Tough Supramolecular Polymer Networks with Extreme Stretchability and Fast Room‐Temperature Self‐Healing

TLDR

Recent advances in tough, stretchable polymer networks highlight their promise for wearable electronics and biomaterials, yet achieving the simultaneous demands of stiffness, strength, toughness, damping, fatigue resistance, and self‑healing remains highly challenging. The study aims to build supramolecular polymer networks via in situ copolymerization of acrylamide with functional monomers that are dynamically complexed by cucurbit[8]uril. The networks are formed by in situ copolymerization of acrylamide and functional monomers, with cucurbit[8]uril generating CB[8]-mediated non‑covalent crosslinks. These networks, with high molecular weight and only 2.5 mol % CB[8] crosslinking, are exceptionally stretchable (over 100×), tough, self‑healing at room temperature, ionically conductive, transparent, and can lift 2000× their weight, making them suitable for large‑scale production of wearable and self‑healing electronic devices and structural biomaterials.

Abstract

Recent progress on highly tough and stretchable polymer networks has highlighted the potential of wearable electronic devices and structural biomaterials such as cartilage. For some given applications, a combination of desirable mechanical properties including stiffness, strength, toughness, damping, fatigue resistance, and self-healing ability is required. However, integrating such a rigorous set of requirements imposes substantial complexity and difficulty in the design and fabrication of these polymer networks, and has rarely been realized. Here, we describe the construction of supramolecular polymer networks through an in situ copolymerization of acrylamide and functional monomers, which are dynamically complexed with the host molecule cucurbit[8]uril (CB[8]). High molecular weight, thus sufficient chain entanglement, combined with a small-amount dynamic CB[8]-mediated non-covalent crosslinking (2.5 mol%), yields extremely stretchable and tough supramolecular polymer networks, exhibiting remarkable self-healing capability at room temperature. These supramolecular polymer networks can be stretched more than 100× their original length and are able to lift objects 2000× their weight. The reversible association/dissociation of the host-guest complexes bestows the networks with remarkable energy dissipation capability, but also facile complete self-healing at room temperature. In addition to their outstanding mechanical properties, the networks are ionically conductive and transparent. The CB[8]-based supramolecular networks are synthetically accessible in large scale and exhibit outstanding mechanical properties. They could readily lead to the promising use as wearable and self-healable electronic devices, sensors and structural biomaterials.