Mosquito's eyes inspired, hydrophobic and multifunctional coating on flexible polyurethane (PU) foam: highly efficient oil spills remediation and exceptional flame-retardant performance

Abstract

Inspired by the structure of mosquito's compound eyes, a hydrophobic flexible polyurethane (PU) foam composite (named as PU@SiO2/ADP) with good flame-retardant property was fabricated by coating aluminum diethylhypophosphite (ADP) and in situ-formed SiO2 nanoparticles. Owning to considerable surface roughness of stacked SiO2 nanoparticles and intrinsic hydrophobicity of ADP, the water contact angle (WCA) of modified PU foam increased from 113° to 133°. The absorption capacity of modified foam to oils and organic solvents was also evaluated. The results showed that the absorption ratios of the modified PU to dichloromethane reached 69 g/g. The oil-water separation results proved that PU@SiO2/ADP foam could rapidly and selectively absorb oils or organic solvents from the water surface even under turbulent flow conditions. Fabricated hydrophobic PU maintained excellent oil absorption properties after 10 absorption-squeezing cycles, demonstrating good recyclability. The modified PU foam also showed high flame retardancy. The surface treatment method applied in this research not only provides an effective strategy for fabricating a promising absorbent PU foam for oil spill treatment, but also brings a promising prospect for enhancing the flame-retardant performance of these absorbent polymer composites. This work provides support and reference for the improvement of similar materials in future works.