Properties
The combination of the stable Teflon backbone with the acidic sulfonic groups gives Nafion its characteristics:
- It is highly conductive to cations, making it suitable for many membrane applications.
- It resists chemical attack. According to DuPont, only alkali metals (particularly sodium) can degrade Nafion under normal temperatures and pressures.
- The Teflon backbone interlaced with the ionic sulfonate groups gives Nafion a high operating temperature, e.g. up to 190 °C, however, in membrane form, this is not possible due to the loss of water and mechanical strength.
- It is a superacid catalyst. The combination of fluorinated backbone, sulfonic acid groups, and the stabilizing effect of the polymer matrix make Nafion a very strong acid, with pKa ~ -6. In this respect Nafion resembles the trifluoromethanesulfonic acid, CF3SO3H, although Nafion is a weaker acid by at least three orders of magnitude.
- It is selectively and highly permeable to water.
Read more about this topic: Nafion
Famous quotes containing the word properties:
“The reason why men enter into society, is the preservation of their property; and the end why they choose and authorize a legislative, is, that there may be laws made, and rules set, as guards and fences to the properties of all the members of the society: to limit the power, and moderate the dominion, of every part and member of the society.”
—John Locke (1632–1704)
“A drop of water has the properties of the sea, but cannot exhibit a storm. There is beauty of a concert, as well as of a flute; strength of a host, as well as of a hero.”
—Ralph Waldo Emerson (1803–1882)