Chemo-Enzymatic Depolymerization of Functionalized Low-Molecular-Weight Polyethylene

Area of Science:

• Polymer Chemistry
• Biocatalysis
• Environmental Science

Background:

• Polyethylene (PE) is a prevalent plastic contributing to global waste.
• The inert nature of PE's carbon backbone hinders enzymatic degradation and biocatalytic recycling.
• Developing effective recycling methods for PE waste remains a significant challenge.

Purpose of the Study:

• To demonstrate the enzymatic depolymerization of low-molecular-weight polyethylene (LMW PE).
• To explore a multi-enzyme cascade approach for breaking down PE waste.
• To investigate a novel bio-based recycling strategy for polyolefins.

Main Methods:

• Chemical pretreatment of LMW PE using m-chloroperoxybenzoic acid (mCPBA) and ultrasonication.
• Enzymatic depolymerization employing a cascade of catalase-peroxidase, alcohol dehydrogenase, Baeyer Villiger monooxygenase, and lipase.
• Analysis of polymer conversion using Gas Chromatography-Mass Spectrometry (GC-MS) and weight loss determination.
• Characterization of LMWPE-nanoparticles using Atomic Force Microscopy (AFM).

Main Results:

• Achieved approximately 27% polymer conversion in gram-scale experiments.
• Formation of medium-sized functionalized molecules, including ω-hydroxycarboxylic acids and α,ω-carboxylic acids.
• Enzymatic depolymerization led to a reduction in the size of mCPBA- and enzyme-treated LMWPE-nanoparticles.

Conclusions:

• A multi-enzyme catalytic system, combined with chemical pretreatment, can depolymerize LMW PE.
• This approach represents a novel starting point for developing bio-based recycling methods for polyolefin waste.
• The study highlights the potential of enzymatic strategies for addressing plastic waste challenges.