Metal-Organic Framework-Gated Biocatalysis Enables Triggered Depolymerization of Melt-Processed Polyesters

Controlling biocatalytic activity in melt-processed polymers is a central challenge for triggered depolymerization, because enzymes deactivate at melt-extrusion temperatures. Here, metal-organic framework-gated biocatalysis, achieved by encapsulating enzymes within zeolitic imidazolate framework-8 (ZIF-8), preserves > 85% activity after 2 min at 180°C while regulating substrate access. Enzyme@ZIF-8 biocomposite production scales to ∼50 kg day^{- 1} and is compounded by twin-screw extrusion into poly(ε-caprolactone) (PCL), poly(butylene adipate-co-terephthalate) (PBAT), and polylactide (PLA) at a tonne-per-day scale; pellets are compatible with standard thermoforming. The enzyme@ZIF/plastic composites retain mechanical performance comparable to the neat polymers during processing and use. At the end-of-life, chemical triggers dissolve the ZIF-8 gate, releasing the enzyme, Zn^{2 +} and imidazolate to cooperatively accelerate depolymerization. Degradation increases 13.3-62.8-fold for PCL and PLA in water and 1.7-fold under industrial composting for PBAT and enables anaerobic PBAT digestion, whereas pristine polyesters show negligible conversion. This melt-processable platform establishes gated, on-demand depolymerization compatible with industrial polymer manufacturing.