Robust Dynamic Epoxy Adhesives with High Environmental Tolerance Enabled by the Coordination of Small-Molecule Coupling Agents with Boroxine

Abstract

Developing dynamic epoxy adhesives (DEAs) with simultaneously strong adhesion, extreme environmental tolerance, and on-demand detachability is in high demand in the future but remains challenging. In this work, we prepared a robust and dynamic epoxy adhesive cross-linked with boroxines, and a small-molecule coupling agent was introduced to coordinate with boroxines to improve its environmental reliability. Owing to the high exchangeability of boroxines and the coordination of amino group with boroxines, the as-developed adhesive shows simultaneously good mechanical properties (tensile strength of 53.55 MPa, fracture toughness of ∼27.3 MJ m–3), excellent lap shear strength (20.5 MPa), good resistance to water (18.8 MPa after soaking in water for 30 days), pH, and high and low temperatures (20.1 MPa at 100 °C, 27.8 MPa at −196 °C), and can be quickly removed and recycled by soaking in specified solvents.

Ultralow-Temperature-Tolerance Adhesive with Excellent Toughness and Record-High Strength

“…Therefore, the debonding energy increases from 5.34 ± 3.21 kN/m (HTA 0 ) to 61.16 ± 10.69 kN/m (HTA 0.5 ), 46.47 ± 7.22 kN/m (HTA 1 ), and 61.91 ± 20.12 kN/m (HTA 2 ), respectively, with an increase of 1045%, 770% and 1059%, respectively (Figure c). To the best of the authors’ knowledge, the lap-shear strength and the debonding work are 5 times higher than those reported in literatures ,− (Figure d), which is due to the relatively lower cross-sectional point of HTA 0.5 in the rheological modulus plot compared to HTA 1 . Taking HTA 0.5 as an example, it was further investigated at various temperatures and bonded to different substrates.…”