Multiple H-Bonding Chain Extender-Based Ultrastiff Thermoplastic Polyurethanes with Autonomous Self-Healability, Solvent-Free Adhesiveness, and AIE Fluorescence

Developing an autonomous room temperature self-healing supramolecular polyurethane (PU) with toughness and stiffness remains a great challenge. Herein, a novel concept that utilizes a T-shaped chain extender with double amide hydrogen bonds in a side chain to extend PU prepolymers to construct highly stiff and tough supramolecular PU with integrated functions is reported. Mobile side-chain H-bonds afford a large flexibility to modulate the stiffness of the PUs ranging from highly stiff and tough elastomer (105.87 MPa Young's modulus, 27 kJ m(-2)tearing energy), to solvent-free hot-melt adhesive, and coating. The dynamic side-chain multiple H-bonds afford an autonomous self-healability at room temperature (25 degrees C). Due to the rapid reconstruction of hydrogen bonds, this PU adhesive demonstrates a high adhesion strength, fast curing, reusability, long-term adhesion, and excellent low-temperature resistance. Intriguingly, the PU emits intrinsic blue fluorescence presumably owing to the aggregation-induced emission of tertiary amine domains induced by side-chain H-bonds. The PU is explored as a counterfeit ink coated on the predesigned pattern, which is visible-light invisible and UV-light visible. This work represents a universal and facile approach to fabricate supertough supramolecular PU with tailorable functions by chain extension of PU prepolymers with multiple H-bonding chain extenders.

Automated summary

This study reports the development of a self-healing supramolecular polyurethane with high stiffness and toughness, suitable for applications such as adhesives and coatings. By introducing a T-shaped chain extender with double amide hydrogen bonds in the side chain, the stiffness of the polyurethane can be modulated, allowing for autonomous self-healing capabilities.