Fabrication of high-quality microcapsules containing ionic liquid for application in self-healing conductive materials

Conductive materials inevitably develop micro-cracks during processing or use, which seriously impairs the performance and lifetime of their associated devices. Autonomous recovery of conductivity can greatly improve in-service reliability and extend service life. Herein, microcapsules containing conductive ionic liquid (IL) were successfully synthesized using a novel microencapsulation technique via integrating electrostatic spraying and interfacial polymerization (ES-IP), and their high potential for conductivity restoration of conductive pastes for printed circuits was verified. The prepared ionic liquid microcapsules (IL-MCs) have good dispersibility, great solidity, and tunable properties. Self-healing conductive composites were prepared by incorporating the synthesized microcapsules into the conductive slurry and the effect of microcapsule content in the matrix on the restoration was investigated. The conductivity recovery tests show that IL-MCs recover the conductivity of the damaged samples with an efficiency of about 96%. While the restoration efficiency remains essentially stable with increasing the microcapsule content, the chance of restoration increases. When the microcapsule content was 20%, the probability of the damaged samples being autonomously repaired is about 84%. It proves that the successful microencapsulation of IL using the ES-IP technique broadens the applications of ILs in conductive materials.