Reversible and Ultrastrong Epoxy‐Polyurethane Adhesives with Microphase Separation

Abstract Reversible adhesives permit adaptability and sustainability in advanced materials and devices. However, their implementation is significantly hampered by poor adhesive strength owing to the critical trade‐off between interfacial adhesion and cohesion energy preservation, as well as the challenge of large‐scale and low‐cost manufacturing. Herein, a class of ultrastrong reversible adhesives integrating epoxy (EP) and polyurethane (PU) via dynamic furan‐maleimide chemistry is reported, which features well‐tunable microphase‐separated structures. The interspersed rigid EP domains provide remarkable cohesive strength, while the continuous flexible PU phase dissipates mechanical energy through chain extension and hydrogen‐bond dissociation, enhancing both toughness and adhesion. This unique design allows precise tuning of mechanical and adhesive properties across a large range, maintaining thermo‐reversibility while enabling scalable manufacturing. Notably, the EP‐PU adhesive achieves an ultrahigh adhesion strength (34.6 MPa), substantially outperforming most reversible adhesives reported so far, while matching commercial structural adhesive standards. Meanwhile, the adhesive displays exceptional multiple reusability, on‐demand separation capacity, broad substrate compatibility, and satisfactory environmental stability.