March 9th, 2022
Researchers in China have reportedly developed a new superhydrophobic coating that provides several beneficial properties, including the ability to self-clean and prevent corrosion.
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 conducted by 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 has since been published in Chemical Engineering JournalChemical Engineering Journal.
Coating Research
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.
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.
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.
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.
Other Nature-Inspired Coatings
Researchers at the University of Toronto announced they are looking at the adhesion of mussels on surfaces to potentially create new antifouling coatings for infrastructure and medical adhesives. The study, led by Professor Eli Sone, was published in Scientific Reports.
The research team has reportedly been studying zebra and quagga mussels for years at the university’s material science and engineering research lab. These species are native to lakes and rivers in southern Russia and Ukraine, and likely made their way to the Great Lakes in North America in the 80s on ships from Europe.
Since these mussel species can be invasive and cause problems, like displacing native mussel species and fouling boats, water intake pipes and other infrastructure, the team decided to look at new techniques for measuring adhesion of zebra and quagga mussels to various surfaces to develop effective antifouling surfaces.
The team utilized a pair of fine-tipped, self-closing tweezers, a digital camera and a force gauge to measure how much force was required to break the protein-based glue secreted by the mussels. The mussels were collected from the wild and placed on glass, PVC and PDMS substrates to reattach.
Quagga mussels reportedly showed a significantly lower attachment rate on PDMS compared to glass and PVC, while the zebra mussels showed a consistent attachment rate across all three substrates.
Research found that overall the mussels adhered more strongly to glass than they did to plastics. According to the University of Toronto, researchers expected this since glass is inorganic and hydrophilic, similar to the rocks that the mussels use as substrates in nature, while PDMS repels water and is often coated on boat hulls to prevent biofouling.
