Novel multifunctional solid slippery surfaces with self-assembled fluorine-free small molecules

Abstract

Functional slippery surfaces have broad applications in engineering and bioengineering processes, such as water harvesting, photocatalysis, wastewater treatment and food industry. In this work, for the first time, we report the fabrication of a novel type of functional slippery solid surfaces via the self-assembly of a non-fluorine small molecule, γ-mercaptopropyldi(trimethylsiloxy)methylsilane (MD(SH)M), which possess liquid-like slippery features. This new strategy avoids the requirement and fabrication of complex micro-/nano-scale surface structures and infused lubricant oils in conventional slippery surfaces. The as-prepared functional MD(SH)M surfaces allow facile transport of bubbles in aqueous media and water drops in oil, as well as facilitate the self-assembly of nanoparticles from their aqueous suspensions. The transport of air bubbles and water drops is driven by the buoyancy force or gravity force, against the sliding resistance associated with the bubble-solid-water or drop-solid-oil three-phase contact line. The functional slippery surfaces with lower surface energy and contact angle hysteresis show higher velocity of transporting bubbles/drops under the same test conditions, demonstrating better slippery behavior. The as-prepared functional slippery solid surfaces allow the three-phase contact line to move more freely as compared to the conventional lubricant liquid-infused slippery surfaces. This research provides a new and facile strategy for the fabrication of novel slippery coatings without the need of complex micro-/nano-scale surface structures and infused lubricant oils, with great potential applications in many engineering and bioengineering processes wherever low friction forces are desired.