High-strength, stretchable, and NIR-induced rapid self-healing polyurethane nanocomposites with bio-inspired hybrid cross-linked network

Stretchable and self-healable materials with excellent mechanical performance hold great promise for applications in flexible functional devices. Despite rapid developments, achieving high mechanical strength, extreme stretchability, and rapid self-healing capability in self-healing materials remains challenging. Here, inspired by the hierarchical structure and unique network of connective tissue, we fabricated a class of bionic nanocomposites with high stretchability, outstanding mechanical strength, and rapid self-healing ability by integrating the bottlebrush copolymer functionalized graphene oxide (BCP@GO) into a polyurethane (PU) matrix via in-situ polymerization. The bottlebrush copolymer (BCP) acted as a bond bridge for linking the GO nanosheets (noncovalent interaction) and PU chains (covalent and hydrogen-bond interaction). The covalent interactions were responsible for providing high mechanical strength, and the abundant hydrogen-bond-based cross-links realized extreme stretchability and rapid self-healing capability. The resultant BCP@GO/PU nanocomposite with only 0.5 wt.% GO loading exhibited excellent mechanical properties (tensile strength increased by 52.1%, up to 28.6 MPa; toughness increased by 70.8%, up to 256.9 MJ/m³; elongation at break increased by 12.8%, up to 1847.2%), exceptional rapid and efficient self-healing ability (~ 99% with 20 s NIR irradiation), as well as superior shape memory and recyclable capability. This study develops a new strategy for designing high-performance self-healing nanocomposites and unfolds broad application prospects in smart materials.