Adhesives are useful, but once most of them set, that's it — you're committed. Removing them usually means heat, solvents, or just tearing things apart. A team of researchers at Japan's National Institute of Advanced Industrial Science and Technology (AIST) has come up with something fundamentally different: an organic adhesive that can be switched between solid and liquid states simply by shining light on it.
The material works through a photochemical isomerization reaction. When exposed to UV light in the 365–385 nm range, the compound transitions from a solid adhesive state to a liquid. Shine green light on it and it solidifies again — ready to bond once more. The whole process is reversible and can be repeated many times, with no need for heat, cooling, or any chemical treatment. Just light.
How It Works
The underlying mechanism involves molecules that change their shape when they absorb specific wavelengths of light — a process called photoisomerization. In the solid phase, the molecules pack together in an ordered crystalline structure that gives the material its adhesive properties. UV light triggers a molecular flip that disrupts this packing and causes the material to melt into a liquid. Green light reverses the flip, and the material recrystallizes and becomes sticky again.
The fact that this works at room temperature without any thermal input is what makes it practically interesting. Many shape-changing or phase-change materials require significant temperature changes, which limits their usefulness in applications where precise control is needed.
Potential Applications
A reusable, light-switchable adhesive could find uses in electronics assembly, where components sometimes need to be attached and detached precisely without damage. It could also work in medical devices, precision optics mounting, and any situation where adhesion needs to be temporary and controllable. The fact that it uses only light — a clean, contactless stimulus — makes it particularly appealing for delicate or enclosed systems.
Check out the video below to see the material in action:
Source: Physics World
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