[A new cellulose material that collects water droplets from fog]
Release date:[2022/8/10] Read a total of[54]time

Cellulose is the oldest and most abundant natural polymer on earth. It is a kind of renewable material with strong hygroscopicity, and the abundant hydroxyl group on its molecular skeleton provides efficient hydrophilic water for fog collection. However, continuous hydrophilic waters lead to the pinning of nucleating droplets on the surface and interfacial shielding of the condensed water film.

Taking inspiration from cactus spines and beetle wings, the Guangxi University research team created a new cellulose material that can collect water droplets from fog. By selectively regulating the polar and dispersive components of the surface free energy of cellulose, discontinuous molecular hydrophilic/hydrophobic regions are achieved. Then it was coated on the surface of asymmetric spines, and a double biomimetic surface which could realize the rapid nucleation and removal of droplets was simply constructed. It is worth noting that the spontaneous interfacial charge interaction between the droplet and the collector was developed and utilized for the first time, and the water collection efficiency reached 93.18 kg/ (m2·h).


Design of asymmetric amphiphilic surfaces based on cellulose

Prickly pear cactus is one of the few plants suitable for growing in extremely arid areas. In addition to avoiding evaporation and loss of water by reducing leaves to needles, its needles also have the function of actively collecting fog to provide external water supplement. In addition, the Naboo desert beetle can also get water from thin air. Hydrophilic - hydrophobic pattern through dorsal elytra surface. The hydrophilic region captures the water mist, and the droplets condense and increase and then transfer to the hydrophobic region. The low surface energy of the hydrophobic region enables the rapid removal of large droplets from the Elytra surface. Inspired by the delicate structures and ingenious mechanisms of the two creatures, the researchers designed a dual biomimetic water mist collection surface.


Characterization of asymmetric amphiphilic materials based on cellulose

An amphiphilic cellulose ester coating was prepared by nucleophilic substitution of 10-undecenoyl chloride with hydrophobicity. The physical and chemical properties of cellulose esters were investigated by elemental analysis, solid state 13C NMR spectrometer, Fourier transform infrared spectrometer and X-ray electron spectroscopy.


Surface wetness and durability

Surface wettability plays an important role in droplet nucleation and removal. Contact Angle, contact Angle hysteresis, surface free energy and interfacial tension were evaluated by contact Angle measuring instrument.


Static electricity assisted water collection

Almost all known materials have contact-electric effect, and charge transfer occurs when water droplets and polymers are separated by contact. This study revealed for the first time the electrostatic adsorption phenomenon between the water collection surface and the fog droplets, and it was used to assist in enhancing water collection. The final water collection efficiency is as high as 93.18 kg/ (m2·h), which is higher than the fog collectors of the currently known biomimetic beetles and cacti.


It is reported, The results were published in Nature under the title "Bioinspired asymmetric Amphiphilic Surface for Triboelectric Enhanced Efficient Water Harvesting. Communications.


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