Smudge-proof, bendable coating resists scratches

Keys and dust particles can easily scratch up smartphone screens. But a new coating could make such abrasive actions inconsequential. Chemists in Guojun Liu’s lab at Queen’s University in Ontario have created a transparent composite coating that remains scratch-free when it is scraped with steel wool 20 times (Angew. Chem., Int. Ed. 2019, DOI: 10.1002/anie.201904210). When cast on a plastic film, the material also bends up to 500 times without apparent damage and resists smudges. Liu’s team created the coating by cross-linking octa(3-glycidyloxypropyl) polyhedral oliogomeric silsesquioxanes (GPOSS) via ring-opening polymerization of GPOSS’s epoxides. GPOSS’s silica core gives the material its hardness; the glycidyloxypropyl network bestows flexibility. The chemists also incorporated poly(dimethylsiloxane) into the composite. This low-surface-tension liquid lubricant makes the coating omniphobic, meaning it repels both oil- and water-based contaminants. Liu says this is the first material that’s wear resistant, flexible, transparent, and omniphobic. Plus, he says, it’s easy to make. Liu says that in addition to potentially being a protective coating for displays, the composite could be used for automobile bodies and windshields, if it doesn’t degrade when exposed to sunlight for extended periods.