Kingston, Ontario – Self-cleaning windows and graffiti-proof walls are two applications mooted by a Queen’s University researchers for fluorine-free anti-smudge polyurethane coatings.
The scientists introduced a new method for producing a transparent polyurethane, smudge-resistant coating that is resistant to both water and oil-soluble contaminants. Its details were published in the journal Angewandte Chemie in September, 2015.
According to the study: “The success of this new coating stems from grafted side chains made of poly(dimethylsiloxane) (PDMS), a biocompatible silicone oil used in medicine.
“The individual components and the conditions for the synthesis were chosen to produce a highly cross-linked polyurethane matrix in which nanodomains of PDMS are embedded.
“At the surface, the silicone side chains form a thin lubricating liquid film. When another liquid such as cooking oil is dispensed on the surface, the liquid readily slips off because the lubricating thin liquid film, unlike a solid surface, cannot grab the liquid,” the study said.
The new coatings repel ink, artificial fingerprints, and paint. They maintain their anti-smudge properties after being scratched with sandpaper. The researchers attribute this resiliency to the fact that after damage occurs, fresh PDMS side chains rise out of the nanodomains to the new surface, regenerating the damaged PDMS layer.
Smartphone touchscreens are another potential application according to the team’s head, Guojun Liu, a research professor at Queens University