Sunlight Recovering the Superhydrophobicity of a FemtosecondLaser-Structured Shape-Memory Polymer

Superhydrophobic surfaces have aroused increasingattentions in thefields of self-cleaning, anti-fouling, heat transfer, etc.However, one of the major problems of the artificial superhydrophobicsurface in practical applications is the poor durability. Inspired by theself-healing property of nature organism, we developed a sunlight-driven recoverable superhydrophobic surface by femtosecond laserconstructing micropillar array on the surface of the photo-responsiveshape-memory polymer (SMP). The photo-responsive SMP compositewas prepared by adding reduced graphene oxide (RGO) into thermal-responsive SMP matrix. Due to the excellent sunlight-to-heattransformation property of RGO, the temperature of the as-fabricatedRGO-SMP composite could be rapidly increased above the shapetransformation temperature of the RGO-SMP under one sunlightirradiation. Once the micropillar array of the RGO-SMP composite was deformed by pressing or stretching treatments, the surfacewould lose superhydrophobicity. Upon sunlight irradiation, the surface morphology and the wettability of the RGO-SMPmicropillars could completely recover to the original states. Meanwhile, this reversible morphology and wettability transformationprocess could be repeated multiple times. We envision that such a sunlight-recoverable superhydrophobic surface will have greatapplications in the future.