Photodegradation of polyglycidol in aqueous solutions exposed to UV irradiation

The photodegradation of polyglycidol in aqueous solution with UV wavelength of 254 nm was investigated. The experiments were carried out in air at a constant temperature and the photodegradation of polyglycidol (PGl) was compared to that of poly(ethylene oxide) (PEO), the most widely studied polyether. Size exclusion chromatography with multiangle light scattering detection (SEC-MALLS) was used to measure the changes in the molar masses and molar mass dispersities of polymers during degradation. The molar mass of PGl decreased dramatically during the first period of UV irradiation and then gradually approached a limiting value of 17,000 g/mol, regardless of the initial polymer concentration. PEO was less sensitive to UV irradiation than polyglycidol however, both polymers degrade mainly via chain scission. The degradation of PGl and PEO leads to acidification of their water solution. The photooxidation products were analyzed by FTIR and NMR spectroscopy and the spectrophotometric results revealed that the irradiation of the polymers led to the formation of carbonyl groups in the macromolecular chains. A mechanism accounting for the main routes of PGl photooxidation is proposed.