Coupling Photoluminescence and Ionic Conduction Properties Using the Different Coordination Sites of Ureasil–Polyether Hybrid Materials
Résumé
In this article, we demonstrate that each functional group of ureasil organic–inorganic hybrid (OIH) materials can act as a specific coordination site for a given active guest species, hence allowing the possibility of combining different functional properties. To illustrate this concept, the sol–gel process was used to produce diurea cross-linked siloxane–polyethylene oxide (U–PEO) and siloxane–polypropylene oxide (U–PPO) hybrid host frameworks with similar molecular weights (1900 and 2000 g mol–1 for PEO and PPO, respectively), with Li+ and Eu3+ as active guest ions providing ionic conduction and photoluminescence (PL) properties, respectively. Comparison of Fourier transform infrared spectra and small-angle X-ray scattering results for single-doped (using Li+ or Eu3+) and co-doped (using Li+ and Eu3+) U–PEO and U–PPO hosts showed that in every case, there was specific coordination of Eu3+ by the carbonyl group of the urea bridge and of Li+ by ether-type oxygen of the PEO and PPO chains. Optical analyses demonstrated that loading with Li+ did not affect the luminescence properties of the Eu3+-loaded OIH. Although loading with Eu3+ had a small effect on ionic transport, co-doping with Li+ ions ensured macroscopic ion-conduction of the transparent and luminescent hybrid material. The results suggested that the combination of both properties in a transparent elastomeric material could be useful for the development of multifunctional devices. The results suggested that the combination of both properties in a transparent elastomeric material could be useful for the development of multifunctional polyelectrolytes applied in the field of dual luminescent devices such as photoelectrochromic smart windows.