ION-BINDING PROPERTIES OF POLY(ETHYLENE OXIDE)-BASED NETWORKS IN DIOXANE AND TOLUENE

Binding constants of alkali picrates to poly(ethylene oxide)-based net works were measured spectrophotometrically in dioxane at 25 and 40 deg rees C. The networks were synthesized from aliphatic tri- or tetrafunc tional isocyanates and alpha,omega-diamino-poly(ethylene glycol)s. The slopes of the Klotz binding plots appear to decrease in the lower pic rate concentration range, suggesting that binding of the salt becomes more difficult at high picrate content. It was shown that under satura tion conditions six to seven ethylene oxide units are required to bind a sodium picrate ion pair. The affinity of the PEO-resins for the alk ali picrate can be enhanced by immobilizing a poly(crown ether) in the network. A number of competition experiments for sodium picrate in to luene was also carried out to obtain the affinity of soluble ligands f or alkali salts. (C) 1997 John Wiley & Sons, Inc.