Light-Switchable Adhesion of Azobenzene-Containing Siloxane-Based Tough Adhesive

An azobenzene-containing siloxane-based adhesive polymer was synthesized with azobenzene moieties as hard segments and siloxane moieties as soft segments. Upon UV irradiation, the adhesive energies decreased to 1.9% of the original values, and subsequent green light exposure raised adhesive energies to 98.3% of the original values. The light-switchable adhesion was applicable to various substrates. Attractively, a polymer-glued plastic ring could be reversibly opened and closed by respective exposure to UV and green light with pressure on the adhesive position. Such a strategy may be applicable for designing light-switchable tough adhesives.