Enzymatic hydrolysis of semicrystalline poly(ethylene terephthalate) (PET) is hindered by the hydrophobic nature and crystallinity of the substrate, and it highly depends on the available interfacial area between substrate and aqueous phase. While most studies leverage particle size reduction to increase interfacial area, this study investigates the use of supercritical CO₂ (scCO₂) to increase internal surface area in PET, and its impact on the enzymatic hydrolysis yields. Our work shows that scCO₂ pretreatment of semicrystalline PET resulted in up to 2-fold higher terephthalic acid (TPA) yield relative to the untreated counterpart using Humicola insolens cutinase (HiC) enzyme. There is a positive correlation between the total pore surface area in the scCO₂-pretreated PET samples and the final TPA yield. In addition, preliminary kinetic studies revealed faster initial production of TPA for scCO₂-treated PET relative to untreated PET. ScCO₂-treated PET samples showed no significant changes in the crystalline content and thermal properties. However, NMR data indicated that scCO₂-treated PET has a slightly higher apparent number-average molecular weight (M_n) relative to that of untreated PET. Overall, scCO₂ pretreatment led to increased semicrystalline PET susceptibility to HiC enzyme action, resulting in increased TPA yields.

中文翻译：

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探讨超临界二氧化碳提高半结晶聚对苯二甲酸乙二醇酯的酶水解敏感性


半结晶聚对苯二甲酸乙二醇酯 (PET) 的酶促水解受到基材的疏水性和结晶度的阻碍，并且很大程度上取决于基材和水相之间的可用界面面积。虽然大多数研究利用粒径减小来增加界面面积，但本研究调查了使用超临界 CO ₂ (scCO ₂ ) 来增加 PET 的内表面积，及其对酶水解产率。我们的工作表明，与未使用特异腐质霉角质酶 (HiC) 酶处理的对应物相比，scCO ₂ 预处理半结晶 PET 的对苯二甲酸 (TPA) 产量提高了 2 倍。 scCO ₂ 预处理的 PET 样品中的总孔表面积与最终的 TPA 产率呈正相关。此外，初步动力学研究表明，相对于未处理的 PET，经过 scCO ₂ 处理的 PET 初始 TPA 生成速度更快。 ScCO ₂ 处理的 PET 样品的结晶含量和热性能没有显着变化。然而，NMR数据表明，相对于未处理的PET，scCO ₂ 处理的PET具有稍高的表观数均分子量(M _n )。总体而言，scCO ₂ 预处理导致半结晶 PET 对 HiC 酶作用的敏感性增加，从而导致 TPA 产量增加。