Preparation
Nafion derivatives are first synthesized by the copolymerization of tetrafluoroethylene (TFE) (the monomer in Teflon) and a derivative of a perfluoro (alkyl vinyl ether) with sulfonyl acid fluoride. The latter reagent can be prepared by the pyrolysis of its respective oxide or carboxylic acid to give the olefinated structure.
The resulting product is an -SO2F-containing thermoplastic that is extruded into films. Hot aqueous NaOH converts these sulfonyl fluoride (-SO2F) groups into sulfonate groups (-SO3-Na+). This form of Nafion, referred to as the neutral or salt form, is finally converted to the acid form containing the sulfonic acid (-SO3H) groups. Nafion can be cast into thin films by heating in aqueous alcohol at 250 °C in an autoclave. By this process, Nafion can be used to generate composite films, coat electrodes, or repair damaged membranes.
Read more about this topic: Nafion
Famous quotes containing the word preparation:
“With memory set smarting like a reopened wound, a man’s past is not simply a dead history, an outworn preparation of the present: it is not a repented error shaken loose from the life: it is a still quivering part of himself, bringing shudders and bitter flavours and the tinglings of a merited shame.”
—George Eliot [Mary Ann (or Marian)
“Living each day as a preparation for the next is an exciting way to live. Looking forward to something is much more fun than looking back at something—and much more constructive. If we can prepare ourselves so that we never have to think, “Oh, if I had only known, if I had only been ready,” our lives can really be the great adventure we so passionately want them to be.”
—Hortense Odlum (1892–?)
“It’s sad but true that if you focus your attention on housework and meal preparation and diapers, raising children does start to look like drudgery pretty quickly. On the other hand, if you see yourself as nothing less than your child’s nurturer, role model, teacher, spiritual guide, and mentor, your days take on a very different cast.”
—Joyce Maynard (20th century)