A bio-inspired green method to fabricate pH-responsive sponge with switchable surface wettability for multitasking and effective oil-water separation

Smart oil-water separation materials with stimuli-responsive wettability surfaces have attracted wide attention. In this paper, a novel, simple and low-cost method is developed to prepare a pH-responsive melamine sponge (MS) with switchable wettability . This approach involves the hydrophobic modification of hexadecyltrimethoxysilane (HDTMS) on the MS surface modified by polydopamine (PDA) and the Michael addition reaction and Schiff base reaction between 12-aminododecanoic acid (NH 2 (CH 2 ) 11 COOH) and PDA. Hydrophobic/oleophilic HDTMS and pH-triggered NH 2 (CH 2 ) 11 COOH enable the functionalized sponge to repeatedly switch between the two extreme wettability under different pH environments. Benefiting from the excellent 3D porous surface structure and smart wettability, the as-prepared sponge can be applied in the on-demand separation of various oil-water mixtures by adsorption or filtration with a separation efficiency over 98.5% and high absorption capacity of 72.7–161.3 g·g −1 . With the assistance of pump-driven, continuous adsorption separation can be achieved in two cases by utilizing the wettability transformation. Moreover, in an alkaline solution, the sponge can quickly release most of the absorbed oil, showing a controllable desorption process. This smart wettability material with simple preparation and green has application potential in controllable oil-water separation and on-demand oil-spills treatment.