Single-Component High-Performance Adhesives Enabled by Synergistic Supramolecular and Covalent Polymerization.

The development of high-strength supramolecular adhesives from a single small molecule is a highly compelling research goal, as it offers the potential for lightweight, reversible, and stimuli-responsive bonding systems. However, achieving such adhesives presents significant challenges. Herein, we present a novel tripodal multifunctional molecule, , designed to exploit a synergistic supramolecular and covalent polymerization strategy to achieve a remarkable adhesive performance. features a central benzene-1,3,5-tricarboxamide (BTA) core from which cyanostilbene moieties extend, each terminating in a benzo-crown-ether macrocycle. Under ambient conditions, while the highly directional hydrogen bonding between tripodal amide groups induces one-dimensional (1D) stacked arrays, the terminal benzo-crown-ether macrocycles facilitate the assemblies of the 1D chains, thereby promoting the formation of supramolecular networks exhibiting a baseline adhesion of 2.28 MPa as measured by lap-shear tests. Notably, under ultraviolet (UV) irradiation, the supramolecular networks undergo additional covalent photo-cross-linking through a [2 + 2] cycloaddition reaction, facilitated by the supramolecular confinement of cyanostilbene moieties. This process significantly enhances the adhesion strength to 5.18 MPa. Comparative studies with model compounds (devoid of crown ether moieties, replaced by acyclic glycol chains) and (with amide units replaced by ester groups) reveal that amide and crown ether units are indispensable for both supramolecular networks and covalent cross-linking.