Coupling Photoluminescence and Ionic Conduction Properties Using the Different Coordination Sites of Ureasil-Polyether Hybrid Materials

Abstract

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 Eu 3+ 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 Eu 3+ ) and co-doped (using Li + and Eu 3+ ) U-PEO and U-PPO hosts showed that in every case, there was specific coordination of Eu 3+ 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 Eu 3+ -loaded OIH. Although loading with Eu 3+ 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.