Fabrication of dual-sensitive heterogeneity organohydrogel with temperature/surrounding-phase regulatory superomniphobic surface for on-demand oil/water separation

Abstract Oil/water separation is difficult but essential not only for the sustainable development of human society but also for the protection of the ecological. Developing materials with controllable wettability for efficient on-demand oil/water separation is urgently needed. Inspired by the structural and functional features of the cellular plasma membrane, in this work, a dual-sensitive heterogeneity organohydrogel was fabricated by combining thermal-responsive poly(N-isopropylacrylamide) (PNIPAM) and reactive polysiloxane particles (RPP). The resulting organohydrogel can adapt to temperature stimuli to realize super-wettability conversion (from superhydrophilicity (WCA is 0°) to superhydrophobicity (WCA is ∼160.5°) under-oil). In the dry state, the wettability of organohydrogel can also be adjusted to superamphiphobicity under water (OCA is ∼151.5°) or under oil (WCA is ∼162.4°) after being pre-wetted with water or oil. In addition, the outstanding film-forming property of the organohydrogel led to the formation of a coating layer on fiberglass fabric. Exhilaratingly, the coated fiberglass fabric displays stable recyclability, excellent chemical tolerance, and temporal stability, as well as demonstrates an excellent super-wettability conversion even after 90 cycles of the peeling test. Under different pH solutions, the WCA on the coated material surface was always 0° at 20 °C, while the measured WCA was always above 150° at 45 °C. Moreover, the coated fiberglass cloth could achieve on-demand oil/water mixture separation and selective separation efficiency above 98.5%. Thus, our work may pave the new ideas in the application of on-demand oil/water separation and oily wastewater purification in the further.