Rapid and efficient synthesis of isocyanate microcapsules via thiol-ene photopolymerization in Pickering emulsion and its application in self-healing coating

We report an efficient and novel method for encapsulation of isophorone diisocyanate (IPDI) in polythioether microcapsules via thiol-ene click reaction based on Pickering emulsion, which has significantly improved and simplified the preparation process. The resultant microcapsules have spherical shapes with a layer of poly(glycidyl methacrylate) (PGMA) particles covering outside. The diameter ranges from 82.1 to 160.8 μm, which is controlled by the concentration of PGMA particles, and the typical shell thickness is about 9 μm. Moreover, the core content is up to 71% by adjusting the adding ratio of core/shell monomers. Remarkably, the microcapsules have excellently environmental stability that only 18% of the core content drops (from 63.2% to 51.8%) after immersion in water for seven days. These microcapsules could keep their integrity and uniformly disperse in acrylate coatings. In addition, they are proved to be a good self-healing candidate for coatings applied in wet environment.