When it comes to making glue, manufacturers must find a balance between making the sticky substance strong enough to hold, but easily pulled apart. That’s because boosting one attribute usually weakens the other. As a result, the end product is either not sticky enough or so strong it can't be removed when it's no longer needed. Now, scientists in Japan have created an intriguing, reusable glue that can be instantly stuck on and taken off, without weakening either. The secret to the new adhesive lies in caffeic acid — an organic compound found in foods like coffee and apples. It reacts differently under various ultraviolet and light wavelengths, allowing the glue to stick and to be removed and used again. The glue was tested several times, once using it to hold up an 88-pound weight for 72 hours. It was also used to mend cracked silicone tubes, which remained leak-free even when high-pressure water was run through them. Beyond it’s novel stick-unstick ability, this breakthrough may also help reduce waste. Products could potentially be dismantled into components at the end of their useful life and transformed into new ones.
