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Researchers Develop New Superhydrophobic Coating

THURSDAY, OCTOBER 27, 2022


A research team from the Institute of Oceanology of the Chinese Academy of Sciences recently reported a new mechanical robust superhydrophobic coating that can be applied via spray-coating.

The study, published this month in the journal Materials & Design, was led by IOCAS Professors Hou Baorong and Duan Jizhou.

About the Coating

According to the institute’s release, lotus-inspired superhydrophobicity attracts researchers due to interfacial non-wetting and unique multi-phase contact properties. However, properties such as fragile hierarchical structures, fluorine-containing chemical usage and strict requirements for substrate scopes can provide challenges.

As a result, the research team developed the superhydrophobic coating (ZnO@STA@PDMS) with fluorine-free reagents. Additionally, the coating utilizes hierarchical rough micro-scale bump-porous structure, nano-scale particles and extremely low surface energy to repel water.

After spray-coated with the fabricated superhydrophobic coating, Q235 carbon steel’s ICorr saw decreases two orders of magnitude, suggesting a “superior” corrosion resistant performance. The |Z|10mHz value of the superhydrophobic coating is reportedly three orders of magnitude higher than the substrate.

Researchers utilized simulated marine atmospheric conditions with high relative humidity to test the coating, recording hygroscopic and deliquescence behaviors of NaCl salt particles. The results revealed that the corrosion damage in the edge of a saline droplet on bare Q235 carbon steel was more severe than interior because of faster ions transfer and abundant oxygen.

Based on this, researchers noted that the superhydrophobic coating possessed “promising” atmospheric corrosion inhibition performance based on the salt-deliquesce and instantaneous self-coalescence phenomenon observed.

The institute reports that the low interfacial adhesion force, low surface energy and air cushion-induced Cassie multi-phase contacts contributed to the saline droplet anti-wetting and remarkable anti-corrosion capability.

“This phenomenon provides a new type of anti-corrosion mechanism for superhydrophobic materials served in marine atmospheric environment with high relative humidity,” said Associate Professor Zhang Binbin, first and corresponding author of the study.

The research was supported by the Shandong Provincial Natural Science Foundation and the Youth Innovation Promotion Association of Chinese Academy of Sciences.

Other Superhydrophobic Coating Research

In February, researchers from the College of Chemistry and Chemical Engineering at Northeast Petroleum University and the School of Chemical Engineering and Technology and State Key Laboratory for Chemical Engineering at Tianjin University reportedly developed a new superhydrophobic coating that provides several beneficial properties, including the ability to self-clean and prevent corrosion.

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Inspired by Calliteara pudibunda, a highly elastic type of bristle worm, the polyphenylene sulfide (PSS) composite coating is created by combining expandable graphite and elastic fluororubber. The research was published in Chemical Engineering Journal.

Wanting to create a superhydrophobic coating that would adhere to rough structures and provide chemical durability, the research team synthesized hydrophobic nanoparticles using the sol-gel method with modified perfluorodecyltrichlorosilane (PFTS). These particles could reportedly expand to create micro- and nanostructures for superhydrophobicity during the treatment, with a water contact angle of 154±1.2 degrees and sliding angle of 3±0.5 degrees.

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Additionally, this combination created repairable microstructures that allow the coating to self-heal. The fluororubber resin acts as an elastic micro-support, to increase the coating’s resistance to bear and repair mechanical damage.

The thermal expansion and compression of the coating can uphold its superhydrophobicity and repair its damaged nanostructures even after 2,000 abrasion cycles under 125 kPa, exhibiting “fantastic” mechanical durability.

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Scientists report that the coating possessed strong anticorrosion and anti-scaling properties in a high salinity oil and water emulsion, due to the oleophilicty of the compound. This reportedly transforms the surface shielding layer from fragile air fil to stable oil firm to “impede scaling and corrosion mediums.”

To test its chemical durability, scientists immersed the coating in a strong acid and alkaline solution for seven days. It showed “exceptional” durability in this scenario, however, scientists reported that it is more suitable for acidic environments in practical applications.

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The coating is noted to be suited for outdoor application, as it demonstrated “outstanding” self-cleaning and anti-fouling properties to prevent surface contamination. Researchers say they expect to “open a new avenue to realize the large-scale applications of superhydrophobic coatings in harsh environments” with the development of their coating.

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Tagged categories: Carbon Steel; Coating Materials; Coatings; Coatings technology; Coatings Technology; Colleges and Universities; Corrosion; Corrosion protection; hydrophobic coatings; Program/Project Management; Research and development


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