ESR of intermediate radicals in thermolysis mechanisms: peroxidic perfluoro polyethers

The photothermolysis between 100 and 250 C of polymers with perfluorooxymethylene, oxyethylene and oxypropylene structures and containing peroxidic units as photoactive initiators has been studied by ESR and the INDO MO method. Following the initial homolysis of peroxidic bonds and the beta scission of resulting alkoxy radicals, alkoxyfluoroalkyl radicals are formed wich, above 100 C, undrgo thermal decomposition by beta scission, initiating a chain depolymerization with formation of carbonyl compounds and C2F4 and C3F6 monomers; the latter add to RCF2. species yielding Cn (n>=3) units. By extension of these results, it is inferred that this mechanism is of major importance in the high-temperature pyrolisis of this class of compounds. Among the intermediates of the C2P and C3P photothermolysis, of special interest are some novel prymary alkoxyfluoroalkyl radicals with strongly bent structures at the radical centers and showing unusually large long-range interactions with gamma and delta fluorine atoms, wich are actually being investigated by MO methods.