Dynamic Disulfide Bond-Driven the Shape-Adaptive Self-Healing of Polyurethane Microcapsules

The limited self-healing capability of materials synthesized using conventional isocyanate-based microcapsules as repair agents highlights the need for innovative microcapsule systems. In this study, a novel microcapsule (PU1) design is introduced that incorporates dynamic disulfide bonds, endowing the microcapsule walls with self-healing properties. Additionally, a comparative analysis is performed with conventional microcapsules (PU2) synthesized using 1, 4-butanediol. The prepared PU1 microcapsules exhibited a typical shell-core structure, and the median particle size decreased with increasing stirring speed. The glass transition temperature (T_g) of the prepared PU1 microcapsule is -53.2 °C, while that of the PU2 microcapsules is -45.0 °C. Moreover, after being placed at 60 °C for 24 h, the damaged PU1 microcapsules effectively self-healed. In contrast, the PU2 microcapsules do not demonstrate significant self-healing properties. Furthermore, elastomer films with the same chemical composition are prepared, and the tensile strength and the elongation at break of the PU1 elastomer are 7.3 MPa and 1450%, respectively, demonstrating excellent mechanical properties. This work provides a novel approach for preparing intrinsic self-healing polyurethane microcapsules, which is expected to solve the issue of non-repetitive healing in external self-healing materials.