The comparison of thermal stability of some hydrofluoroethers and hydrofluoropolyethers

The thermal stability of representative hydrofluoropolyether (HFPE) and hydrofluoroether (HFE) compounds has been evaluated. The observed stability order appears to be correlated with the nature of the hydrogenated chain ends; in particular, molecules having fully hydrogenated chain ends (OCH3 and OC2H5) show a significantly lower stability compared with the OCF2H terminated compounds. The main degradation products suggest, however, that the same primary reaction is responsible for the decomposition of all the compounds examined; this reaction involves the fragmentation of the RfOCxHyFz bond with fluorine transfer between the two carbon atoms close to the oxygen, leading to the formation of a hydrofluorocarbon CxHyF(z+1) and an acyl fluoride or a ketone.