Photo-oxydation de polyéther-bloc-polyamides, 3. Propriétés des hydroperoxydes dans les homopolym`res de polyéthers correspondants

The photooxidation of poly(tetramethylene glycol) (PTMG), poly(propylene glycol) (PPG) and poly(ethylene glycol) (PEG) was studied at 60°C applying wavelengths longer than 300 nm. Hydroperoxy groups were found to accumulate in high photostationary concentration in PTMG and were decomposed essentially into formate groups. Hydroperoxides were observed in low photostationary concentration in PEG and PPG. Decomposition of the PPG hydroperoxides into formate groups showed that hydroperoxidation occurs, surprisingly, at the secondary carbon atom of the propylene glycol monomeric unit, rather than at the tertiary carbon. These results account for the large variation in the properties of hydroperoxides observed throughout the photooxidation of polyether-block-polyamides of various composition.