Influence of photooxidation on ionic reversible interactions of ionic poly(ether urethane)/silica hybrids

•Role of dynamic linkages within ionic nanocomposites during photoageing.•Silica nanoparticles in ionic nanocomposites have a prodegradant effect.•Ionic imidazolium-sulfonate crosslinks can be sustained under photooxidation. Organic-inorganic hybrids that combine the reversible nature of electrostatic interactions present in ionic systems with the reinforcement ability of nanoparticles in nanocomposites have the potential to revolutionize a wide spectrum of technologies. However, the prediction of their service lifetime under photooxidative conditions has remained elusive. In this paper, the accelerated environmental ageing of ionic hybrid materials made by combining imidazolium-functionalized poly(ethylene glycol)-based polyurethane (im-PU) and surface-modified sulfonate silica nanoparticles (SiO2-SO3H) is addressed. Since the resulting ionic nanocomposites are dynamic, the present contribution aims to elucidate their temporal behavior and precisely distinguish the contribution of the nanoparticles addition to the photochemical behavior. Although the addition of SiO2-SO3H nanoparticles within im-PU matrix led to faster photooxidative degradation, the ionic imidazolium-sulfonate crosslinks are thought to be sustained under photooxidative conditions. The results further suggest that the molecular weight loss and the resulting ductile-to-brittle transition for the ionic hybrid under atmospheric ageing conditions are attributed to severe chain scissions into the im-PU backbone in the presence of SiO2-SO3H nanoparticles. Overall, the present investigation suggests that the silica nanoparticles addition is responsible for the prodegradant effect rather than the presence of reversible ionic interactions in the system. The present work thus provides a deeper understanding about the crucial role of the incorporation of dynamic linkages within ionic nanocomposites during photochemical ageing and can aid the future design and use of these systems. [Display omitted]