CO₂‐Responsive Nanofibrous Membranes with Switchable Oil/Water Wettability

Abstract

Responsive polymer interfacial materials are ideal candidates for controlling surface wetting behavior. Here we developed smart nanostructured electrospun polymer membranes which are capable of switching oil/water wettability using CO2 as the trigger. In particular, the combination of CO2 -responsiveness and porous nanostructure enables the as-prepared membranes to be used as a novel oil/water on-off switch. We anticipate that the promising versatility and simplicity of this system would not only open up a new way of surface wettability change regulation by gas, but also have obvious advantages in terms of highly controlled oil/water separation and CO2 applications.

Energetically efficient electrochemically tunable affinity separation using multicomponent polymeric nanostructures for water treatment

“…18 In another example, suspended core-shell nanoparticles with adsorbed organic pollutants can lose colloidal stability and form macroscopic aggregates upon irradiation with ultraviolet light, allowing easy handling of bulkier materials as opposed to suspended nanomaterials. 4 ''Smart'' systems with hydrophobicity tunable by external signals such as pH, 19 chemical redox agent 20 and CO 2 concentration 21 have also been developed for organics-water separation.…”

“…ETAS is expected to show higher energy efficiencies and incur lower environmental costs than established methods for separation of neutral organics from water such as distillation, stripping, extraction, adsorption and filtration. [11][12][13] It operates at ambient temperature and pressure, requires no need for 21 -responsive systems that exhibit only two levels of hydrophobicity (i.e., merely ''on/off'' bimodal control), ETAS can achieve multiple levels of hydrophobicity and thus affinity towards organics since the electrical signal (i.e., potential) can be tuned with high precision, permitting a systematic adjustment of the ratio between the hydrophobic and hydrophilic moieties. Such flexible modulation of affinity for target pollutants is key to achieving a balance between the separation degree and the energetic efficiency, as discussed later.…”

External‐Field‐Induced Gradient Wetting for Controllable Liquid Transport: From Movement on the Surface to Penetration into the Surface

“…Che et al reported that CO 2 -responsive surface wettability to oil/water can be realized on nanostructured electrospun poly mer (PMMA-co-PDEAEMA) membranes, which show promise as an oil/water on-off switch for controlled oil/water separation. [165] The other way to achieve gas-responsive surfaces is based on annealing a membrane in a different atmosphere. When a ZnO-nanowire-coated mesh was annealed at 300 °C in an atmosphere of oxygen and hydrogen, its surface wettability could be switched between superhydrophilic and superhydrophobic for different types of oil-water separation (i.e., waterremoval and oil-removal modes, respectively).…”

Synthesis of porous polymer/tissue paper hybrid membranes for switchable oil/water separation

“…Therefore reversible switching of a surface state between being hydrophilic and hydrophobic is crucial, which can be achieved by engineering stimuli-responsive surfaces with well-designed nano- or microstructures. These external stimuli include electrical potential 13, 14 , temperature 15, 16 , light illumination 17, 18 , pH value 19, 20 , gas 21 , and solvent 22–25 . Using solvent to control the surface hydrophilicity/hydrophobicity is a simple and practical approach.…”