Green-Light-Triggered Phase Transition of Azobenzene Derivatives toward Reversible Adhesives.

Studies on the azobenzene derivative based phase transitions mostly rely on photoisomerization, which require a long time to spontaneously revert back. Here we show a photothermal-driven solid-to-liquid transition and fast reversion of azobenzene derivatives. Owing to the aggregation of suitably substituted azobenzenes, solid-to-liquid transitions can be induced by photothermal effects under irradiation with green light. The liquid-state azobenzene derivatives spontaneously solidify again within 2 min due to heat release in a purely physical fashion. One thus obtains a perfectly reversible adhesion with a strength as high as that of commercial materials. Our work affords a novel concept to construct reversible adhesives via phase transitions of organic compounds induced by light.