Bio-based and biodegradable polymers opens up opportunities to overcome resource depletion and plastic pollution. However, the degradation mechanism based on ester bond breakage makes it difficult to achieve controllable degradation induced by external stimuli. In this work, we present a new 2,5-furandicarboxylic acid-based copolyesters (PBFDi) by partially replacing carbon–carbon backbones with disulfide bonds and discuss the influence of disulfide bonds on thermal stability, crystallization behavior, mechanical and barrier properties of polyesters. They could maintain stable for 1 h at processing temperatures of 220 °C, meeting the needs of long-term melt processing. The asymmetric structure of the furan ring and the slower free rotation of disulfide bonds help restrict the mobility of chains and obstruct gas permeation, resulting in 9.3–126.7 times increase in O barrier than commercial PBAT. With the introduction of small amount (≤40 %) of disulfide bond units, the hydrolysis rate is relatively slow and can maintain stable during storage and use. As expected, the copolyesters show redox dual-responsive degradation. Even at low concentrations (0.01 M and 0.1 M) of HO, the transition from hydrophobicity to hydrophilicity can be achieved, expected to accelerate the hydrolysis of PBFDi. The fast cleavage of disulfide bonds induced by DTT could be influenced by the copolymerized FDCA units. Lastly, the redox dual-responsive mechanism is elucidated, and how the rigid FDCA co-monomers affect the redox dual responsiveness is also clarified.

中文翻译：

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基于2,5-呋喃二甲酸和二硫键的高阻隔聚酯：低浓度氧化还原剂诱导的智能降解


生物基和可生物降解聚合物为克服资源枯竭和塑料污染提供了机会。然而，基于酯键断裂的降解机制很难实现外部刺激诱导的可控降解​​。在这项工作中，我们通过用二硫键部分取代碳-碳主链，提出了一种新型2,5-呋喃二甲酸基共聚酯（PBFDi），并讨论了二硫键对聚酯热稳定性、结晶行为、机械和阻隔性能的影响。它们可以在220°C的加工温度下保持稳定1小时，满足长期熔融加工的需要。呋喃环的不对称结构和二硫键较慢的自由旋转有助于限制链的移动性并阻碍气体渗透，导致 O2 阻隔性比商业 PBAT 增加 9.3-126.7 倍。由于引入了少量（≤40%）二硫键单元，水解速度相对较慢，在储存和使用过程中能保持稳定。正如预期的那样，共聚酯表现出氧化还原双响应降解。即使在低浓度（0.01 M 和 0.1 M）的 H2O 下，也可以实现从疏水性到亲水性的转变，有望加速 PBFDi 的水解。 DTT 诱导的二硫键快速断裂可能受到共聚 FDCA 单元的影响。最后，阐明了氧化还原双响应机制，并阐明了刚性FDCA共聚单体如何影响氧化还原双响应性。