Simple Fabrication of PDMS-Grafted Hydrophobic Iron Oxide Particles for Oil-Water Separation and Stimuli-Responsive Liquid Marbles

In this paper, poly(dimethyl siloxane) (PDMS) which is considered chemically unreactive was successfully grafted onto the surface of iron oxide particles, forming stable hydrophobic polymer-coated particles without the usage of any external stimuli like heat or UV irradiation. Here, magnetic hydrophobic particles were prepared by a facile method of coating PDMS prepolymer oil onto Fe3O4 particles via dispersion in a PDMS oil/hexane solution. The X-ray diffraction studies elucidated the successful synthesis of the magnetic particles, whereas the X-ray photoelectron spectroscopic studies ensure the successful incorporation of the polymer layer onto the particles. Two potential applications of the prepared particles were demonstrated here. The oleophilic and hydrophobic nature of the particles coated with PDMS is exploited to demonstrate the oil collection from the surface as well as in immersed conditions in an aqueous medium by using the particle-coated cotton and sponge, respectively. An oil-water separation efficiency of similar to 95% was achieved for cotton and sponge against various oils with an oil adsorption capacity of 5 times and 11 times its own weight, respectively. Additionally, magnetic-responsive liquid marbles (LMs) were prepared by encapsulating liquids with the fabricated particles. Stable LMs were formed for a wide range of volumes (5-200 mu L) with core liquids having different surface tensions, pH, and viscosity. The stability of the LM was tested using a dropping method and a hydrostatic pressure method.