Synthesis and Characterization of Novel Hydrolytically Degradable Polyesters

Abstract

Six novel hydrolytically degradable polyesters were synthesized from thiodipropionic acid (TDPA) and five diols by melt polycondensation, and characterized by FT-IR, ¹H NMR, gel permeation chromatography, differential scanning calorimetry and thermogravimetry analysis. The polystyrene-equivalent number-average (M _n) and weight-average molecular weight (M _w) of these polyesters ranged from 4 900–11 100 Da and 7 900–20 879 Da, respectively, with PDI values of 1.48–1.98. The melting point varied from 62.3–127.9°C, and the 50% mass-loss temperature ranged between 387–417°C. The degradation of these polyesters was studied in terms of relative weight loss in distilled water at different pH. Weight losses of 14%–26% were obtained at pH 7.0, 26%–38% at pH 6.0, and 32%–43% at pH 8.3 over a 20-week period. The ecotoxicity study suggested that safety of the synthesized polyesters for the eisenia foetida. These results indicate that these polyesters have a combination of good thermal and degradability behaviors, which can be tailored through selection of the diol monomers used in the synthesis.

Keywords

thiodipropionic acid / water-degradable polyester / melt polycondensation / thermal properties / degradability tailoring