The Interactions of n-C₅F₁₂ (a Model Compound to Partially Represent P.T.F.E.) on a Clean Iron Film

Abstract

As an initial exploratory experiment dodecafluoro n-pentane was chosen as a model compound for P.T.F.E. to simulate part of the perfluorinated molecular chain and allowed to adsorb at 0.13 μPa pressure and ambient temperature on a freshly prepared iron film produced by an evaporation process in situ from an iron wire wrapped around a tungsten filament. The events inside the vacuum chamber were followed with an MS 10 mass spectrometer and (where appropriate) a Pirani gauge. These experiments suggest that the ‘clean iron’ acts as a catalyst for the breakdown of the perf1uorinated alkane producing a variety of transiently reactive fragments, such as CF₂, that in turn may react with the borosilicate (Pyrex) glass walls of the reaction chamber. Generally speaking, perfluorinated compounds of the type used are exceptionally stable and do not break down except under extreme conditions (such as reaction with chlorine at 1073k) and so any apparent degradation products at such a low temperature are particularly interesting, especially since no mechanical shearing was involved.