High‐Performance and Easy Processable Poly(Ethylene Oxalate) Synthesized via in Situ Copolymerization

ABSTRACT A dual‐component catalytic system comprising p‐toluenesulfonic acid (p‐TSA) and antimony ethylene glycolate (AEG) was employed to regulate the content of diethylene glycol (DEG) structural units in the main chain of poly(ethylene oxalate) (PEOx) during melt polycondensation. The experimental results demonstrate that p‐TSA‐catalyzed etherification effectively promotes ethylene glycol dehydration, significantly increasing the mole fraction of DEG units in PEOx from 2.9% to 15.2%. This structural modification disrupts polymer chain regularity, reducing the melting point of PEOx from 179.9°C to 152.7°C, while maintaining decomposition temperature stability near 260°C, thereby substantially broadening the processing window. Concurrently, intrinsic viscosity shows a significant increasing trend with rising DEG content, and the elongation at break increases from 4.2% to 541.5%. The water vapor barrier coefficient remained below 3.1 × 10 −14 g·cm/cm 2 ·s·Pa, outperforming most biodegradable polyesters. Precise regulation of DEG content effectively balances processability and performance metrics, providing critical theoretical and technical foundations for novel marine‐degradable plastics. The successful synthesis of low‐melting‐point PEOx not only addresses the narrow processing‐window limitation inherent to traditional poly(oxalate)s but also highlights the substantial practical potential of biodegradable plastics for marine environmental protection.