Damage-resistant and healable polyacrylonitrile-derived stretchable materials with exceptional fracture toughness and fatigue threshold

PAN-based stretchable materials with high fracture toughness and fatigue threshold. Stretchable materials are widely used in various aspects of our daily lives, however, achieving excellent short and long-term damage tolerance in them, i.e. , high fracture toughness and fatigue threshold at the same time, remains a challenge. Herein, we report a healable and stretchable material with exceptional damage tolerance based on Al 3+ coordinated partiallyamidoximated polyacrylonitrile (Al 3+ -APAN). Due to the presence of strong coordination bonds and polymer crystalline aggregates, the obtained material exhibits a high fracture toughness of 102.29 ± 5.94 kJ m −2 and a high fatigue threshold of 1.73 ± 0.045 kJ m −2 , exceeding those of many natural and synthetic materials. Besides, Al 3+ -APAN possesses a good tensile strength of up to ∼14 MPa, a high elastic modulus of up to ∼47 MPa, and can be conveniently healed if damaged, thus greatly extending its service time. We believe that this work provides a straightforward strategy to develop tough, healable and stretchable materials with exceptional damage-tolerance for advanced applications such as in protective coatings, wearable electronic devices and soft robotics.