suitable for severe corrosion and short‐term applications, whereas the polymers with ester linkage can be used for mild corrosion and long‐term applications.

Corrosion‐Responsive Self‐Healing Coatings

“…It can be noted that the linkages in polymer can be designed to allow both a fast and slow release of the same or different inhibitors from the same polymer chain. [151,152] Disulfide bonds are redox-cleavable linkages that can be incorporated in active polymers for anticorrosion. The corrosion inhibitor MBT was conjugated to polymer backbones via disulfide linkages prepared through a thiol-disulfide exchange reaction.…”

“…In fact, they are mainly limited to so called accelerated tests, such as salt spray tests. Salt spray testing, which consists in submitting coated metallic substrates to saline vapor at controlled temperature, was used to assess the long-term durability of extrinsic [88,89,99,108,111,114,119] and intrinsic [53,148,152] self-healing coatings. It is claimed that 120 h of salt spray test may be comparable to 5 years of exposure to a C3 corrosive atmosphere.…”

“…It is claimed that 120 h of salt spray test may be comparable to 5 years of exposure to a C3 corrosive atmosphere. [152] However, the relevance of salt spray tests is highly disputed, as results are often observed to significantly deviate from those obtained in long-term field exposure tests. [4] Radhakrishnan et al reported epoxy coatings containing up to 7 wt% PANI particles with a quite high long-term stability of at least 1500 h in 3.5 wt% NaCl solution (65 and 75 °C) and 700 h salt spray test.…”

“…It can be noted that the linkages in polymer can be designed to allow both a fast and slow release of the same or different inhibitors from the same polymer chain. [ 151,152 ]…”

“…It is claimed that 120 h of salt spray test may be comparable to 5 years of exposure to a C3 corrosive atmosphere. [ 152 ] However, the relevance of salt spray tests is highly disputed, as results are often observed to significantly deviate from those obtained in long‐term field exposure tests. [ 4 ]…”