Self-stratifying coating enables facile fabrication of robust superhydrophobic sponges for oil-water mixture separation

Superhydrophobic polymer sponges are a promising solution to the serious environmental crisis caused by oil spills in modern society, given their excellent sorption capacity and high selectivity, if designed well. However, realizing such hydrophobic sponges in an eco-friendly, easy, and cost-effective way is still a challenging task, despite several reported methods. Here, we report a facile approach to obtaining a superhydrophobic sponge using self-stratifying coating technology. The process briefly involves dip coating a pre-made commercial sponge in our prepared self-stratifying resin, followed by curing. The prepared superhydrophobic sponges showed excellent oil sorption capacity towards various organic solvents, with adsorptive capacity values ranging from similar to 100 to 200 g/g and the capability to be reused >20 times with an adsorption retention capacity of above 95 % of the first cycle. In addition, the modified sponge presented good mechanical stability and thermal stability (up to 350 degrees C). With the advantages of the fabrication method and the benefits in oil-water separation, the modified sponge has promising applications in the field of oil spill treatment and environmental remediation.