Harnessing\nImine Chemistry for the Debonding-on-Demand\nof Polyurethane Adhesives

Traditional adhesives\noften result in irreversible bonds, hindering\ndisassembly and recycling processes. In response to the growing demand\nfor sustainable practices, researchers have explored alternative bonding\nsolutions. Debonding-on-demand adhesives represent a breakthrough,\nenabling selective weakening or breaking of adhesive bonds when desired\nand facilitating efficient disassembly, repair, and recycling of bonded\nmaterials. This has profound implications across industries, including\npackaging, footwear, automotive, and electronics, where the recycling\nof bonded components plays a crucial role in resource conservation.\nHerein, we present the incorporation of an imine-based polyol derived\nfrom vanillin and polyetheramine into a model, one-component, polyether-based\npolyurethane adhesives. Such systems retained their thermal performance,\nexhibiting onset degradation temperatures of ∼320 °C and\nglass transition temperatures of ∼−50 °C, similar\nto the reference adhesive. Additionally, they demonstrated adhesive\nperformance comparable to that of the reference system, with lap-shear\nstrengths ranging from 1.7 to 2.1 MPa. In addition to that, imine\npolyol incorporated adhesives offered enhanced recyclability through\non-demand debonding of the bonded substrates to obtain adhesive-free\nsurfaces by acidic hydrolysis of the imine functional groups. These\nfindings undoubtedly contribute to the advancement of sustainable\nmaterial practices and promote a circular economy, emphasizing the\nimportance of adhesive technology in addressing environmental challenges.