A research team from The University of Osaka has created a prototype adhesive that can be selectively removed from a surface when exposed to light, without leaving any visible residue. This innovative adhesive can be reused multiple times by heating and using a different ultraviolet (UV) light wavelength to reset its molecular structure. The findings were published in the journal Matter & Light. The adhesive is made using a special design that includes reversible molecular links between two compounds: stilbene and triacetylated beta-cyclodextrin. These links act like tiny, flexible connectors that can be temporarily broken and reformed. When exposed to UV-A light (365 nm), the stilbene molecules undergo a chemical change called photoisomerization, which weakens the molecular links near the surface. This weakening reduces the adhesive's strength by about 45%, allowing it to be peeled off cleanly without leaving behind any sticky residue. When a different UV light, specifically UV-C (254 nm), is used, the molecular links are restored, and the adhesive regains its strength. This process of switching adhesion on and off using light was repeated successfully through 15 cycles of peeling and rebonding. The adhesive could be reactivated simply by heating, without the need for any chemical solvents. Using a technique called atomic force microscopy, the researchers confirmed that the surface stiffness and adhesion properties changed reversibly with each light exposure. This new adhesive design could significantly simplify the disassembly, repair, and recycling of electronic devices, automotive parts, and semiconductor components. By allowing adhesion to be controlled at the surface level rather than damaging the adhesive itself, the technology offers a promising approach for creating more sustainable and reusable products. The study's senior author, Yoshinori Takashima, explained that the team aimed to explore whether adjusting the stiffness of an adhesive interface with light could enable clean peeling without destroying the adhesive. He hopes this concept will lead to new adhesive technologies and support more circular, environmentally friendly manufacturing practices.