Superhydrophobic pillar arrays, which can generate the droplet pancake bouncing phenomenon with reduced liquid-solid contact time, have huge application prospects in anti-icing of aircraft wings from freezing rain. However, the previously reported pillar arrays, suitable for obtaining pancake bouncing, have a diameter ≤100 μm and height-diameter ratio >10, which are difficult to fabricate over a large area. Here, we have systematically studied the influence of the dimension of the superhydrophobic pillar arrays on the bouncing dynamics of water droplets. We show that the typical pancake bouncing with 57.8% reduction in contact time with the surface was observed on the superhydrophobic pillar arrays with 1.05 mm diameter, 0.8 mm height, and 0.25 mm space. Such pillar arrays with millimeter diameter and <1 height-diameter ratio can be easily fabricated over large areas. Further, a simple replication-spraying method was developed for the large-area fabrication of the superhydrophobic pillar arrays to induce pancake bouncing. No sacrificial layer was needed to reduce the adhesion in the replication processes. Since the bouncing dynamics were rather sensitive to the space between the pillars, a method to control the contact time, bouncing shape, horizontal bouncing direction, and reversible switch between pancake bouncing and conventional bouncing was realized by adjusting the inclination angle of the shape memory polymer pillars.
Superhydrophobic conical pillars have great industrial application potential in, for example, anti-icing of aircraft wings and protecting high voltage transmission lines from freezing rain because of their droplet pancake bouncing phenomenon which is recognized to furthest reduce the liquidsolid contact time. However, there are still no methods that can large-scale fabricate robust
Superhydrophobic
filtrating materials have been widely developed
for rapid removal or collection of oils from oil/water mixture due
to the increasing water pollution caused by oil spills and oil-contaminated
wastewater. However, poor reusability, superhydrophobic failure in
harsh environments, and that only heavy oil or light oil was separated
from water seriously restricted their practical application. Herein,
superhydrophobic carbon fibers were first fabricated using a novel
nickel electroplating for versatile oil/water separation with excellent
reusability and high environmental stability. The interconnected nanometer-scale
nickel grains formed on the micrometer-scale fibers and fluoroalkylsilane
molecules enabled the fibers to be superhydrophobic with the water
contact angle (CA) of ∼159.1° and superoleophilic with
the oil CA of ∼0°. The nickel coating contributed to the
improvement of the bonding strength, tensile strength, and oxidation
resistance of the fibers. The as-prepared fibers could be applied
for the separation of heavy or light oil/water mixtures with separation
efficiencies above 99.1%, during which the oil content in the separated
water all remained below 78 ppm. The fibers also realized the highly
efficient separation of dichloromethane and various harsh environmental
solutions such as hot water, acid, alkali, and salt. The superhydrophobicity
of the fluorinated nickel-coated carbon fibers still remained even
after 100 cycles of separation and 24 months of storage in air, demonstrating
outstanding durability of the fibers. These novel superhydrophobic
carbon fibers had promising potentials for versatile oil/water separation
in practical applications.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.