A Fluorescent, Ultrastrong, Silicon-Containing Polyamide Hot-Melt Adhesive with a Nanocrystalline Structure Similar to Spider Silk

Spider silk is recognized as one of the strongest naturally occurring materials due to its unique biphasic structure. Taking inspiration from natural spider silk, an ultrastrong, low-temperature-resistant, reusable thermoplastic silicon-containing polyamide (Si-PA) hot-melt adhesive (HMA) has been synthesized for the first time by melt polycondensation. The obtained Si-PA adhesive possesses a reliable bond strength of up to 20.6 MPa at ambient temperature and 9.5 MPa at −196 °C on stainless steel, notably outperforming comparable polyamide HMAs. These extraordinary performances mainly originate from the meticulously engineered microphase separation structure, wherein nanoscale crystalline regions (20–200 nm) disperse throughout the amorphous regions formed by organosilicon chain segments. Moreover, high-density hydrogen-bond-induced emission of the amide cluster leads to strong blue fluorescence. The Si-PAs show potential in the fields of cold-resistant adhesive devices and tamper-resistant displays. Furthermore, this design provides an idea for mimicking spider silk materials.