Tailoring Architecture and Properties of Biodegradable Aliphatic-Aromatic Copolyesters via Interfacial Polymerization

Aliphatic-aromatic copolyesters (AAPEs) are widely used in biodegradable packaging due to their balance of thermal stability and enzymatic degradability. However, their synthesis is often hindered by time-consuming protocols, prolonged reactions, and reliance on expensive metal catalysts. Herein, we introduce stirred interfacial polymerization as a rapid, open-air method to synthesize poly(p-phenylene adipate-co-terephthalate) (PPAT) with tunable aliphaticity. We compare the use of chloroform, a conventional organic solvent for interfacial polymerization, with ethyl acetate, a more environmentally friendly alternative. Regardless of the solvent used, we achieved reaction yields that matched or exceeded those of traditional step-growth synthesis methods. Increasing the concentration of phase transfer catalyst enhances the incorporation of the aliphatic monomer, promoting a shift from a random to a more block-like copolymer structure. PPAT powder can be readily heat-pressed into semicrystalline films with degradation onset temperatures between 263 and 310 °C and tailored elastic moduli and hardness values. Furthermore, increased aliphaticity significantly improved enzymatic degradation by PETase, with films containing ∼60% of poly(p-phenylene adipate) units showing over 50% mass loss within 400 h. This work outlines an efficient synthetic pathway for producing enzymatically degradable AAPEs with tailored backbone structures, crystallinity, and thermomechanical properties.