Robust Thermoresponsive Polymer Composite Membrane with Switchable Superhydrophilicity and Superhydrophobicity for Efficient Oil–Water Separation

Abstract

Herein, we report for the first time on the fabrication of a robust, thermoresponsive polymer membrane produced by the combination of an elastic polyurethane (TPU) microfiber web and poly(N-isopropylacrylamide) (PNIPAM). PNIPAM hydrogel is evenly coated on the surface of TPU microfibers, and thus, the wettability of TPU-PNIPAM membrane is amplified by taking advantage of the hierarchical structure and increased surface roughness. The TPU-PNIPAM membrane possesses switchable superhydrophilicity and superhydrophobicity as the temperature of membrane changes from 25 to 45 °C. The composite membrane is shown successfully able to separate a 1 wt % oil-in-water emulsion and 1 wt % water-in-oil emulsion at 25 and 45 °C, respectively, with a high separation efficiency of ≥99.26%. Furthermore, the composite membranes show excellent mechanical properties, and they are highly flexible and mechanically tough. The smart composite membranes reported here have shown great potential for further development for practical high-efficiency oil-water separations.

Recent Progress of Polyurethane-Based Materials for Oil/Water Separation

“…With advantages of low cost and high e±ciency, centrifugal spinning technology has been developed from the initial preparing arti¯cial hair to the recent fabricating nano¯ber membranes. 55,56 Ou et al 57 reported for the¯rst time on the fabrication of a robust, thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) hydrogel-coated PU membrane by centrifugal spinning for e®ective separation of oil/water emulsions. The reason of selecting thermoplastic PU was its high tensile strength, wear resistance and good°exibility over a wide temperature range.…”

Rotary jet spinning review – a potential high yield future for polymer nanofibers

“…By using this process, one could produce an efficient layer of an organic solar cell. 135 Further potential applications being studied include supercapacitors based on flexible graphene/polyaniline nanofiber composite films [136], graphene/polyaniline nanofiber composites as supercapacitor electrodes, 137 lithium-ion battery separators from PAN, 77,138 polystyrene (PS) nonwoven fabrics featuring radiation induced color changes, 139 nanofiber hydrophilic studies 70,140,141 and anionic dye adsorption techniques [142] to name but a few.…”

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

“…[154] Other thermoresponsive membrane composites containing PNIPAAm have also been used to efficiently separate oil-water mixtures and even oil-in-water and W/O emulsions. [155,156] In addition, thermoresponsive melamine sponges containing PNIPAAm can effectively absorb and release oil under water with alternative high and low temperature, respectively, which has potential for smart oil/water separation. [157] …”