Abstract The poor hydrophobicity and toughness of polylactide (PLA) films make it difficult to meet the requirements of barrier, printing and moisture-proof material. How to improve the two drawbacks of PLA simultaneously is a daunting challenge at present. In this work, we introduce poly (butylene adipate-co-terephthalate) (PBAT) as a second flexible phase into PLA matrix and concomitantly impose intensive elongational flow by two-stage drawing. Under the elongational flow field, the PLA/PBAT film can form the oriented structure combining in-situ nanofibrils with oriented lamellae, exhibiting excellent stiffness-toughness balance. Then surface treatment via moderate alkaline etching makes the micro/nano structure expose on the surface, which can effectively improve the hydrophobicity of the surface. We further investigates the influence of blend composition, drawing ratio and etching time on the oriented structure, mechanical and wetting properties. It is found that the PLA/PBAT film with the weight ratio of 70/30, low draw ratio of 2.7 and etching time of 24 h has the optimal properties, which possesses Young's modulus of 2.53 GPa, yield strength of 51.9 MPa, elongation of break of 131.8% and water contact angle of 131.8°. It is noteworthy that the film can mainly keep original mechanical after surface treatment. This work could offer a facile and effective method to fabricate the green PLA based film with good mechanical properties and hydrophobicity in a large scale.

中文翻译：

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用聚（己二酸丁二酯-共对苯二甲酸酯）原位纳米原纤维调节聚丙交酯复合薄膜的润湿性和机械性能

摘要 聚乳酸（PLA）薄膜的疏水性和韧性较差，难以满足阻隔、印刷和防潮材料的要求。如何同时改善PLA的两个弊端，是目前一项艰巨的挑战。在这项工作中，我们将聚（己二酸丁二醇酯-共对苯二甲酸酯）（PBAT）作为第二个柔性相引入 PLA 基质中，并通过两阶段拉伸同时施加强拉伸流。在伸长流场下，PLA/PBAT 薄膜可以形成原位纳米原纤维与定向薄片相结合的定向结构，表现出优异的刚度-韧性平衡。然后通过适度的碱性蚀刻进行表面处理，使微/纳米结构暴露在表面，可以有效提高表面的疏水性。我们进一步研究了共混物成分、拉伸比和蚀刻时间对取向结构、机械和润湿性能的影响。发现重量比为 70/30、低拉伸比为 2.7、蚀刻时间为 24 h 的 PLA/PBAT 薄膜具有最佳性能，其杨氏模量为 2.53 GPa，屈服强度为 51.9 MPa，伸长率为断裂率为 131.8%，水接触角为 131.8°。值得注意的是，经过表面处理的薄膜主要可以保持原有的力学性能。这项工作可以提供一种简便有效的方法来大规模制造具有良好机械性能和疏水性的绿色 PLA 基薄膜。2.7 的低拉伸比和 24 h 的蚀刻时间具有最佳性能，其杨氏模量为 2.53 GPa，屈服强度为 51.9 MPa，断裂伸长率为 131.8%，水接触角为 131.8°。值得注意的是，经过表面处理的薄膜主要可以保持原有的力学性能。这项工作可以提供一种简便有效的方法来大规模制造具有良好机械性能和疏水性的绿色 PLA 基薄膜。2.7 的低拉伸比和 24 h 的蚀刻时间具有最佳性能，其杨氏模量为 2.53 GPa，屈服强度为 51.9 MPa，断裂伸长率为 131.8%，水接触角为 131.8°。值得注意的是，经过表面处理的薄膜主要可以保持原有的力学性能。这项工作可以提供一种简便有效的方法来大规模制造具有良好机械性能和疏水性的绿色 PLA 基薄膜。