The inefficacy of repelling water droplets laden with macromolecules (complex droplets or diluted polymer solution) is a long-standing shortcoming of superhydrophobic surfaces, which severely limits their reliability in practical applications. Here, we design a surface termed the superhydrophobicity–slipperiness switchable surface (3S surface), which demonstrates superhydrophobicity at room temperature and slipperiness when heated. The 3S surface is composed of magneto-responsive wires coated with superhydrophobic nanoparticles and impregnated with thermoresponsive paraffin, exhibiting lotus leaf-inspired passive water repellency and respiratory cilia-inspired active water repellency at room temperature. When heated, the impregnated paraffin melts and forms a lubricant layer atop the surface structures, exhibiting the pitcher-plant-inspired removal of complex droplets that remain pinned on conventional superhydrophobic surfaces. The counterintuitive integration of superhydrophobicity (a liquid–solid–gas composite system) and slipperiness (a liquid–lubricant–gas system) into a surface and the on-demand switch between them are not only important to the applicability of self-cleaning surfaces to real-world environments, where complex liquids are inevitable, but also provide insights into various interface-related applications.
Versatile surfaces demonstrating multiple interfacial functionalities are highly demanded as a surface typically serves various duties and faces multiple challenges in real practice. However, such versatile surfaces are rarely reported mainly due to the challenges in integrating multiple structural characteristics. Here, by mimicking lotus leaves, butterfly wing, and respiratory cilia, we develop a surface termed wire-on-pillar magneto-responsive superhydrophobic arrays (WP-MRSA), which possess interfacial properties of structural superhydrophobicity, anisotropicity, stimuli responsiveness, and flexibility. By combining soft lithography and self-alignment of iron-laden aerosols under a magnetic field, iron-laden wires are planted atop prefabricated pillar arrays, resulting in well-ordered, sparse, high-aspect-ratio, flexible, and superhydrophobic wires, which largely deflect in response to a magnetic field. This unique integration of structural properties and configurations enables various functionalities, such as on-demand control of droplet impact dynamics, real-time regulation of surface lateral adhesion force, fast removal and sorting of objects, and precise manipulation of droplets for selective reactions. Those functionalities benefit various applications especially droplet-based microfluidics and active self-cleaning surfaces.
危险品化学品经营许可证（带存储）