Robust, high-temperature and solvent tolerant, yet detachable polyimide adhesives enabled by dynamic boroxines

Abstract

Detachable polymeric adhesives (DPAs) usually exhibit weak environmental reliability due to the intrinsic reversible network. Herein, such problem is solved by incorporating dynamic covalent boroxine bonds into high performance engineering polyimide (PI) network as crosslinkers. We demonstrate the boroxine crosslinked PI DPAs (denoted as PI-B3O3 DPAs) with simultaneously robust tensile strength (111.3 MPa), high interfacial bonding strength (26.0 MPa), and extremely environmental reliability including high-temperature tolerance (5% weight loss of ∼541.6 °C, adhesion strength after pretreating of 25.8 MPa at 300 °C, 22.6 MPa at 350 °C, and 18.3 MPa at 400 °C) and solvent stability (10 different solvents including acids, bases and organic solvents). Moreover, the PI-B3O3 DPAs can be further detached and recycled with the help of specific mixture solvent. The high tensile strength and extremely environmental tolerance are enabled by the rigid PI main chain and high bond energy of boroxines. Besides, the boroxine crosslinkers in PI-B3O3 network can help to balance its cohesion energy and interfacial adhesion energy, which guarantees its robust initial bonding strength in DPAs. At Last, due to the high reversibility of boroxines, the PI-B3O3 DPAs can be conveniently detached and recycled in the presence of specific mixture solvent.