Nonflammable and Magnetic Sponge Decorated with Polydimethylsiloxane Brush for Multitasking and Highly Efficient Oil–Water Separation

Abstract Developing sponge materials integrating excellent flame retardancy, multitasking separation performance, and efficient emulsion‐breaking ability is significant but challenging for the remediation of oil spills causing fires and environmental damages. Herein, a superhydrophobic oil–water separation sponge material, containing a melamine‐formaldehyde (MF) sponge substrate, magnetic polydopamine (PDA) coating, and branched polydimethylsiloxane (PDMS) brush, through dopamine‐mediated surface initiated atom transfer radical polymerization (SI‐ATRP) is fabricated. The synergistic flame resistance of the MF substrate and PDMS brush significantly improves its adaptability in fire. More importantly, the decorated PDMS brushes can effectively overcome the size mismatch between sponge macropores and tiny emulsified droplets, while remaining the intrinsic macroporous characteristic. When treating W/O emulsions, the PDMS brushes stretch up to act as “interface‐breaking blades” to accelerate the coalescence of emulsified water droplets. Meanwhile, such PDMS brushes can serve as “oil‐trapping tentacles” to efficiently capture oil droplets when treating O/W emulsions. Such material design synergistically contributes to satisfactory separation efficiency (98.7%) and ultrahigh permeation flux (up to 1.35 × 10 5 L m −2 h −1 ), even for treating high viscosity emulsions. Besides, the reported sponge also inherits robust durability, superior recyclability, and convenient magnetic collection. These features make the sponge promising for multitasking and highly efficient oil–water separation.