High-strength and ultra-tough supramolecular polyamide spider silk fibers assembled via specific covalent and reversible hydrogen bonds

Achieving ultra-high tensile strength and exceptional toughness is a longstanding goal for structural materials. However, previous attempts using covalent and non-covalent bonds have failed, leading to the belief that these two properties are mutually exclusive. Consequently, commercial fibers have been forced to compromise between tensile strength and toughness, as seen in the differences between nylon and Kevlar. To address this challenge, we drew inspiration from the disparate tensile strength and toughness of nylon and Kevlar, both of which are polyamide fibers, and developed an innovative approach that combines specific intermolecular disulfide bonds and reversible hydrogen bonds to create ultra-strong and ultra-tough polyamide spider silk fibers. Our resulting Supramolecular polyamide spider silk, which has a maximum molecular weight of 1084 kDa, exhibits high tensile strength (1180 MPa) and extraordinary toughness (433 MJ/m3), surpassing Kevlar's toughness 8-fold. This breakthrough presents a new opportunity for the sustainable development of spider silk as an environmentally friendly alternative to synthetic commercial fibers, as spider silk is composed of amino acids. Future research could explore the use of these techniques and fundamental knowledge to develop other super materials in various mechanical fields, with the potential to improve people's lives in many ways.