Co-ordinated polyhedral oligomeric silsesquioxane and cyclodextrin on polyurethane elastomer with network topology for simultaneously improved fatigue-resistant and self-healable properties

Abstract

Long-term usage can induce cracks on the surface or inside the polyurethane (PU) and cause fatigue damage, thus reducing the performance and lifetime of PU. It is therefore of great practical importance to impart fatigue resistance and self-healing ability to PU. However, the conventional covalent cross-linked network design with irreversible and rigid properties limits their fatigue resistance. Here, we have designed a highly ductile, fatigue-resistant and self-healing PU enabled by the synergistic effect of covalent network topology, dynamic reversible disulfide bonds and multiple hydrogen bond stacking. This judicious design yields excellent mechanical properties such as high tensile strength (7.38 MPa), high elongation at break (1159%) and high toughness (42.91 MJ·m−3). Notably, the PU successfully combines fatigue resistance with self-healing behavior. During 1000 cycles of stretch-release processes at 100% strain, the stress retention of the PU almost unchanged. Moreover, the PU achieves a high self-healing efficiency of 98% after self-healing at 80 ℃ for 2 h. The above-mentioned superiority enables the PU-based strain sensors to have a timely and stable output signal as well as excellent self-healing performance. Such a judicious strategy will facilitate the practical application of durable flexible electronics.