Sunlight Recovering the Superhydrophobicity of a Femtosecond Laser-Structured Shape-Memory Polymer

Superhydrophobic surfaces have aroused increasing attentions in the fields of self-cleaning, anti-fouling, heat transfer, etc. However, one of the major problems of the artificial superhydrophobic surface in practical applications is the poor durability. Inspired by the self-healing property of nature organism, we developed a sunlight-driven recoverable superhydrophobic surface by femtosecond laser constructing micropillar array on the surface of the photo-responsive shape-memory polymer (SMP). The photo-responsive SMP composite was prepared by adding reduced graphene oxide (RGO) into thermal-responsive SMP matrix. Due to the excellent sunlight-to-heat transformation property of RGO, the temperature of the as-fabricated RGO-SMP composite could be rapidly increased above the shape transformation temperature of the RGO-SMP under one sunlight irradiation. Once the micropillar array of the RGO-SMP composite was deformed by pressing or stretching treatments, the surface would lose superhydrophobicity. Upon sunlight irradiation, the surface morphology and the wettability of the RGO-SMP micropillars could completely recover to the original states. Meanwhile, this reversible morphology and wettability transformation process could be repeated multiple times. We envision that such a sunlight-recoverable superhydrophobic surface will have great applications in the future.