A High Performance Copolyester with “Locked” Biodegradability: Solid Stability and Controlled Degradation Enabled by Acid-Labile Acetal
Han Hu, Ying Tian, Zhengyang Kong, Wu Bin Ying, Chao Chen, Fenglong Li, Ruoyu Zhang, Jin Zhu
Abstract
The gradual degradation of polyester in daily use causes unpredictable failure and restricts its reliable applications. The realization of excellent stability in use and controlled degradation in a specific environment is highly appreciated but still remains challengeable. Here, we demonstrate a new solution via introducing acetal units into poly(butylene succinate): “locking” the biodegradation of copolyesters by rigid spiro diacetal, which could be “unlocked” in strong acidic circumstances. In detail, a series of poly(butylene succinate-co-spirocyclic succinate) (PBSS) copolyesters containing different contents of spiroglycol (SPG) were prepared and characterized. Among them PBSS65 behaved as an excellent candidate for future application, which possessed a high elastic modulus (1.87 GPa) and tensile strength (46 MPa) and moderate elongation at break (252%). It kept stable after melt processing and pH 0–14 soaking, showing solid reliability in daily use. Its biodegradation was locked by the steric hindrance effect of SPG units. Only after treatment in acetone/H2O mixed acidic solution could the biodegradation be triggered. Moreover, it was found that the prolongation of the acid treatment time could accelerate the biodegradation process. The controlled degradation mechanism was proposed to be consisted of acid cleavage of SPG unit and enzymatic degradation of ester group.