Mechanically Interlocked [an]Daisy Chain Adhesives with Simultaneously Enhanced Interfacial Adhesion and Cohesion.

Adhesives have been widely used to splice and repair materials to meet practical needs of humanity for thousands of years. However, developing robust adhesives with balanced adhesive and cohesive properties still remains a challenging task. Herein, we report the design and preparation of a robust mechanically interlocked [an]daisy chain network (MIN) adhesive by orthogonal integration of mechanical bonds and 2-ureido-4[1H]-pyrimidone (UPy) H-bonding in a single system. Specifically, the UPy moiety plays a dual role: it allows the formation of a cross-linked network and engages in multivalent interactions with the substrate for strong interfacial bonding. The mechanically interlocked [an]daisy chain, serving as the polymeric backbone of the adhesive, is able to effectively alleviate applied stress and uphold network integrity through synergistic intramolecular motions, and thus significantly improves the cohesive performance. Comparative analysis with the control made of the same quadruple H-bonding network but with non-interlocked [an]daisy chain backbones demonstrates that our MIN possesses superior adhesion properties over a wide temperature range. These findings not only contribute to a deep understanding of the structure-property relationship between microscopic mechanical bond motions and macroscopic adhesive properties but also provide a valuable guide for optimizing design principles of robust adhesives.