Ultra-thin, self-healing polymers create new durable, water-resistant coatings – sciencedaily

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Researchers have found a way to make ultra-thin surface coatings tough enough to resist scratches and dents. The new material, developed by merging thin film and self-healing technologies, has an almost endless list of potential applications, including self-cleaning, anti-frost, anti-fog, anti-bacterial, anti-fouling and anti-fouling coatings. improved heat exchange. , the researchers said.

The new study found that the rapid evaporation qualities of a specialized polymer containing a network of dynamic bonds in its backbone help form a water-resistant, self-healing coating of nanoscale thicknesses. The study, led by University of Illinois professor of mechanical science and engineering Urbana-Champaign Nenad Miljkovic and professor of materials science and engineering Christopher Evans, is published in the journal Nature Communication.

For this study, the main objective of the Miljkovic group was to increase the efficiency of steam power plants, which are the largest producers of electricity in the world, by using these types of coatings in their condensers. “The coatings, when applied to the surfaces of condensers, make them more water resistant and effective at forming water droplets, which optimizes heat transfer,” said the graduate research assistant Jingcheng Ma, co-lead author of the study.

When used in steam power plants, thin coatings can run into a host of durability issues, the researchers said. Coatings can break down in a matter of weeks, sometimes even hours. Such a short lifespan makes the application of coatings in the real world impractical, which has been a fundamental challenge in mechanical and materials science for about eight decades. Thicker coatings may be more durable, but they reduce heat transfer and erode the associated benefits of the coating.

Previous studies have shown that most ultrathin coatings develop tiny pinhole defects once they harden on a surface. Steam penetrates through these defects, causing the coating to gradually delaminate, the researchers said. Their goal was therefore to develop a thin film without pinholes and water resistance and improve the overall energy efficiency of steam plants by several percent.

“Self-healing materials can recycle and reprocess themselves,” Evans said. “We have found that we can successfully use the healing provided by dynamic bonds, allowing coatings to self-repair in response to scratches or prevent the growth of pinholes.”

Called dyn-PDMS, the material can be easily applied by immersion on materials in nanoscale layers on various surfaces like silicon, aluminum, copper or steel.

“One of the reasons we can get such thin layers is that the solvents used in the reaction evaporate very quickly, leaving only the polymer,” Evans said. “Also, once cured, the material repairs itself from scratches very quickly – so quickly that it is difficult to observe in real time. We don’t see this behavior in large, loose samples of the material – only in the thin film. , and that’s a question we’re trying to answer now. “

The researchers postulate that the ultra-thin coatings developed in this study provide a solution for durable water-resistant materials and raise open scientific questions within materials science and fluid mechanics that remain unanswered.

The Office of Naval Research, the International Institute for Carbon Neutral Energy Research, the Air Force Office of Scientific Research and the National Science Foundation have supported this research.

Both Miljkovic and Evans are affiliated with the Materials Research Laboratory. Miljkovic is also affiliated with Electrical and Computer Engineering. Evans is also affiliated with the Beckman Institute for Advanced Science and Technology and Chemical and Biomolecular Engineering.


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