Eggshell-inspired high-load rigid porous microcapsules for efficient self-healing of multimodal damage in insulating materials

To address the inherent trade-off between mechanical strength and repair efficiency in conventional microcapsule-based self-healing technologies, this study presents an eggshell-inspired approach for fabricating high-load rigid porous microcapsules (HLRPMs) through subcritical water etching. By optimizing the subcritical water treatment parameters (OH⁻ concentration: 0.031 mol/L, temperature: 240 °C, duration: 1.5 h), nanoscale through-holes were generated on hollow glass microspheres (shell thickness ∼ 700 nm). The subsequent gradient pressure infiltration of flaxseed oil enabled a record-high core content of 88.2%. Systematic investigations demonstrated that incorporating 3 wt% HLRPMs into epoxy resin composites preserved excellent dielectric properties (breakdown strength ≥ 30 kV/mm) and enhanced tensile strength by 7.52%. In addressing multimodal damage, the system achieved a 95.5% filling efficiency for mechanical scratches, a 97.0% reduction in frictional damage depth, and a 96.2% recovery of insulation following electrical treeing. This biomimetic microcapsule system concurrently improved self-healing capability and matrix performance, offering a promising strategy for the development of next-generation smart insulating materials.