A self-joining polymer composition, comprising a polymer, a plurality of amine pendant groups attached to the polymer and a plurality of microcapsules of flowable polymerizable material dispersed in the polymer where the microcapsules of flowable polymerizable material including microcapsules and flowable polymerizable material inside the microcapsules. The microcapsules are effective for rupturing with a failure of the polymer so the flowable polymerizable material cross-links with the reactable pendant groups upon rupture of the microcapsules.