Fluorine-free superhydrophobic PDMS-coated silica particles for oil–water separation and liquid marbles.

In this paper, we report the fabrication of fluorine-free hydrophobic particles via grafting fluidic polydimethylsiloxane onto silica particles through a facile wet lab technique at room temperature. A cotton fabric coated with the prepared hydrophobic particles shows potential as a membrane to separate oil and water due to hydrophobic behavior (equilibrium water contact angle ~ 145°) and superoleophilicity. The hydrophobic nature of the fabric is varied only slightly after immersing the fabric in 1 M of acidic and basic solution for seven days and thus ensured the chemical stability of the fabric, whereas the physical stability examined via abrasion test elucidates minimal change in wettability even after 50 cycles of abrasion tests. The oil–water separation efficiency of the membrane made from particle-coated cotton fabric is found to be greater than 95% even after 50 cycles of usage for various oils. Further, these particles are used to cover aqueous droplets to create liquid marbles. The stability of the liquid marble is investigated against solution with different surface tension, pH values, and viscosity. The particles demonstrate the potential to create stable liquid marbles even when the surface tension of liquid is as low as ~ 32 mN m−1. In addition, the liquid marbles are created from aqueous solutions having pH values ranging from 1 to 14 and with liquids having viscosity over a wide range. The substrate temperature-dependent evaporation studies of the liquid marbles unambiguously elucidate the porous nature of the surface and manifest a temperature-dependent liquid marble height decrease in evaporation time scale. [ABSTRACT FROM AUTHOR]