Fluorine-Free Superhydrophobic Coatings: Rapid Fabrication and Highly Efficient Oil/Water Separation

In this work, a rapid method is demonstrated to obtain a fluorine-free superhydrophobic/superoleophilic coating by a simple two-step method: dip-coating and oven curing. The chemical structure of the coating is based on the crosslinking reaction of an alkyl methacrylate, a dimethacrylate (crosslinker) and a silane (adhesive), using AIBN as initiator, toluene as solvent, and silica nanoparticles to enhance surface roughness. Chemorheology results show that the coating is fully cured even in 20 min at 100 degrees C, exhibiting a water contact angle (CA) of 162 +/- 2 degrees, sliding angle (SA) of 4 +/- 1 degrees, nanometrical structures throughout the surface, and excellent adhesion properties for the mesh screen. The coating exhibits outstanding oil/water separation efficiency (96-99%) for seven different types of oil (gasoline, diesel, petroleum ether, hexane, toluene, chloroform, and dichloromethane), and in addition presents high recyclability. Based on nonisothermal TGA, the activation energy of degradation, calculated using the Kissinger and Ozawa models, is 113.5 and 114 kJ mol(-1), respectively. Finally, the coating is thermally aged at 150 degrees C: the CA exhibits a smooth decrease up to 129 +/- 1 degrees at 120 min, and FTIR analysis shows structural changes possibly related to the generation of thermal oxidation products.