Efficient Depolymerization of Poly(ethylene 2,5-furanoate) Using Polyester Hydrolases

Area of Science:

• Biopolymer science
• Enzymatic catalysis
• Sustainable materials

Background:

• Poly(ethylene 2,5-furanoate) (PEF) is a promising biobased alternative to PET, offering environmental benefits.
• Limited information exists on PEF's recyclability, crucial for its industrial adoption.
• Enzymatic depolymerization is a potential sustainable recycling pathway for polyesters.

Purpose of the Study:

• To investigate the enzymatic depolymerization of PEF using PET hydrolases.
• To evaluate the efficiency of FastPETase and leaf compost-cutinase (LCC) for PEF breakdown.
• To understand the influence of PEF crystallinity on enzymatic hydrolysis.

Main Methods:

• Depolymerization of PEF films using FastPETase and LCC at reduced enzyme loadings.
• Optimization of reaction conditions (temperature, buffer) for maximum depolymerization.
• Analysis of depolymerization extent via weight loss and quantification of 2,5-furandicarboxylic acid (FDCA) production.
• Microscopy studies to assess surface erosion and the impact of crystallinity.

Main Results:

• Near-complete depolymerization of PEF achieved with LCC (98% weight loss) and FastPETase (up to 92% weight loss) under optimized conditions.
• LCC demonstrated superior performance over FastPETase in both FDCA release and weight loss.
• Crystallinity significantly hindered enzymatic hydrolysis, with only 4-7% weight loss observed for crystalline PEF.
• Main products identified as FDCA, ethylene glycol, and mono(2-hydroxyethyl)-furanoate.

Conclusions:

• FastPETase and LCC are effective enzymes for the depolymerization of PEF, even at significantly lower loadings.
• LCC shows higher efficiency for PEF enzymatic hydrolysis compared to FastPETase.
• PEF crystallinity presents a challenge for enzymatic recycling, requiring further investigation.
• This study provides critical insights for developing viable enzymatic recycling processes for biobased PEF.