Self-healing polymer encapsulants operate through two primary strategies: extrinsic and intrinsic healing. Extrinsic systems rely on microcapsules or vascular networks embedded within the polymer matrix.
When damage occurs, these containers rupture, releasing reactive agents like monomers or catalysts that polymerize to seal cracks. For instance, epoxy-based encapsulants use dicyclopentadiene (DCPD) microcapsules, which react with catalysts to form robust repairs within minutes.
Intrinsic systems, however, leverage reversible dynamic bonds such as hydrogen bonds, disulfide linkages, or boroxine networks.
These bonds break under stress but spontaneously re-form, enabling repeated healing cycles. A notable example is polyurethane encapsulants with imine bonds, which restore conductivity in drone batteries even after repeated mechanical fractures. Such versatility makes intrinsic polymers ideal for applications requiring multiple repair cycles.