Hydrolyzable aromatic copolyesters of p-dioxanone.

Area of Science:

• Polymer Chemistry
• Materials Science

Background:

• Ring-opening polymerization is a versatile method for synthesizing polyesters.
• Controlling copolymer composition and microstructure is crucial for tailoring material properties.

Purpose of the Study:

• To prepare random copolyesters with varying ratios of aromatic (hexamethylene terephthalate - HT) to aliphatic (p-dioxanone - DO) units.
• To characterize the composition, microstructure, thermal properties, and degradation behavior of these novel copolyesters.

Main Methods:

• Entropically driven ring-opening copolymerization of cyclic oligo(hexamethylene terephthalate)s and p-dioxanone.
• Composition and microstructure analysis using 1H and 13C Nuclear Magnetic Resonance (NMR) spectroscopy.
• Thermal analysis (degradation and glass transition temperatures) and X-ray diffraction for crystallinity assessment.
• Hydrolytic degradation studies in an aqueous medium.

Main Results:

• Random copolyesters with HT:DO ratios ranging from 9 to 1.3 were successfully synthesized.
• NMR confirmed accurate control over comonomer incorporation and microstructure.
• Thermal properties (Tg, Td) correlated well with composition.
• Crystallization was observed for DO content below 30%, adopting the poly(hexamethylene terephthalate) crystal structure.
• Copolyesters showed superficial hydrolytic degradation with water-soluble dioxanoic acid release.

Conclusions:

• Entropically driven ring-opening copolymerization provides a route to tunable aromatic-aliphatic copolyesters.
• The synthesized copolyesters possess predictable thermal and crystallization behaviors based on their composition.
• The materials exhibit hydrolytic degradability, a key characteristic for potential biomedical applications.