Synthesis and characterization of aspartate polymer complexes

Abstract

Oligomeric polyester, namely poly(tetramethylene asparate) (PTMA), was synthesized From D,L-aspartic acid and 1,4-butanediol by a melt codensation technique. Polyester–metal complexes were synthesized by the reaction of PTMA with hydrated acetates of Fe(III), Pd(IV), and UO2(II) in DMSO. The polyester–metal complexes were characterized by elemental analysis, UV–Vis, IR spectral studies, magnetic susceptibility measurements and 1H-NMR. Mossbauer spectra of mixed samples of Pd-PTMA and Fe(II)-PTMA with a ratio of 1 : 2 mol showed the iron(III) oxide formed in early stages of the decomposition at 250°C is mainly fine-grained and as the temperature is increased, well-crystalline hematic is formed. Above 250°C, the Mossbauer spectrum showed the typical six-line pattern of magnetically oriented Fe(III) oxide, but at 800°C, the spectrum showed quadrupole interaction characteristic of PdFe2O4 spinel. The metal ions were found to be six—coordinated with two water molecules as additional ligands besides oxygen and nitrogen atoms of polyester repeating units. Thermogravimetric analysis (DTA-TG) showed that co-ordination polymers are thermally more stable than polyester; the activation parameters for both decomposition steps were calculated and discussed. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 942–947, 2004