Synthesis and properties of hydrophilic polymers. Part 7. Preparation, characterization and metal complexation of carboxy-functional polyesters basedon poly(ethylene glycol)

Novel water-soluble polyesters with pendant carboxylic groups were synthesi zed by polycondensation of ethylenediaminetetra-acetic acid (EDTA) dianhydr ide and diethylenetriamine-penta-acetic acid (DTPA) dianhydride with poly(e thylene glycol)s of different chain-lengths. Two experimental approaches (p olycondensation using various solvents and in the melt) were studied, and m elt condensation was found to give higher yields of polyesters. The polymer ic products were soluble in water, acetone, chloroform and toluene, and wer e characterized by elemental analysis, IR and NMR spectroscopy. In addition , the carboxyl functionalities were determined by titration and the hydroly tic stability studied as a function of pH. The complexing capacity of the f unctional polyesters was determined in dependence of pH for copper in aqueo us solution using the Liquid-Phase Polymer-Based Retention (LPR) technique and found to be 257mgg(-1) for the EDTA-based copolymer at pH5 and 230mgg(- 1) for the DTPA-based copolymer, respectively. (C) 1999 Society of Chemical Industry.