An impact-strengthening, reusable hot-melt structural adhesive derived from branching polyurethane-based supramolecular topology capped by self-complementary hydrogen bonding UPy motifs

The miniaturization and reliability of portable electronics are increasingly dependent on structural adhesive while developing detachable, reusable, and recyclable adhesives remain great challenge. Herein, we developed a novel strategy of incorporating self-complementary quadruple hydrogen bonds into multi-branch polyurethane as terminal motifs to construct supramolecular adhesive. Impressively, the as-synthesized TPU-UPy was endowed with a high adhesion strength of 6.8 MPa for steel and featured excellent multiple reusability with more than 70% of the original adhesion strength remained even after reuse for five times. More importantly, it exhibited increasing trend of adhesive strength as the stretching speed increases, suitable for application of anti-impact. The way of generating UPy motifs by this synthetic route did not involve excessive consumption of reactants, which was potential to be industrialized. Thus, the TPU-UPy is a candidate hot melt adhesive that can be put into practical use of portable electronics encountering occasional impact.