Direct microencapsulation of Ionic-Liquid-Based shear thickening fluid via rheological behavior transition for functional applications

In nature, various stimuli-responsive materials, such as bone, are self-adaptable to external loading by modulating their mechanical properties to prevent failure and self-healing after damage. Herein, for the first time, an oil-in-oil solvent-evaporation approach is proposed to directly microencapsulate a multifunctional self-adaptive material-ionic-liquid-based shear thickening fluid (ILSTF)-via rheological behavior transition. As the cosolvent completely changed the rheological responses of the dispersed phase, this approach proved ideal for encapsulating STFs with high viscosity and shear-thickening behavior. The resultant ILSTF microcapsules (MCs) exhibited high thermal stability (initial decomposition temperature of similar to 380 degrees C) and controllable size at the micrometer level from 66 to 260 mu m. The typical ILSTF MCs were incorporated into an elastomer matrix, achieving 33 % and 67 % enhancement of energy absorption ability compared with the pure polymer and IL MCs-embedded composites, respectively. Furthermore, the circuit comprised of ILSTF MCs-incorporated flexible conductor exhibited not only electrical stability upon impact, but also autonomic conductivity restoration after injury, demonstrating that the ILSTF MCs can serve as a multifunctional agent for emerging applications, such as deformable circuits and battery safety.

Automated summary

In this study, a solvent-evaporation approach was used to microencapsulate a multifunctional self-adaptive material, called ionic liquid-based shear thickening fluid (ILSTF). The resulting microcapsules exhibited high thermal stability and controllable size, and were incorporated into an elastomer matrix to enhance energy absorption ability. The ILSTF microcapsules also showed potential for applications in deformable circuits and battery safety.