The Polymer Society of Korea

Abstract

 As the form factors of next-generation information technology evolve, there is a growing demand for high-performance coating materials that ensure the durability of wearable devices without compromising their lightweight nature. Self-healable colorless polyimide (CPI) is a promising candidate to replace rigid external glass due to its high optical transparency, chemical resistance, and design freedom. However, realizing practical self-healing typically requires low-temperature activation, which often necessitates lowering the glass transition temperature (Tg) at the cost of mechanical hardness and strength. To circumvent this inherent trade-off, we propose a facile blending strategy incorporating 5 wt% polyurethane (PU) into a CPI matrix. This approach resulted in a synergistic enhancement of tensile strength, flexibility, and heat resistance, while simultaneously lowering the healing temperature required for repairing surface damage. These improved characteristics are attributed to the specific intermolecular interactions between the PI and PU chains. Consequently, we demonstrate that this self-healable colorless PI-PU blend serves as an ideal transparent protective coating for flexible displays and wearable electronics, providing a practical solution for maintaining surface integrity and long-term reliability.