Healable and Debondable Poly(furfuryl methacrylate) Thin Film Adhesive Based on Diels-Alder Networks

The increasing demand for adhesives in industry comes with environmental concerns, particularly regarding sustainability and waste reduction. Developing reusable or reversible adhesives can extend their service life and reduce plastic waste. Herein, thin poly(furfuryl methacrylate) (pFMA) film with thicknesses around 500 nm was prepared via initiated chemical vapor deposition (iCVD) on different substrates. Then, two pFMA-coated substrates were bonded with aliphatic bismaleimide to obtain a reversible adhesive through the Diels-Alder (DA) reaction. The thin film DA adhesive showed cohesive failure result, validating effective cross-linking on both sides and strong affinity between the film and substrate. No adhesion occurred when furan groups were replaced by epoxy groups. The DA adhesive presented robust adhesion performance, with a lap shear strength of 3.07 MPa and maintained reversibility over three adhesion-debonding cycles, unlike commercial cyanoacrylate glues, which typically adhere only once. It is crucial to maintain a small initiator/monomer ratio during iCVD to avoid excess allylic furan radicals and guarantee the retention of furan groups for strong adhesion. Additionally, the reversible adhesive displayed stable and excellent resistance against creep deformation, operating without failure from 25 to 200 °C. The iCVD technique also allows for easy coating of pFMA films on porous surfaces, enhancing the potential for industrial applications of healable DA adhesive.