High-Molecular-Weight and Light-Colored Disulfide-Bond-Embedded Polyesters: Accelerated Hydrolysis Triggered by Redox...

Area of Science:

• Polymer Chemistry
• Materials Science
• Sustainable Polymers

Background:

• Disulfide bonds offer reduction responsiveness but pose challenges in melt polycondensation due to poor thermal stability.
• Developing disulfide-bond-based polyesters requires overcoming inherent S-S bond instability during processing.

Purpose of the Study:

• To synthesize disulfide-bond-based polyesters (PBSDi) via melt polycondensation with improved thermal stability.
• To evaluate the properties, processability, and degradation behavior of the novel PBSDi materials.
• To explore the potential of PBSDi as high-performance biodegradable packaging materials.

Main Methods:

• Melt polycondensation to synthesize poly(butylene succinate-co-dithiodipropionate) (PBSDi).
• Characterization of molecular weight, thermal stability (T_d,5%), crystallizability, and lamellar thickness.
• Mechanical and barrier performance testing compared to commercial poly(butylene adipate-co-terephthalate) (PBAT).
• Enzyme and hydrolysis degradation studies, including response to H2O2 oxidation.
• Computational analysis (Fukui function, DFT) and noncovalent interaction analysis to understand degradation mechanisms.

Main Results:

• Successfully synthesized PBSDi with high molecular weights (up to 84.7 kg/mol) and good thermal stability (T_d,5% > 318 °C).
• PBSDi exhibited good crystallizability and superior mechanical and barrier properties compared to PBAT.
• Disulfide bonds accelerated enzyme degradation and showed tunable hydrolysis rates upon oxidation (to sulfoxide/sulfone) in H2O2.
• Glutathione triggered rapid polymer-to-oligomer degradation, confirmed by molecular weight decline.

Conclusions:

• Overcame thermal stability challenges for disulfide-bond-based polyesters via melt polycondensation.
• Developed high-performance, melt-processable biodegradable polyesters (PBSDi) with tunable degradation.
• PBSDi shows significant promise for advanced biodegradable packaging applications requiring on-demand degradation.