Molecularly engineered under-liquid dual superlyophobic coatings for efficient and on-demand oil/water separation

Surfaces exhibiting under-liquid dual superlyophobicity (combined underwater superoleophobicity and underoil superhydrophobicity) hold immense potential for intelligent oil/water separation systems, yet their realization remains thermodynamically constrained. Herein, we proposed an interfacial hydrophilic/hydrophobic chain regulation strategy that synergistically constructed an under-liquid dual superlyophobicity coating via integrating dynamic interfacial chain reorganization with multiscale structural. By programmatically regulating hydrophobic chain lengths in amphiphilic molecules, precise control over the adaptive conformational switching of self-assembled monolayers on hierarchically nanostructured substrates was achieved to tune membrane macroscopic wettability. The coating exhibits reversible wettability transitions between underoil superhydrophobic and underwater superoleophobicity, which is consistent with the dynamic molecular reconfiguration of environment-responsive molecular chains. Consequently, the coated-porous membrane, with under-liquid dual superlyophobicity, exhibits over 99 % separation efficiency for light/heavy oil/water mixtures and emulsions, especially in long-term on-demand separation of emulsions. This practical and simple strategy provides a versatile platform for developing smart materials for on-demand treatment of complex oily wastewater.