Fluoroalkylated Azobenzenes with Photoswitchable Solid–Liquid States Enabling Spatiotemporally Controlled Lubrication for Liquid Motion Manipulation

ABSTRACT

The precise control of liquid motion with light is fundamental to advancing next‐generation microfluidic devices and microreactors. Fluoroalkylated photoswitches that combine low surface tension with photoinduced reversible solid‑to‑liquid transitions would be ideal for this purpose, yet they have remained unrealized because fluoroalkyl chains typically suppress solid‑state photoisomerization. Here, we overcome this limitation by designing fluoroalkylated azobenzenes that exhibit low surface tension and photoinduced reversible solid‑to‑liquid transitions. This dual functionality stems from tailored molecular and crystalline structures that enable efficient trans ‐ cis photoisomerization in the solid state. The fluoroalkylated azobenzenes function as non‑lubricating solids in their trans form and become liquid lubricants upon photoconversion to their cis form. By infusing them into microstructured substrates, we create surfaces that can be optically switched between a liquid‐pinning state and a slippery state. This photoswitching capability enables the on‑demand creation and reconfiguration of guiding pathways to control the sliding of various liquids. This work establishes spatiotemporally controlled lubrication via photoinduced reversible solid‑to‐liquid transitions as a new mechanism for designing microfluidics, microreactors, and adaptive surfaces.