Superhydrophobic modular cryogel with variable magnetic-actuated motion direction for discrete small-scale oil spill cleanup

Smart superhydrophobic sorbents are in high demand for cleaning oil spills that could endanger the aquatic ecosystem. Herein, we demonstrated the fabrication of a superhydrophobic and magnetic modular cryogel (SNS@Fe-PSC) containing three starch-based modules, namely, a superhydrophobic nano-coating, a magnetic nanocomposite insertion, and a high-strength starch/polyvinyl alcohol composite substrate. The surface chemical composition and hierarchical micro/nanostructures of this material were investigated in detail. The modular cryogel had a high water contact angle (151 degrees) and low sliding angle (<9 degrees), as well as excellent water-repellent, self-cleaning, and anti-fouling properties. This material also exhibited good durability owing to its stable chemical bonding and structural support. SNS@Fe-PSC could be applied to remove oil from water effectively. Moreover, the magnetic module (saturation magnetization, 5.04 emu/g) allowed the as-obtained material to be propelled and controlled by a magnet on the surface of water. Variable magnetic-actuated motion direction could be realized by adjusting the position and amount of magnetic modules inserted to the cryogel.