Triethanolamine copolymerization of degradable polyesters for enhanced degradation, oxidation-accelerated hydrolysis and fiber formation

Abstract

The development of degradable plastics is crucial for addressing the issue of plastic pollution. Although poly(butylene adipate terephthalate) (PBAT) is a degradable polyester, it has stringent environmental requirements for degradation and necessitates urgent modification. Triethanolamine (TEOA), an inexpensive industrial product, was introduced into the molecular chain of PBAT to facilitate branching and enhance catalytic synergy. poly(butylene adipate terephthalate - triethanolamine) (PBAT-TEOA) with TEOA contents ranging from 0.25% to 4% were synthesized. The results indicate that the introduction of triethanolamine significantly shortens the polycondensation time while maintaining favorable coloration (b value < 10). Additionally, the mechanical properties of the copolyester can be slightly improved with minimal TEOA incorporation. Specifically, PBAT-TEOA_0.5 exhibits a tensile strength of 20.96 MPa. However, this strength declines rapidly when TEOA content exceeds 1%. Furthermore, TEOA enhances both the hydrophilicity and enzymatic as well as hydrolytic properties of the copolyester. Notably, PBAT-TEOA_0.25 underwent hydrolysis in PBS buffer over a period of 49 days, resulting in a mass residual rate of 89.86%. The branched structure can be disrupted through the Cope elimination reaction, thereby accelerating degradation following treatment with hydrogen peroxide (H₂O₂). The number average molecular weight of PBAT-TEOA₂ decreases by 35.53% after the oxidative treatment. Finally, melt spinning was conducted on PBAT-TEOAs to prepare degradable polyester fibers with a fiber strength of 1.98 cN/dtex. This work presents a straightforward, efficient and cost-effective strategy for enhancing both the degradation performance and spinnability of PBAT with good coloration.