Durable superhydrophobic/superoleophilic PDMS sponges and their applications in selective oil absorption and in plugging oil leakages

A facile method for preparing porous polydimethylsiloxane (PDMS) sponges is reported. The PDMS sponges are fabricated by the polymerization of the PDMS prepolymer and a curing agent in dimethicone using NaCl microparticles as the hard templates. The porous structure of the PDMS sponges is controllable simply by regulating the weight ratio of prepolymer to dimethicone and the size of the NaCl microparticles. The PDMS sponges feature high compressibility and stretchability, excellent superhydrophobicity/superoleophilicity, as well as high chemical and thermal stability. The PDMS sponge can completely recover its original shape even after 50 cycles of 90% strain. The elongation at breaking the sponge is as high as 97%. The PDMS sponge is superhydrophobic with a water contact angle of 151.5 degrees but can be easily wetted by oils. The sponge also exhibits excellent repellency to corrosive aqueous liquids. The flexibility and superhydrophobicity of the sponge remain unchanged even after keeping in liquid nitrogen or at 250 degrees C for 24 h. Long-term immersion in various organics has no obvious influence on superhydrophobicity, oil absorbency, or weight of the sponge. The PDMS sponge can selectively absorb a large amount of floating oils on the water surface and heavy oils under the water, and furthermore, is reusable. Moreover, the PDMS sponge swells quickly after the adsorption of oils, which makes it a promising material for plugging oil leakages.