Highly Tough, Barrier, and Biodegradable Copolyesters Synthesized from Furandicarboxylic Acid

Area of Science:

• Polymer Chemistry
• Materials Science
• Sustainable Plastics

Background:

• Biobased polyesters derived from 2,5-furandicarboxylic acid (FDCA) offer a sustainable alternative to conventional plastics.
• The primary limitation of FDCA-based polyesters, such as poly(ethylene furanoate) (PEF), is their inherent brittleness, hindering widespread application.
• Incorporating flexible units into the polymer backbone is a key strategy to overcome this brittleness.

Purpose of the Study:

• To synthesize novel high molecular-weight copolyesters based on FDCA by incorporating diethylene glycol (DEG).
• To investigate the impact of DEG content on the thermal stability, mechanical properties, optical transparency, and gas barrier performance of the resulting poly(ethylene-diethylene glycol 2,5-furandicarboxylate) (PEDF) copolyesters.
• To evaluate the enzymatic degradation characteristics of the synthesized PEDF copolyesters.

Main Methods:

• Synthesis of a series of PEDF copolyesters with varying DEG content.
• Characterization of thermal properties using techniques such as thermogravimetric analysis (TGA).
• Evaluation of mechanical properties including tensile strength, modulus, and elongation at break.
• Assessment of gas barrier properties for CO2 and O2.
• Enzymatic degradation studies using Candida antarctica Lipase B (CALB).

Main Results:

• PEDF copolyesters exhibited significantly improved thermal stability, mechanical properties, and optical transparency with increasing DEG content.
• The PEDF sample with 40% DEG (PED40F) showed a remarkable elongation at break of 43% (10.7 times that of PEF), alongside a tensile modulus of 2440 MPa and tensile strength of 74 MPa.
• PEDF demonstrated excellent gas barrier properties, with CO2 and O2 barrier improvement factors (BIFp) 13.0 and 7.3 times higher than PET, respectively.
• PED40F showed a mass loss of 45.79% after 49 days of CALB enzymatic degradation, indicating susceptibility to biodegradation.

Conclusions:

• The incorporation of DEG into FDCA-based polyesters effectively mitigates brittleness, leading to enhanced flexibility and mechanical performance.
• PEDF copolyesters present a promising class of biobased materials with superior gas barrier properties compared to PET.
• The tunable properties and susceptibility to enzymatic degradation position PEDF as a viable candidate for sustainable packaging and other plastic applications.