November_December_2021_AMP_Digital

A D V A N C E D M A T E R I A L S & P R O C E S S E S | N O V E M B E R / D E C E M B E R 2 0 2 1 1 4 SURFACE ENGINEERING VERSATILE SELF-HEALING COATINGS Researchers from the University of Illinois Urbana-Champaign developed a tougher ultrathin material by merging thin-film and self-healing technologies. They found that the rapid evaporative qualities of a specialized polymer con- taining a network of dynamic bonds in its backbone help form a water-resis- tant, self-healing coating of nanoscale thicknesses. The new material has an expansive list of potential applications, including self-cleaning, anti-icing, anti- fogging, anti-bacterial, anti-fouling, and enhanced heat exchange coatings, ac- cording to the researchers. The research team’s primary focus was increasing the efficiency of steam power plants—the biggest producers of electricity globally—by using these types of coatings in their condensers. “The coatings, when applied to the sur- faces of the condensers, make them more water-resistant and efficient at forming water droplets, which optimi- zes heat transfer,” explain the researchers. Previous studies have shown that most ultrathin coatings develop tiny pinhole defects once they cure onto a surface. Steam penetrates through these defects, leading to the gradual de- lamination of the coating, the research- ers say, so their goal was to develop a pinhole-free, water-resistant thin-film and enhance the overall energy effi- ciency of steam power plants by several percent. “Self-healing materials can recycle and reprocess themselves,” says one of the study’s lead researchers, Chris- topher Evans. “We found that we can successfully utilize the healing enabled by the dynamic bonds, allowing the coatings to self-repair in response to scratching or to prevent pinholes from growing.” The material can be easily dip-coated onto materials in nanoscale layers on various surfaces like silicon, aluminum, copper, or steel. illinois.edu . COMPARING ULTRASLIPPERY SURFACES A research team from the Chinese Academy of Sciences systematically com- pared superhydrophobic and liquid- infused slippery surfaces with special wettability. The intrinsic hydrophilic- ity, liquid adhesion, surface contami- nation, corrosion attack, and ice- over phenomena of metallic materi- als greatly restrict their wide utiliza- tions. Given the unique interfacial phase contacts and water repellency properties, lotus-leaf inspired super- hydrophobic surfaces and pitcher-plant inspired liquid-infused slippery surfac- es are promising candidates for multi- functional applications. The team set out to determine which surface is better performing. The researchers prepared super- hydrophobic and lubricant-infused ul- traslippery surfaces through chemical etching, low surface energy molecule grafting, and lubricant oil infusion. Then they compared the surface wettability, self-cleaning, anti-icing, anticorrosion behaviors, and mechanical durability to study the functional differences and mechanisms. They found that both su- perhydrophobic and lubricant-infused surfaces exhibited self-cleaning ability, ice-over delay effect, marked decrease in the ice adhesion strength, and distinct increase in charge-transfer resistance. “Most notably,” the researchers say, “given the existence of a stable, defect-free, and inert lubricant-infused layer, the lubricant-infused ultraslip- pery surfaces possess superior me- chanical robustness against abrasion or knife scratching damage and bet- ter long-term corrosion resistance.” english.cas.cn. BRIEF University of Cambridge, the Icahn School of Medicine at Mount Sinai, ResInnova Labs, and Ascend Performance Materials discovered that a nylon fabric embedded with zinc ions successfully inactivated 99%of the viruses that cause COVID-19 and the common flu. The findings could lead to more effective advanced personal protective equipment. ascendmaterials.com . A new type of water-resistant coating is also sustainable. Courtesy of CC0 Public Domain. Liquid-infused slippery surfaces are less prone to corrode over time. Courtesy of Langmuir.