Synthesis, characterization and conductivity studies of Li and Mg polymer electrolytes based on esters of ethylenediaminetetraacetic acid and PEG400

Two distinct types of host polymers, [EDTA]3[PEG400]2, and [EDTA][PEG400]2, consisting of polyethereal chains linked together by EDTA chelating units, were synthesized from ethylenediaminetetraacetic acid (EDTA) derivatives and PEG400. Their structures were revealed by analytical data, viscosimetric measurements and FTIR studies. Direct dissolution of delta-LiCl and delta-MgCl2 in these prepared host polymers resulted in the following electrolytic complexes: [EDTA]3[PEG400]7/(LiCl)6.39, [EDTA]3[PEG400]7/(MgCl2)8.23, [EDTA]3[PEG400](7)/(LiCl)6.39(MgCl2)6.16, [EDTA][PEG400]2/(LiCl)2.26, [EDTA][PEG400]2/ (MgCl2)1.98 and [EDTA][PEG400]2/(LiCl)2,26(MgCl2)1.98. Mid- and far-FTIR spectroscopic studies revealed the following properties for all the electrolytic complexes: (a) the polyethereal chains are in the TGT conformation; (b) the Mg2+ ion could be hexa- or heptacoordinated in chelating sites of EDTA; (c) the Li+ ion is preferentially coordinated by the oxygen atoms of the residual acetate groups and polyethereal moieties. Results of conductivity measurements performed at room temperature indicated that the proposed Mg polymer electrolytes (PE) might be very useful for the development of electrochemical transducers for measuring water hardness.