Synthesis of UV-Responsive Self-Healing Microcapsules and Their Potential Application in Aerospace Coatings

Abstract

Advanced polymer composite coatings in the spacecraft are threatened by harsh space environment factors, such as strong UV radiation, atomic oxygen, thermal cycles, space debris, etc. Their service life can be drastically shortened by the unavoidable formation of cracks caused by these factors (especially strong and abundant UV radiation) during long-term flight. Herein, a UV-responsive microcapsule-based coating is developed for in-orbit damage repairing. UV-responsive microcapsules of which the inner polymeric shell can be degraded rapidly by the outer pure TiO2 shell under UV radiation are produced by UV-initiated polymerization of Pickering emulsions and subsequently embedded into silicon resin matrices. When damaged, some microcapsules will be ruptured under the stimulus of external force, afterward the unbroken ones around the scratched areas will be degraded by UV radiation, as a result, encapsulated healing agents can be released and finally repair cracks. In this system, UV-responsive microcapsules can release more agents more effectively due to the dual release mode, compared with the traditional crack-repairing system. Moreover, the damage of UV radiation in space can be transferred into the favorable ones, which makes it have a potential application in aerospace coatings.