Unraveling thermo-oxidation degradation pathways of polymers by in-situ differentiating the alkyl-related reactive oxygen radicals

Luminescence dynamic fitting was proposed to in-situ distinguish the RO• and ROO• radicals for unraveling the thermo-oxidation pathways for polymers. • Luminescence dynamic fitting strategy was proposed to in-situ distinguish thermo-oxidation pathways of polymers. • RO• and ROO• have been distinguished based on two luminescence dynamic fitting equations. • Route transformation during thermo-oxidation of polymers under different oxygen-containing environment could be identified. Alkoxy radicals (RO•) and peroxy radicals (ROO•) are generated during thermo-oxidation of polymers under oxygen environment, leading to RO•-dominated or ROO•-dominated reaction pathways with severely deteriorated polymer chains or terminated reaction. However, it has been a long-standing challenge to in-situ distinguish RO• and ROO• radicals due to their short-lived lifetime. In principle, chemiluminescence (CL) deserves to become an efficient strategy for in-situ monitoring for various radicals. However, it fails to differentiate RO• and ROO• radicals due to their fully overlapping emission wavelengths. In this contribution, we have proposed a CL dynamic fitting strategy to distinguish RO• and ROO• radicals of in-situ production during thermal oxidation under the different oxygen-containing environment. Based on two equations, ln I = ln A · k R O - ln 1 + Y · e - k RO t , and ln I = ln B - k R O O t - 2 · ln 1 + Y · e - k R O O t , respectively, the CL dynamic fitting was implemented to identify RO• and ROO• generated during the oxidative reactions of polymers. It is anticipated that the proposed strategy could be further explored for the identification of other radicals during thermo-oxidation, providing possibilities for regulating oxidative reaction pathways of polymers.