Water-soluble biodegradable polyesters with pH and ionic responsivity

The synthesis of novel water-soluble polymers with biodegradability is an effective way to mitigate their negative environmental impacts. In this study, semi-aromatic copolyester poly(butylene succinate-co-butylene terephthalate) (PBST) with exceptional biodegradability is used as the resin matrix. Anionic sodium 1-3-isophthalate-5-sulfonate (SIPA) is introduced as a fourth monomer to prepare random poly(butylene succinate-co-butylene terephthalate-co-butylene 5-sodiosulfoisophthalate) (PBSTS) copolyesters by melt copolymerization. The incorporation of ionic groups enhances the hydrophilicity and water absorption of the copolyesters, resulting in water-soluble materials that exhibit ionic and temperature responsivity. Furthermore, the ionized biodegradable copolyesters demonstrate distinct pH-dependent degradation, which is accelerated at pH = 5.5 and 8.5 but inhibited at pH = 7.2. Degradation assessments in simulated body fluids reveal that the PBSTS copolyesters exhibit significant degradation in gastric fluids at pH = 1.5 with minimal degradation in intestinal fluids at pH = 6.8 and in body fluids at pH = 7.0. This unique degradation performance highlights the potential of these materials for addressing the challenges associated with selective drug delivery and localized controlled release in the human body.