Anion-binding calixarene receptors: Synthesis, microstructure, and effect on properties of polyether electrolytes

(Chemical Equation Presented) In the present paper, a novel lithium-conducting polymer electrolyte, based on the low molecular weight dimethoxy poly(ethylene oxide) matrix as well as high molecular weight poly(ethylene oxide), is studied. New calixarene derivatives have been designed, synthesized, and successfully applied as neutral anion-binding receptors in the electrolytes, what could be of interest in the search for new sensors as well as for enhancing electrolytic functionality in energy-storage devices. Herein, details regarding synthesis and structural properties of all compounds incorporated in the polyether system are presented and discussed. The effect of supramolecular additives on physical (e.g., the charge-carriers transport mechanism, mechanical and thermal properties, or degree of crystallinity) and chemical (e.g., ion-receptor ion-matrix interactions) characteristics of polymer electrolyte is investigated in terms of differential scanning calorimetry, Fourier-transform IR spectroscopy, and impedance spectroscopy results. In particular, it was established that binding anions by some of the receptors under study may enhance ionic dissociation and after all increase the relative fraction of mobile lithium cations, leading to a transference number close to 1. Iodide anions complexing by the supramolecular additive were also found to be responsible for stabilization of the solid electrolyte-electrode interface. Its nature is discussed.