Poly(butylene‐ co ‐cyclohexanedimethylene oxalate): A Rapidly Degradable Copolymer With Thermal Stability

The accumulation of plastic waste in marine environments poses a significant ecological threat, highlighting the urgent need for intrinsically hydro‐degradable polymers. Poly(butylene oxalate) (PBO) hydrolyzes rapidly but its degradation rate is too fast for practical applications. To address this challenge, rigid cyclohexanedimethanol (CHDM) units were introduced into the PBO backbone to synthesize a series of poly(butylene cyclohexanedimethylene oxalate) (PBCO) copolyesters with CHDM content ranging from 19.3 to 75.3 mol%. Their chemical structure, crystallization behavior, thermal and mechanical properties, rheology, and degradation profile were systematically investigated. Results indicated that CHDM incorporation significantly affects properties: crystallinity, melting point, and mechanical strength exhibit a V‐shaped trend with increasing CHDM content, whereas thermal stability, glass transition temperature, and melt viscosity increase monotonically. Notably, the seawater degradation rate displays a unique non‐monotonic trend, initially accelerating and then substantially slowing as CHDM content increases. The decomposition temperature decreased by 58.8°C, elongation at break increased by 64%, and degradation rate reduced, collectively extending the material's applicable window. This work demonstrates a viable strategy for finely tuning the degradation profile, thermal and mechanical properties of aliphatic polyesters via rigid‐unit copolymerization, offering a promising material solution that balances service life and hydrolytic degradability for specific applications.