Cotton fabrics modified with tannic acid/1-eicosanamine grafting layer for oil/water separation

The wettability of the surface of hydrophilic cotton fabrics was modified using a one-step protocol with tannic acid (TA) to provide its excess catechol groups to be grafted with 1-eicosanamine at pH 8.5 and room temperature with catalysts CuSO4/H2O2. The modification over the synthesis conditions revised the contact angles of water and diiodomethane droplets from 132.68 ± 0.49° to 143.95 ± 0.80° and from 100.08°±1.42° to 82.96 ± 1.38°, respectively. The corresponding dispersive of the so-yielded cotton surface ranged from 8.6 to 16.0 mJ/m2, and the polar components ranged from 0.08 to 2.7 mJ/m2, much lower than polytetrafluoroethylene. The modified cotton fabrics are omniphobic and can repel water and commercial oil products. The absorption tests revealed that the modified cotton fabrics absorbed 1.10 g hexane/g cotton by contacting hexane (top)-water (bottom) layers and absorbed 1.26 g hexane/g cotton by contacting water first for 30 s, then hexane for another 30 s. The modified fabrics reveal good absorption reusability as hexane absorbent is even pre-saturated with water. This conclusion is also valid for commercial unleaded gasoline #95 and diesel. A parametric study revealed that the added catalysts and prolonged reaction time would enhance the hydrophobicity of the surface. These modified cotton fabrics can absorb oil from water and oil spills. Mechanisms corresponding to this observation are discussed.

Superhydrophobic Flexible Strain Sensors Constructed Using Nanomaterials: Their Fabrications and Sustainable Applications

Superhydrophobic flexible strain sensors, which combine superhydrophobic coatings with highly sensitive flexible sensors, significantly enhance sensor performance and expand applications in human motion monitoring. Superhydrophobic coatings provide water repellency, surface self-cleaning, anti-corrosion, and anti-fouling properties for the sensors. Additionally, they enhance equipment durability. At present, many studies on superhydrophobic flexible sensors are still in the early research stage; the wear resistance and stability of sensors are far from reaching the level of industrial application. This paper discusses fundamental theories such as the wetting mechanism, tunneling effect, and percolation theory of superhydrophobic flexible sensors. Additionally, it reviews commonly used construction materials and principles of these sensors. This paper discusses the common preparation methods for superhydrophobic flexible sensors and summarizes the advantages and disadvantages of each method to identify the most suitable approach. Additionally, this paper summarizes the wide-ranging applications of the superhydrophobic flexible sensor in medical health, human motion monitoring, anti-electromagnetic interference, and de-icing/anti-icing, offering insights into these fields.

New superhydrophobic and self-cleaning zirconia/polydimethylsiloxane nanocomposite coated cotton fabrics

Zirconia/polydimethylsiloxane nanocomposite coated fabric demonstrates unique stability with tendencies toward self-cleaning and oil–water separations due to its nanopatterned morphologies and adhering superhydrophobic polysiloxane chemical groups.

Robust Waterborne Superhydrophobic Coatings with Reinforced Composite Interfaces

Waterborne superhydrophobic coatings have attracted tremendous attention recently, but their practical applications are severely limited by hydrophobic instability and poor mechanical durability. Herein, a novel robust waterborne PTFE-CP&MgO-AOP superhydrophobic coating was successfully fabricated by reinforcing composite interfaces. Combined with the self-polymerization of dopamine and the in situ grown MgO, CNTs-polydopamine&MgO (CP&MgO) particles with improved interfacial compatibility were obtained. Through the cross-linking and hydrogen bonding interactions, phosphate networks (CP&MgO-AOP) with the aluminum orthophosphate (AOP) binder were formed during dehydration polymerization. The phosphate networks not only enhanced the interfacial interaction among CP&MgO to form coral-like structures but also strengthened the interfacial binding force between the waterborne polytetrafluoroethylene (PTFE) coating and the substrate. With the enhanced composite interfacial strength, the waterborne PTFE-CP&MgO-AOP coating exhibited excellent wear-resistance, which can withstand more than 1.27 × 10⁵ abrasion cycles. Moreover, the chemical bonding between the functional groups of phosphate networks and metal substrate improved the adhesion strength from grade 5 to 1. Furthermore, the prepared coating surface with the reticular/coral-like composite structures can lock the stable gas layer to maintain excellent hydrophobic stability, even under the conditions of strong acidic/alkaline, high-temperature, xenon lamp irradiation, and mechanical wear. Thus, this study is expected to open new insights into interfacial enhancement of robust waterborne superhydrophobic coatings.