Self dicyclopentadiene

During the last years ROMP has been developed to generate self-healing polymers. In these polymers droplets of dicyclopentadiene and of Grubbs-catalyst are incorporated. When the polymer cracks the droplets burst open, the catalyst comes into contact with the monomer and the plastic ideally heals itself [111]. This methodology is still far from application but it does indicate the power of ROMP. 

The self-healing system is based on microcapsules containing liquid dicyclopentadiene... 

Using NRs, White and coworkers developed self-repaired polymers. This approach was based on incorporation of microcapsules loaded with healing agents, dicyclopentadiene monomers, and using a proper catalyst in epoxy matrix. Formation of cracks ruptured the microcapsules and released healing... 

Conjugated cyclic dienes, in which the double bonds are of necessity held in an s-cis conformation, are highly reactive in Diels-Alder reactions. Two particularly useful dienes for this purpose are cyclopentadiene and 1,3-cyclohexadiene. In fact, cyclo-pentadiene is reactive both as a diene and as a dienophile, and upon standing at room temperature, it forms a Diels-Alder self-adduct known by the common name dicyclopentadiene. When dicyclopentadiene is heated to 170°C, a reverse Diels-Alder reaction takes place and cyclopentadiene is reformed. 

The present work covers a variety of self-healing motifs, systems, and chemistries. The first example of a practical fully self-contained self-healing system based on microencapsulated dicyclopentadiene and Grubbs catalyst particles embedded in an epoxy matrix,) 16) formed the basis for further research on similar self-healing systems and thus forms the basis for the discussion presented herein. For all chemistries discussed, the efforts in compartmentalization of the reactants, evaluation of self-healing performance, and testing in relevant applications such as reinforced polymer composites and coatings are presented. 

Fig. 1. Original microencapsulation-based self-healing system. Microencapsulated dicy-clopentadiene is embedded in an epoxy resin containing Grubbs catalyst which is capable of polymerizing the dicyclopentadiene. A propagating crack ruptures the microcapsules causing DCPD to be released into the crack plane where it comes in contact with and reacts with catalyst to form a polymer that bonds the crack hices and restores structural continuity.

---