Polytetrafluoroethylene synthesis reaction

Decomposition can be looked upon as the reverse reaction of synthesis. Polymers with a ceiling temperature can simply show a reverse of the polymerization reaction as seen in Fig. 3.30. Figure 3.49 represents typical thermogravimetry traces for the decomposition of poly(methyl methacrylate), PMMA, and polytetrafluoroethylene,... 

In precipitation polymerization, the reaction mixture is initially homogeneous, as in solution polymerization, but it is a precipitant for the polymer. Thus, the initially formed macromolecules collapse and coagulate to create particle nuclei, which gradually flocculate into irregularly shaped and polydisperse particles. Such a process concerns for instance the synthesis of polytetrafluoroethylene in water or polyacrylonitrile in bulk. 

CF) is prepared by the reaction of carbon powder with fluorine gas at an elevated temperature. The properties of (CF) are similar to those of polytetrafluoroethylene (PTFE) which is prepared by organic synthesis. 

As a result of the increased uptake of pharmaceutical compounds containing fluorine substituents, efficient synthetic methods are sought for the introduction of fluorine into small organic compounds. A recent example reported by Gustafsson et al. demonstrated the synthesis of fluori-nated alcohols, aldehydes, and carboxylic acids using dieth-ylamino sulfur 6 (DAST) in a polytetrafluoroethylene (PTFE) tube reactor. Employing a reaction time of 16 minutes and a temperature of 70°C (at 5 bar pressure), the authors were able to isolate the fluorinated compound in yields ranging from 40% to 100% (Scheme 6.3). 

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