Controllable photo-switching of cinnamate-based photonic films with remarkable stability

In this work, a cinnamate derivative has been synthesized and infiltrated into a silica colloidal crystal template together with methyl methacrylate and ethylene glycol dimethylacrylate to construct cinnamate-based inverse-opal films. The resulting cinnamate-based photonic films can undergo reversible [2 + 2] photo-cycloaddition under ultraviolet light with different wavelengths (365 nm for cyclization and 254 nm for cleavage). Interestingly, we found that the photo-induced states of these photonic films possess more remarkable temporal and thermal stability than the reported ones based on azobenzene and spirobenzopyran derivatives. The magnitude of the shift of the Bragg diffraction peaks is also tunable, depending on the ratio of methyl methacrylate and ethylene glycol dimethylacrylate. These cinnamate-based photonic films have the potential to serve as binary systems for optical data storage, and the data stored on photonic films can be read out by detecting the reversible alternative Bragg diffraction wavelengths.