Low-Temperature Self-Healing of a Microcapsule-Type Protective Coating

Abstract

Abstract:Low-temperature self-healing capabilities are essential for self-healing materials exposed to cold environments. Although low-temperature self-healing concepts have been proposed, there has been no report of a microcapsule-type low-temperature self-healing system wherein the healing ability was demonstrated at low temperature. In this work, low-temperature self-healing of a microcapsule-type protective coating was demonstrated. This system employed silanol-terminated polydimethylsiloxane (STP) as a healing agent and dibutyltin dilaurate (DD) as a catalyst. STP underwent a condensation reaction at −20 • C in the presence of DD to give a viscoelastic product. The reaction behavior of STP and the viscoelasticity of the reaction product were investigated. STP and DD were separately microencapsulated by in situ polymerization and interfacial polymerization methods, respectively. The STP-and DD-loaded microcapsules were mixed into a commercial enamel paint, and the resulting formulation was applied to glass slides, steel panels, and mortars to prepare self-healing coatings. When the self-healing coatings were damaged at a low temperature (−20 • C), STP and DD were released from broken microcapsules and filled the damaged area. This process was effectively visualized using a fluorescent dye. The self-healing coatings were scratched and subjected to corrosion tests, electrochemical tests, and saline solution permeability tests. The temperature of the self-healing coatings was maintained at −20 • C before and after scratching and during the tests. We successfully demonstrated that the STP/DD-based coating system has good low-temperature self-healing capability.

Self‐healing and reprocess of crosslinked polyurethane based on dynamic oxime‐carbamate bond

“…4 Although these extrinsic self-healing materials have reliable healing processes, the healing times of the materials are limited due to the exhaustion of the healing agent. [5][6][7] Intrinsic self-healing materials based on dynamic bonds including noncovalent dynamic linkages (such as host-guest interactions, π-π stacking interactions, hydrogen bonds and so on) and covalent dynamic reversible bonds (such as disulfide bonds, Diels-Alder reaction, oxime-carbamate bonds and so on) can theoretically heal unlimited times, [8][9][10][11][12][13] and have become the major direction of self-healing materials. Among them, oxime-carbamate( NHCOO N C ) is prepared by the reaction of isocyanates and oximes, 14,15 the strong electron-withdrawing of the imine bond ( C N ) makes the oxime-carbamate bond unstable, the oximecarbamate groups can dissociate into oxime and isocyanate groups at elevated temperature, again to reform the oxime-carbamate group.…”

Effect of mechanical properties on the self‐healing behavior of waterborne polyurethane coatings

“…Reversible chemistry attracted more research efforts due to its reversible nature, and a variety of reversible reactions could be utilized to introduce self‐healing ability to polymer materials. Especially, the dynamic exchange of disulfide bonds is known to transfer readily without the need for any stimulation like catalyst or light, thus providing a mechanism for self‐healing under mild conditions 10–15 . Combining disulfide bonds and the great versatility of polyurethane, disulfide bonds were incorporated into WPU networks by reacting 2‐hydroxyethyl disulfide (HEDS) along with aliphatic prepolymer chains synthesized from isophorone diisocyanate (IPDI) and poly(tetramethylene ether glycol) (PTMG).…”

Shape-Memory and Self-Healing Polymers Based on Dynamic Covalent Bonds and Dynamic Noncovalent Interactions: Synthesis, Mechanism, and Application

“…In nature, living organisms can repair damaged tissues and functions. Inspired by this ability, researchers have successfully manufactured various self-healing materials to extend the service life of the materials, such as concrete, , metals, , and polymer materials. , Among them, self-healing polymers have been widely used in various fields such as biomedicine, − tissue engineering, and protective coatings. − …”