A room‐temperature self‐healing anticorrosion coating of supramolecular polyurethane based on dynamic reversible quadruple hydrogen bond

Abstract

AbstractThe contradiction between the migration rate of molecular chains and mechanical strength has always been a key factor affecting the practical application of self‐healing anticorrosion coatings. In this paper, a series of supramolecular self‐healing elastomers (SPU‐MP) were prepared by the reaction of diphenylmethane diisocyanate and polyether amine. The results shown that the proportion of polyetheramine D230 (D230) in molecular segments affects the hydrogen bond density between molecular chains, thereby affecting the self‐healing efficiency and mechanical strength of SPU‐MP. When the ratio of D230 and polyetheramine D400 (D400) is 2:8, the tensile fracture strength of SPU‐MP8 is 5.08 MPa, and the self‐healing efficiency reaches 82.1% after 10 h of repair at room temperature. Further increasing the ratio of D230 increases the relaxation time of the molecular chain due to the increase in hydrogen bond density, resulting in a decrease in the self‐healing efficiency of SPU‐MP. The results of electrochemical experiments and neutral salt spray experiments indicate that the anticorrosion coating prepared by SPU‐MP8 exhibits good self‐healing performance. After immersing in 3.5 wt.% NaCl solution for 35 days, the low‐frequency impedance modulus of the intact coating and the scratch coating were both higher than 107 Ω cm2, still shown good anticorrosion ability.