Preparation and application of self-healing elastomers and coatings at ambient temperature based on semi-interpenetrating polymer networks

Self-healing coatings materials have a wide application in various fields, but achieving a high self-healing property and efficiency at ambient temperature without any additional power is still a big challenge. In this work, a series of elastomers (named LPU-1/EP) were successfully prepared based on a concept of semi-interpenetrating polymer networks. Linear polyurethane (LPU) is used as the "dynamic flow" component, while, epoxy networks provide the necessary mechanical strength. The formation of semi-interpenetrating polymer networks and dynamic hydrogen bonds are conducive to balance self-healing performance and high mechanical strength of the prepared elastomers from the results of rheological test and surface analysis. The typical sample, i.e., LUP-1/EP-3 elastomer, had the highest tensile strength of 1.43 MPa and outstanding ambient temperature self-healing efficiency. The mechanical strength of self-healing LUP-1/EP-3 elastomer was good, and the biggest loading could be more than 1500 mL water after 5 min of self-healing. The toughness of the broken LUP-1/EP-3 elastomer had a recovery value of 81.8% compared to the intact specimen. Furthermore, the LUP-1/EP self-healing coatings were prepared, and the scratch line of LUP-1/EP-3 coatings turned out to be blurry and eliminated after 96 h of self-healing at 30 °C. Electrochemical measurements indicated that both the intact and self-healing LUP-1/EP-3 coatings had a high corrosion protection effect after 75 d of testing in 3.5 wt.% NaCl solution and their impedance values had the same change tendency. LPU-1/EP-3 conductive coating also had a good self-healing performance from the tests of conductive property.