Restoration of superwetting switching on TiO2 coated shape memory polymer arrays

Recently, the switchable wetting surfaces between superhydrophobicity and superhydrophilicity have been widely studied. However, for almost all existing surfaces, especially inorganic responsive smart surfaces (TiO 2 , ZnO, etc.), their surface microstructures are easily damaged under external force, thus resulting in the loss of superwetting switching and corresponding functions. Realizing the restoration of the damaged surface microstructures would be promising to solve the problem, but it has never been reported. Herein, we advance a fresh strategy to solve the above question by combining shape memory polymer (SMP) and TiO 2 nanoparticles. The as-prepared TiO 2 coated SMP arrays have an excellent responsivity between superhydrophobicity and superhydrophilicity under alternation of UV irradiation and storage in dark. After pressing, the collapsed arrays can only achieve the limited wetting switching between hydrophobicity and hydrophilicity under the same treating condition. Importantly, SMP can help the collapsed surface microstructure recover the initial morphology based on its shape memory effect, and realizing the restoration of superwetting switching. The restorability is ascribed to the cooperative effect between the shape memory property of the SMP and UV-induced surface chemistry variation of TiO 2 nanoparticles. Furthermore, the restorable functional application in droplet storage is also demonstrated. This work provides a fresh idea for designing new smart superwetting surfaces.