3D flexible superhydrophobic polyphosphazene coated melamine sponge for oil–water separation

• Sponge@PZAF is prepared in one step by a simple and environmentally friendly method. • Sponge@PZAF is a low cost, non-toxic and biodegradable material. • Sponge@PZAF exhibits good oil absorption and fast absorption capacity. • Sponge@PZAF is reusable and has excellent oil retention capacity. The oil spill is still a great challenge, or even a disaster, for the ecological and environmental protection, especially over the offshore area. Here we reported a surface modification of sponge with Poly[cyclotriphosphazene-co-bisphenol AF] (PZAF), which is synthesized simply by one-step mixing of hexachlorocyclotriphosphazene (HCCP), bisphenol AF (BPAF), triethylamine precursors, for the efficient removal of oil from water at room temperature. Beause of the coverage of hydrophobic polymer on the surface, the modified sponge (i.e., Sponge@PZAF) has a high water contact angle (WCA) of 153 o and a high adsorption capacity of 71.04 - 135.19 g g -1 for various oils and organic solvents within 30 seconds. The fine three-dimensional mesh structure of the sponge contributes to oil adsorption, which allows the oil to fill the entire chamber efficiently and quickly. After oil adsorption-desorption recyclings for ten times, the adsorption capacity of the used Sponge@PZAF is still as high as 69.76 - 132.44 g g -1 , which indicates the good recyclability of the sponge. The Sponge@PZAF exhibits underlyingly industrial potential in the field of purificating oil-containing water such as offshore oil spill, wastewater from oil and steel industries.