Palygorskite@Fe3O4@polyperfluoroalkylsilane nanocomposites for superoleophobic coatings and magnetic liquid marbles

Abstract

Superoleophobic coatings and remotely controllable liquid marbles are of great interest in many fields. Here, we report the preparation of magnetic nanocomposites that can be used for the fabrication of superoleophobic coatings and magnetic liquid marbles from both water and organic liquids with surface tension as low as 22.85 mN m⁻¹. The nanocomposites were prepared by growing Fe₃O₄ nanoparticles on the needle-like crystals of palygorskite (PAL) via modified solvothermal reduction reactions between FeCl₃ and ethylene glycol, and then coated by hydrolytic condensation of 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTES) and tetraethoxysilane (TEOS). The nanocomposites were characterized using a wide range of electron microscopy and other analytical techniques. The growth of Fe₃O₄ nanoparticles on PAL not only provides magnetic responsivity, but also constructs a hierarchical micro/nanostructure. The coatings with tunable wettability and liquid marbles encapsulated with liquids of different surface tensions were obtained simply by controlling the surface topography and surface chemical composition, in other words, the volume ratio of PFDTES to TEOS. The superoleophobic coatings show high contact angles and low sliding angles for various organic liquids such as n-hexadecane, toluene, n-dodecane, etc. The liquid marbles feature excellent magnetic responsivity, high stability and a very thin layer of solid powder.