Harnessing Colloidal Dispersion for Laccase-Driven Enzymatic Depolymerization of Polystyrene

Area of Science:

• Polymer Chemistry
• Biocatalysis
• Environmental Science

Background:

• Polystyrene (PS) is a widely used synthetic polymer with high global production.
• Its stable chemical structure makes it resistant to conventional recycling and degradation methods.
• There is a critical need for sustainable methods to depolymerize and recycle PS.

Purpose of the Study:

• To develop an efficient and sustainable method for polystyrene depolymerization.
• To demonstrate the feasibility of using a laccase-mediator system (LMS) under mild, aqueous conditions.
• To overcome challenges in substrate accessibility for polymer degradation.

Main Methods:

• Formulating polystyrene into colloidally stable nanoparticles to enhance surface area and accessibility.
• Utilizing a laccase-mediator system (LMS) comprising Trametes versicolor laccase, 1-hydroxybenzotriazole (HBT), and ambient oxygen.
• Investigating the depolymerization mechanism through mechanistic studies, including hydrogen atom transfer (HAT) and beta-scissions.

Main Results:

• Achieved up to a 99.9% decrease in molar mass for polystyrene synthesized via emulsion polymerization.
• Demonstrated the effectiveness of the colloidal dispersion strategy for both synthesized and commercial polystyrene waste.
• Confirmed efficient depolymerization under mild aqueous conditions, utilizing ambient oxygen and a native enzyme.

Conclusions:

• The developed LMS approach offers an efficient proof-of-concept for polystyrene depolymerization.
• This method provides a sustainable alternative to harsh chemical treatments, using mild aqueous conditions.
• The strategy of formulating PS into nanoparticles is key to enabling efficient biocatalytic degradation.