Micro-nano surface structure construction and hydrophobic modification to prepare efficient oil-water separation melamine formaldehyde foam

Abstract A superhydrophobic melamine formaldehyde foam (SMF) was fabricated via a simple green solution-dipping method in polyvinyl alcohol (PVA) aqueous solution and polydimethylsiloxane (PDMS) ethanol one respectively. The resulted phase-separated PVA during transferring MF from aqueous solution to ethanol one, can form micro-nano structure on MF skeleton, thus endowing the foam surface with considerable roughness. Along with the crosslinking of PDMS, hydrophobic coating on the surface was formed. The modified foam exhibited superhydrophobicity (water contact angle at 157° and water sliding angle at 7°). Its absorption capacity to different organic solvents was evaluated. Meanwhile, a simple device for oil-water separation by connecting the modified foam block with a vacuum system was designed to testify the oil-water separation efficiency. In addition to excellent oil-water separation ability, the modified foam also showed good compressive performances including excellent corrosion resistance with pH of solutions ranging from 1 to 13, remarkable recyclability (up to 150 cycles), improved mechanical properties and high flame retardancy. Compared with the conventional porous superhydrophobic absorbents involving complicated methods and nanomaterials, such efficient SMF fabricated via a simple, low-cost and eco-friendly way shows promising prospect in dealing with oil spillage and industrial organic pollution in the future.