Achieving High-Strength Polymer Adhesion Through Bond Exchange at the Interphase

Bond-exchangeable cross-linked materials, including covalent adaptable networks and vitrimers, exhibit numerous advantageous properties such as reprocessability, recyclability, and healability. These features arise from the relaxation and diffusion of network polymers facilitated by bond exchange within the network. The application of these materials in functional adhesives is particularly promising, given the growing demand across various industries. It is well established that vitrimer films can adhere to a wide range of substrates. In this study, a novel concept of bond exchange-based adhesion between different polymers is introduced, specifically noting that each polymer does not inherently possess bond-exchange capabilities. The key feature lies in activating bond exchange exclusively at the interphase. Significant adhesion between commercial thermoplastic polyurethanes and cross-linked poly(acrylate)s with hydroxy side groups randomly is demonstrated, achieved through transcarbomoylation bond exchange at the contact interphase. The incorporation of a small amount of bond exchange catalyst is crucial for enhancing adhesion, and both adhesion strength and fracture behavior can be manipulated through specific heating conditions. Overall, this study explores a new functionalization approach using the bond exchange concept, contributing to the development of a practical adhesion technique that eliminates the need for traditional adhesives.