A composite oil/water separating material integrating switchable superhydrophobicity/superhydrophilicity with tunable pore size

Abstract

Recently, applying superwetting materials in separating oil/water mixtures has attracted considerable attention. Generally, effective separation of emulsions requires materials with small pore size to match emulsion size. Regrettably, when applied to separate immiscible oil/water mixtures, such materials would compromise flux performance. Herein, a composite separation material composed of a pH-responsive metal mesh and a superlyophilic shape memory polymer (SMP) sponge was designed. This separation material exhibits tunability in both pore size and surface wettability. The copper mesh demonstrates switchable superhydrophobicity/superhydrophilicity responsive to water pH, which offers selective removal of water or oil. More importantly, the SMP sponge offers dynamic control over pore size ranging from 895 μm to 450 nm owing to its shape memory capability. This allows highly efficient separation of both immiscible oil/water mixtures and emulsion by tailoring the pore size accordingly. The material can avoid the above-mentioned problem about the flux sacrifice. This work reports a new oil/water separation material with adjustability in both surface wettability and pore size, which can not only realize selective oil/water separation, but also provide distinct pore size for immiscible oil/water mixtures and emulsion, respectively. Given such advantages, the strategy advanced here may provide some fresh ideas for designing advanced oil/water separating materials.