Closed-loop recyclable and biodegradable thioester-based covalent adaptable networks

Area of Science:

• Materials Science
• Polymer Chemistry
• Sustainable Chemistry

Background:

• Dynamic covalent chemistry enables the design of adaptable and recyclable polymer networks.
• Developing materials with high service temperatures and environmental degradability is crucial for sustainable applications.

Purpose of the Study:

• To synthesize and characterize novel closed-loop recyclable and biodegradable aliphatic covalent adaptable networks (CANs).
• To evaluate the thermal stability, mechanical properties, and reprocessing capabilities of these CANs.
• To assess the natural biodegradation behavior of the developed materials.

Main Methods:

• Synthesis of aliphatic CANs utilizing dynamic β-CO thioester linkages.
• Mechanical testing including tensile strength, modulus, stress relaxation, and creep resistance.
• Thermal analysis to determine service temperature and reprocessing conditions.
• Biodegradation studies under natural conditions to quantify mass and strength loss over time.

Main Results:

• The developed CANs exhibit excellent recyclability and biodegradability with a service temperature exceeding 100 °C.
• Materials show significant stress relaxation above 100 °C, creep resistance, and low hysteresis loss.
• CANs are repeatedly reprocessable at 120 °C and depolymerizable to monomers under mild conditions.
• Significant mechanical strength (92.4%) and weight (76.5%) loss observed within approximately 35 days of natural biodegradation.

Conclusions:

• Aliphatic CANs based on dynamic β-CO thioester linkages offer a promising combination of high performance, reprocessability, and biodegradability.
• These materials represent a step towards sustainable polymer networks with extended service life and environmentally benign end-of-life options.