A novel epoxy-based self-healing robust superhydrophobic coatings for oil/water separation

Low durability greatly limits the practical application of superhydrophobic coating. In this study, we report a method of employing low surface energy materials and chemically reactive epoxy groups that possess strong adhesion on substrates in one system to solve the durability issue. A branched epoxy with dangling long polydimethylsiloxane (PDMS) tail was first synthesized through a thiol-Michael addition reaction. After curing, this coating exhibited superhydrophobicity with the contact angles (CAs) of 162.8 ± 1.0° and excellent durability towards strong acid (pH = 1.0), organic solvents as well as thermal treatment (150 °C, 24 h). Notably, the CAs of this coating could maintain above 150° after 80 times of sandpaper abrasions, 100 times of tape-peeling, and 240 min of ultrasonic treatment, respectively. More importantly, the coating could spontaneously revert to a superhydrophobic state at room temperature after being plasma-treated to a superhydrophilic state. The coating fabric was utilized to separate the mixture of oil/water and the efficiencies for blend oil, corn oil, and soybean oil were found to be 97.7 ± 0.4 %, 98.2 ± 0.5 %, and 98.7 ± 0.3 %, respectively. This work provides a novel strategy to create a fluorine-free, self-healing, and robust superhydrophobic coating.