Superhydrophobic Melamine Sponge Modified by Cross-Linked Urea Network as Recyclable Oil Absorbent Materials

A novel urea cross-linking reaction, involving the facile reaction between urea amide and isocyanate groups of an isocyanate-terminated poly(dimethylsiloxane) (iPD), was employed to fabricate superhydrophobic melamine sponge (SMS) as an efficient oil- and organic-solvent-absorbent material. By heating, isocyanate terminals of iPD can react with the secondary amine groups of melamine sponge (MS), rendering covalent urea bonds over the surface of MS skeleton. The resultant SMS exhibits a high water contact angle (WCA) of 153.4 degrees, excellent volumetric absorption capacity (1.163-1.661 m(3)/m(3)), superior selectivity, and high absorption capacity retention (85.1-98.7%) over 30 sorption-squeezing cycles for different oils and organic solvents. The fabrication procedure of SMS is simple and cost-effective, and the robust, recyclable SMS is efficient in the separation of various oils and organic solvent/water mixtures. Therefore, a readily available process for environmental cleanup and remediation was provided in this study.