CONDUCTOMETRIC STUDIES OF ION BINDING TO POLY(OXYETHYLENE) IN METHANOL

The binding of alkali metal cation with poly(oxyethylene) was studied by means of conductometry in methanol. Apparent binding constants, KA, were determined by assuming the existence of discrete binding sites distributed every a monomer units along the polymer chain. KA increased in the order Li < Na < K < Cs < Rb. For large anions, such as thiocyanate or perchlorate, the formation of an ion pair complex was indicated. KA and α increased rapidly with decreasing salt concentration. This result was interpreted by the increased electrostatic repulsion between bound ions. The linear relationship between α1/2 and Cs-1/2 conforms to the Gaussian distribution of the segment between charges as well as to the partial retention of crystalline conformation of the poly(oxyethylene)-ion complex. © 1979 American Chemical Society.