Smart surfaces with reversibly switchable wettability: Concepts, synthesis and applications

As a growing hot research topic, manufacturing smart switchable surfaces has attracted much attention in the past a few years. The state-of-the-art study on reversibly switchable wettability of smart surfaces has been presented in this systematic review. External stimuli are brought about to render the alteration in chemical conformation and surface morphology to drive the wettability switch. Here, starting from the fundamental theories related to the surfaces wetting principles, highlights on different triggers for switchable wettability, such as pH, light, ions, temperature, electric field, gas, mechanical force, and multi-stimuli are discussed. Different applications that have various wettability requirement are targeted, including oil-water separation, droplets manipulation, patterning, liquid transport, and so on. This review aims to provide a deep insight into responsive interfacial science and offer guidance for smart surface engineering. It ends with a summary of current challenges, future opportunities, and potential solutions on smart switch of wettability on superwetting surfaces. [Display omitted] •Advances on smart surfaces with reversibly switchable wettability are critically reviewed.•Fundamental theory behind switchable wetting and the inherent principles for smart surfaces are presented.•The influence of various external stimuli on tunable wetting state is highlighted and discussed.•Promising applications with on-demanded wettability requirement are targeted.•A summary of current challenges, future opportunities and potential solutions on superwetting surfaces are proposed.