Ioannidis Rafail O, Bikiaris Nikolaos D, Vouvoudi Evangelia, Zamboulis Alexandra, Nikolaidis Nikolaos, Bikiaris Dimitrios N
Laboratory of Polymer and Colors Chemistry and Technology, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki, Greece.
Polymers (Basel). 2025 May 16;17(10):1374. doi: 10.3390/polym17101374.
Poly(lactic acid) (PLA) is a widely used biobased polyester which can be derived from renewable resources. Due to its excellent properties, it has already been adopted in various industrial sectors. While PLA is compostable, its degradation to the environment is very slow, necessitating the development of efficient recycling methods. This study focuses on the chemical recycling via microwave-assisted alkaline hydrolysis of PLA and its copolymers with poly(ethylene azelate) (PEAz), aiming to recover both carboxylic acid monomers: lactic acid and azelaic acid. Moreover, our method tunes the degradation of PLA via the synthesis of the novel aliphatic PLA-based copolyesters, targeting engineering-like applications, specifically in the field of printed electronics. Various process parameters were analyzed, including the temperature and the duration of the experiments as well as different phase transfer catalysts. Complete degradation was achieved at low temperatures (110-125 °C) and short times (12-15 min) for the PLA-based copolyesters, offering significant environmental benefits, as considerably less energy is consumed compared to chemical conventional methods. So, by changing the composition of the copolyesters through the incorporation of PEAz blocky segments, the ester bonds became more susceptible to hydrolysis under alkaline conditions assisted with microwave irradiation. Additionally, enzymatic hydrolysis was also studied in parallel for comparative purposes, revealing low degradation rates, thus establishing the microwave-assisted alkaline hydrolysis as a solid and reliable method for tuning the degradation of PLA-based materials.
聚乳酸（PLA）是一种广泛使用的生物基聚酯，可从可再生资源中提取。由于其优异的性能，它已被应用于各个工业领域。虽然PLA可堆肥，但它在环境中的降解非常缓慢，因此需要开发高效的回收方法。本研究重点关注通过微波辅助碱性水解PLA及其与聚壬二酸乙二酯（PEAz）的共聚物进行化学回收，旨在回收两种羧酸单体：乳酸和壬二酸。此外，我们的方法通过合成新型脂肪族PLA基共聚酯来调节PLA的降解，目标是工程类应用，特别是在印刷电子领域。分析了各种工艺参数，包括实验温度、持续时间以及不同的相转移催化剂。对于PLA基共聚酯，在低温（110 - 125°C）和短时间（12 - 15分钟）内实现了完全降解，与传统化学方法相比，能耗大大降低，具有显著的环境效益。因此，通过引入PEAz嵌段来改变共聚酯的组成，在微波辐射辅助的碱性条件下，酯键更容易水解。此外，为了进行比较，还并行研究了酶水解，结果显示降解率较低，从而确立了微波辅助碱性水解作为调节PLA基材料降解的一种可靠方法。
