Bio‐Inspired Design and Fabrication of Micro/Nano‐Brush Dual Structural Surfaces for Switchable Oil Adhesion and Antifouling

Abstract

The underwater superoleophobic surfaces play a significant role in anti-oil contamination, marine antifouling, etc. Inspired by the Gecko's feet and its self-cleaning property, a hierarchical structure composed of poly (acrylic acid) gel micro-brushes is designed by the liquid-infused method. This surface exhibits underwater superoleophobicity with very low oil adhesion. It is then modified with stimuli-responsive polymer nano-brushes via surface-initiated atom transfer radical polymerization from the embedded initiator. The micro/nano-brush dual structural surfaces can switch the underwater oil adhesion between low and high while keeping the superoleophobicity. The antifouling properties against algae attachment under different mediums are also investigated to show a strong link between oleophobicity and antibiofouling property. The model surface will be very useful in directing the design of marine self-cleaning coatings to both living and non-living species.

NIR‐Triggered Photothermal Responsive Coatings with Remote and Localized Tunable Underwater Oil Adhesion

“…Below the lower critical solution temperature (LCST, ≈32 °C), the intermolecular hydrogen can occur between NH functional groups of PNIPAm and water molecules, which provides the coating surface with high ration of water content and hydrophilic feature to form the “lotus” state contacting with superoleophobicity and low oil adhesion between oil droplets and coating surface. On the contrary, when the temperature is higher than LCST, C  O and NH functional groups can form intramolecular hydrogen, PNIPAm would be dehydrated and in a hydrophobic state, to generate the strong interaction between the coating surface and oil droplet, which is similar to the underwater Wenzel's state with superoleophobicity and high oil adhesion . The adhesion forces between the oil droplet and the coating surface were measured through a high‐sensitivity micro electromechanical balance system (Figure d).…”

A Bioinspired Hierarchical Underwater Superoleophobic Surface with Reversible pH Response

“…Superoleophobic surfaces display large contact angles (greater than 150°) against organic liquids in aqueous environment are most widely studied in the past decades because of their excellent oil‐repellent ability. [ 1–3 ] Such artificial materials have gained more attention recently attributed to their potential applications in the field of droplet manipulation in microfluidics, [ 4 ] antioil contamination, [ 5 ] resistance reduction of oil transportation, [ 6 ] anti‐biofouling, [ 7 ] industrial metal cleaning, [ 8 ] and oil/water separation. [ 9 ] In order to obtain surfaces with more sophisticated oil‐repellent abilities, further development and exploration of new materials and ingenious fabrication methods is necessary.…”

“…This seemingly contradictory proposal can be realized with the aid of stimuli responsive materials. Presently, multifunctional superoleophobic surfaces with tunable oil adhesion under external stimulus via photoirradiation, [ 18 ] thermal, [ 19 ] pH, [ 20 ] electric field, [ 21 ] magnetic field [ 22 ] treatment, and multistimulus combinations, [ 23 ] have been discovered by means of electrochemical deposition, [ 24 ] laser ablation, [ 25 ] self‐assembly, [ 26 ] chemical etching, [ 27 ] spray/dip coating, [ 1 ] the template method, [ 28 ] lithography, [ 29 ] electrochemical anodization, [ 30 ] and the hydrothermal method [ 31 ] among others. [ 13 ]…”

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

“…[108][109][110][111][112][113][114][115][116] Jiang's group have made a large contribution to this field. [108][109][110] Water-droplet adhesion switching has been achieved by the thermoresponsive phase transition of the n-paraffin-swollen organogel surface for water-droplet movement control.…”