Thermal Stability of Z-Type Perfluoro Poly Ether Lubricant Polymers: A Combined Thermogravimetric and Temperature Programmed Desorption Study

The thermal stability of Zdol 4000, 7800 and Ztetraol perfluoropolyethers (PFPE) have been studied in both the bulk with thermogravimetric analysis (TGA) and in thin film form with temperature programmed desorption spectroscopy (TPD). The TGA results have been interpreted to yield an evaporation activation energy for both Zdol 4000 (13 kcal/mole) and Zdol 7800 (19 kcal/mole). A larger activation energy is also found for all three samples investigated that is consistent with polymer decomposition (22, 27 and 21 kcal/mole respectively). The TPD threshold has been found to be approximately similar all three samples (∼500 K). The temperature of decomposition was also found to be similar for all three samples and was dominated by the CF₂O⁺ mass fragment at ∼660 K. Two desorption maximums were observed for both Zdol 4000 and Ztetraol indicating the similarity in their decomposition chemistry. In contrast only one desorption peak was observed from Zdol 7800 (675 K). A CF₃⁺ fragment was not observed in any of the TPD spectra indicating the absence an acidic decomposition path for all of the Fomblin Z polymers studied.