Electrically Detachable Ionic Conductive Epoxy Adhesives with High Bonding Strength

Abstract

Detachable adhesives are considered to be an essential strategy to realize reuse and recycle of the bonded components, but it is a great challenge to fabricate a detachable adhesive with ultra-high bonding strength. In this study, electrically detachable ionic conductive epoxy adhesives (IEPs) are prepared through introduction of poly­(ethylene glycol) (PEG) and 1-butyl-3-methylimidazolium bis­(trifluoromethylsulfonyl)­imide ([BMIM]­TFSI) into epoxy. It is found that an initial bonding strength of more than 20 MPa can be realized via adjusting the PEG molecular weight due to the stronger crystallization tendency of PEG with a higher molecular weight that shows remarkable reinforcement and strengthening effect. In spite of the ultra-strong bonding of the IEPs, they can be completely and automatically detached by applying 60 V DC voltage within 1 min. The electrically detaching mechanisms of IEPs are further studied and it is confirmed that the electrically detaching behavior is dependent on the electrodecomposition of ionic liquids; thus, the electrodecomposition mechanism of [BMIM]­TFSI and the impacts on bonding substrates are presented. It is believed that this work provides an effective strategy for developing electrically detachable adhesives with ultra-high initial bonding strength.