New Inorganic-Organic Polymer Electrolytes based on PEG400 and Al[OCH(CH3)2]3 (part I): Synthesis and Vibrational Characterizations

Eleven new aluminum-based organically modified ceramics as polymer electrolytes were prepared and characterized. The hybrid inorganic-organic networks with the general formula {Al[O(CH2CH2O)8.7]ρ/(LiClO4)z}n , where 1.85 < ρ < 2.24 and 0 < z < 1.06, were prepared by a polycondensation reaction starting from aluminum isopropoxide and poly(ethylene glycol) (PEG400)/(LiClO4)y liquid polymer electrolytes with 0 < y < 0.49. Detailed compositional data, Fourier transform infrared (FTIR), and FT-Raman investigations allowed us to propose a structural hypothesis for this class of materials and to characterize the interactions between ions and binding sites in the host networks. These materials present a glassy rubbery consistency and consist of Al atoms bonded together by PEG400 bridges. Medium FTIR and FT-Raman studies of the polymers showed that the polyether moieties exhibit a TGT (T trans, G gauche) conformation with helical geometry and detected the presence of Li+ ... ClO4- ... Al[O(CH2CH2O)8.7]3 neutral species at cLi1/2>= 0.4 (mol/kg)1/2. We verified that in bulk {Al[O(CH2CH2O)8.7]ρ/(LiClO4)z}n complexes the acid aluminum cross-linking sites exhibit the anion trapping phenomenon toward perchlorate anions.