Hydrophobic surface to hold a water droplet by cholesterol-based organogel with solvent-tuned morphologies

Abstract

In this paper, half-tubes, micro-wires and ribbons were constructed in a simple cholesterol-based organogel by varying polar gelation solvents such as acetonitrile, isopropanol, and ethanol. All of them showed hydrophobic surfaces with water contact angles more than 140°. Moreover, the interlaced micro-wires obtained from isopropanol were of 500 μm in length, which could hold a water droplet even at an 80° incline. The formation and the characterization of the half-tube were followed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). X-Ray diffraction (XRD) and UV-vis spectra revealed that the aggregates were constructed by dimers of the molecules with H aggregates in the layer structure. It was proposed that hydrogen bonding, hydrophobic interactions, π–π stacking as well as solvent molecules played an important role in the assembly.