Randomly heterogeneous oleophobic/pH-responsive polymer coatings with reversible wettability transition for multifunctional fabrics and controllable oil?water separation

Stimuli-responsive surfaces with wettability change between superhydrophilic and superhydrophobic are susceptible to oil contamination which often ruins the surface. Herein, a coating with pHswitchable wettability transition between superamphiphobic and superhydrophilic-superoleophobic is achieved by rationally designing oleophobic/pH-responsive polymer heterogeneous chemistry. Fabrics modified with this coating show repellency to both water and oils, while upon exposure to acidic water (pH = 1) the fabrics change to be superhydrophilic-superoleophobic within a short response time of <5 s. More importantly, the superamphiphobicity of the fabric can be restored under mild alkaline condition (pH = 10), and the transition is reversible for many cycles. The effective in situ or ex situ wettability change under acidic/alkaline water treatment makes the coated fabric capable of separating oil?water mixture or even some mixtures of immiscible organic solvents. In addition, the coated fabric is also demonstrated to be promising as a new class of functional fabrics that provide protection against water and many oils in one condition, and can change to be hygroscopic, anti-static, oil-repellent and anti-oil -fouling in the other condition for improved wear comfort and self-cleaning. (c) 2021 Elsevier Inc. All rights reserved.

Automated summary

A coating with pH-switchable wettability transition between superamphiphobic and superhydrophilic-superoleophobic has been achieved through rational design of oleophobic/pH-responsive polymer heterogeneous chemistry. The coated fabric shows repellency to water and oils, quickly transitioning to superhydrophilic-superoleophobic under acidic conditions and can be restored to superamphiphobic under mild alkaline conditions, with the transition being reversible for multiple cycles. The fabric can effectively separate oil-water mixtures and various immiscible organic solvent mixtures, and also offers other functionalities such as hygroscopicity, anti-static properties, oil-repellency, and anti-oil fouling for improved comfort and self-cleaning.