The University of Osaka develops UV-activated adhesive for easy removal

A research group including Professor Yoshinori Takashima at the Graduate School of Science, the University of Osaka, Associate Professor Yoshihisa Fujii at Mie University, Professor Go Matsuba at Yamagata University, and Professor Yasutomo Uetsuji at Osaka Institute of Technology developed an adhesive material that changes the mechanical properties near the adhesive interface upon ultraviolet light irradiation and can be selectively peeled off. It is expected not only to support the recycling and reuse of electronic materials and plastic products but also to serve as a new guideline for the design of next-generation adhesive materials based on dynamic polymer interfaces. The results were published in Matter & Light.

Although adhesives are indispensable in assembling products, once used for bonding, they are difficult to peel off, and substrates or the adhesive itself may be damaged if they are forcibly removed. Therefore, adhesives capable of being peeled off only when necessary after use are demanded. However, conventional stimulus-responsive adhesive materials reduce the mechanical strength of the entire material in response to stimuli, resulting in the problem that adhesive residues remain on the substrate.

The research group focused on photo-responsive elastomers possessing reversible cross-links that they had developed, applying the characteristic that the elastic modulus of the light-irradiated surface changes reversibly to adhesive materials. This serves as a design concept (interface switching) that modifies the mechanical properties near the adhesive interface rather than weakening the entire adhesive through light irradiation. Via this material design, they realized photo-responsive adhesive materials capable of selectively peeling off only the light-irradiated portions, restoring adhesion performance through ultraviolet irradiation at different wavelengths, and being used repeatedly.

Design concepts modifying mechanical properties of adhesive interfaces rather than changing entire adhesives not only facilitate disassembly, repair, and recycling of electronic equipment and automobiles but also enable recovery and reuse of adhesive materials themselves. In wide fields such as electronic equipment, mobility, and semiconductor packaging, the developed technology is anticipated to be a foundational technology supporting resource-recycling manufacturing. In the future, material designs based on dynamic polymer interfaces are expected to develop as foundational technologies supporting resource-circulating manufacturing and the creation of high-performance adhesive materials.

Takashima says, "While adhesive materials are indispensable for enhancing product performance, they also make disassembly and recycling after use difficult. We have been conducting research on photo-responsive elastomers utilizing reversible bonds. This material is characterized by the fact that only the elastic modulus of the irradiated surface changes upon light irradiation, and the material bends due to strain generated by differences in elastic modulus. Focusing on this property of 'being able to change the mechanical properties of only the irradiated surface,' we thought, 'if we can change the mechanical properties near the adhesive interface, we may be able to create a reusable adhesive that can be removed without leaving residue and without destroying the adhesive itself.' There have been few attempts to extend the design concepts of photo-responsive actuators to adhesive materials. This research is a materials design approach that achieves both adhesion and recyclability by optically controlling the mechanical properties near the adhesive interface through the equilibrium between molecular-level association and dissociation. In the future as well, by further developing the design concept of dynamic polymer interfaces promoted in JST CREST, and advancing applications to electronic materials, semiconductor packaging materials, and high-performance adhesive materials, we will contribute to the realization of a resource-circulating society."

Journal Information
Publication: Matter & Light
Title: Interfacial switching-driven photoactuator adhesives for selective peeling and substrate recycling
DOI: 10.1016/j.matlit.2026.100094