Krytox

Krytox is a registered trademark of The Chemours Company. It refers to a group of colourless synthetic lubricants (oils and greases) with a variety of applications.[1] Invented by researchers at DuPont, Krytox oils are fluorocarbon ether polymers of polyhexafluoropropylene oxide, with a chemical formula: F−(CF(CF3)−CF2−O)n−CF2CF3, where the degree of polymerization, n, generally lies within the range of 10 to 60.[2] These compounds are collectively known by many names including perfluoropolyether (PFPE), perfluoroalkylether (PFAE) and perfluoropolyalkylether (PFPAE). A unique identifier is their CAS registry number, 60164-51-4.

Krytox fluoroether-based grease pictured alongside a tube of Dow Corning silicone grease (green). Both are often used in laboratories, including in high-vacuum applications, due to their inertness.

In addition to PFPE, Krytox grease also contains telomers of PTFE and in fact was designed as a liquid or grease form of PTFE. It is thermally stable, nonflammable (even in liquid oxygen), and insoluble in water, acids, bases, and most organic solvents. It is nonvolatile and useful over a broad temperature range of −75 to 350 °C (−100 to 660 °F) or higher. Its high resistance to ionizing radiation makes it useful for the aerospace and nuclear industries. Formulations exist which are able to withstand extreme pressure, resist outgassing in high vacuum, and operate under intense mechanical stress.[3]

Other companies manufacture PFPE lubricants, such as Solvay's Fomblin range,[4] with some formulations having comparable properties.[5]

Safety

The manufacturer states on Krytox tubes, "May cause mild skin and eye irritation. Contact with very hot surfaces (above 500°F/260°C) can generate fumes which can cause coughing or respiratory irritation. Large amounts could lead to lung damage which might not be apparent for several hours. These fumes may also cause flu-like symptoms."[6][7]

References
  1. Günter Siegemund, Werner Schwertfeger, Andrew Feiring, Bruce Smart, Fred Behr, Herward Vogel, Blaine McKusick “Fluorine Compounds, Organic” Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2002. doi:10.1002/14356007.a11_349
  2. DuPont Krytox Performance Lubricants Product Overview, available online here
  3. "Krytox Application Overview". Miller-Stephenson. Retrieved 2017-06-30.
  4. "Fomblin® PFPE Lubricants". Solvay. Retrieved 2017-06-30.
  5. "Krytox® Competitive Product Comparison" (PDF). DuPont. Retrieved 2017-06-30.
  6. "Krytox® PFPE/PTFE Greases (GPL 20(X) Series) Material Safety Data Sheet" (PDF). Dupont. Retrieved 15 June 2013.
  7. "Krytox® PFPE Oils Material Safety Data Sheet" (PDF). DuPont. Retrieved 15 June 2013.
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