Low temperature oxidation of hexafluoropropene (HFP) by oxygen. Effects of kinetic parameters on the molecular mass of perfluoropolyethers

Abstract We have studied the low temperature fluorine initiated PFE synthesis from HFP and oxygen base, and determined the effects of parameters on molecular mass of the polymer obtained. As a result of kinetic analysis, the following expression for the degree of PFE polymerization is obtained: where p = degree of PFE polymerization; [M] = HFP concentration; W f =initiation rate; K 1 –K 6 =reaction rate constants of the elementary steps: 1. RO·+M ROM· 2. 2RO 2 · 2RO·+O 2 3. RO· R·′+A 4. 2RO 2 · ROOR+O 2 5. ROCF 2 CF(CF 3 )O· ROCF 2 CFO+CF 3 · 6. 2ROCF 2 CF(CF 3 )O· ROCF 2 CFO+CF 3 ·+ROCF 2 ·+A M = C 3 F 6 ; A = CF 2 O or CF 3 CFO The well known reaction scheme (1)–(5) [D. Sianesi, A. Pasetti, R. Fontanelli, G.C. Bernardi and G. Caporiccio, La chim. e l'ind. 55 (1973) 208–221] does not explain the experimental data obtained. Addition of equation (6) to this scheme yields the expression of the degree of PFE polymerization, with a qualitative description of the experimental data.