An Antismudge Coating Free Of Fluorine

To keep windows and walls free of stray marks and fingerprints, people often turn to antismudge coatings that are capable of repelling both water and oil. To date, however, most of these coatings have used fluorine-based chemicals to achieve their dual oleophobic and hydrophobic properties. Such chemicals can be expensive, and because they are extremely stable, they have been shown to accumulate in the environment. Seeking to prevent smudges without using fluorine-based materials, Muhammad Rabnawaz, Guojun Liu, and Heng Hu of Queen’s University, in Ontario, wondered if they could capitalize on reports that monolayers of poly(dimethylsiloxane), or PDMS, can repel both water and oily compounds. Not only is PDMS inexpensive, they reasoned, it is considered nontoxic and has been used in medical implants. The researchers created a clear polyurethane coating containing PDMS (Angew. Chem. Int. Ed. 2015, DOI: 10.1002/anie.201504892). Thanks to PDMS chains on its surface, the coating repels ink, paint, and fingerprints when applied to glass. Because the coating retains its properties even after extensive wear, the researchers suggest it would be useful for preventing smudges on handheld electronic devices, such as smartphones.