Interfacial Shish-Kebabs Lengthened by Coupling Effect of In Situ Flexible Nanofibrils and Intense Shear Flow: Achieving Hierarchy To Conquer the Conflicts between Strength and Toughness of Polylactide
Interfacial Shish-Kebabs Lengthened by Coupling Effect of In Situ Flexible Nanofibrils and Intense Shear Flow: Achieving Hierarchy To Conquer the Conflicts between Strength and Toughness of Polylactide
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原位柔性纳米纤丝与强剪切流耦合作用延长界面串丝：实现层次结构以克服聚丙交酯的强度和韧性之间的冲突
DOI：
10.1021/acsami.7b00479
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发表时间：
2017
影响因子：
9.5
通讯作者：
Li Zhong-Ming
中科院分区：
文献类型：
--
作者：
Zhou Sheng-Yang;Niu Ben;Xie Xu-Long;Ji Xu;Zhong Gan-Ji;Hsiao Benjamin S.;Li Zhong-Ming
如何克服聚乳酸（PLA）的强度和韧性之间的矛盾，一直是学术界和工业界面临的挑战。在目前的工作中，一个独特的层次结构的柔性聚（己二酸丁二醇酯-共-对苯二甲酸酯）（PBAT）原位纳米原纤维与丰富的PLA shish-kebabs作为一个强大的积木集成被公开，并表示其能力，以克服这一困境。与纯PLA（61.5 MPa、4.3 KJ/m2和6.2%）相比，拉伸强度、冲击强度和断裂伸长率可以分别达到91.2 MPa、14.9 KJ/m2和15.7%。通过对PLA/PBAT体系相（晶）态和分子链行为的研究，明确了PBAT柔性相和剪切流耦合作用促进该结构形成的机理。PBAT的分散相将更倾向于以纤维形式存在于PLA基质中，这得益于低界面张力。有趣的是，这种具有大比表面积的相形态显著改变了PLA的结晶行为，一旦引入强烈的剪切流（103 s-1），原位剪切形成的PBAT纳米原纤将显示出与剪切流对PLA结晶的强烈耦合作用：它们不仅可以在PLA的界面处诱导出丰富的串状聚乳酸，串状聚乳酸具有延长的串状聚乳酸和更密集排列的串状聚乳酸，而且通过其PBAT相的滞后松弛进一步延缓PLA链的松弛，从而有效地防止了已形成的shish的坍塌。具有重要意义的是这种由柔性纳米纤维（PBAT）和刚性串晶（PLA）组成的特殊层次结构，它为聚合物材料的同时增强和韧性提供了重要指导。
The challenge of hitherto elaborating a feasible pathway to overcome the conflicts between strength and toughness of polylactide (PLA) still remains among academia and industry. In the current work, a unique hierarchal structure of flexible poly(butylene adipate-co-terephthalate) (PBAT) in situ nanofibrils integrating with abundant PLA shish-kebabs as a strong building block was disclosed and expresses its capability to conquer this dilemma. Substantially simultaneous enhancement on tensile strength, impact strength, and elongation at break could be achieved up to 91.2 MPa, 14.9 KJ/m2, and 15.7%, respectively, compared with pure PLA (61.5 MPa, 4.3 KJ/m2, and 6.2%). Through investigating the phase (and crystalline) morphology and molecular chain behavior in the PLA/PBAT system, the formation mechanism of this structure facilitated by a coupling effect of PBAT flexible phase and shear flow was definitely elucidated. The dispersed phase of PBAT would be more inclined to existing as a fibrillar form within the PLA matrix benefiting from low interfacial tension. Interestingly, this phase morphology with large specific surface area changes the crystallization behavior of PLA significantly, once introducing an intense shear flow (∼103s–1), in situ shear-formed nanofibrils of PBAT would show strong coupling effect with shear flow on PLA crystallization: they can not only induce abundant shish-kebabs of PLA at its interfaces, which possesses lengthened shish and more densely arranged kebabs, but also further retard the relaxation of PLA chains through hysteretic relaxation of its PBAT phase, which can effectively prevent the collapse of established shish. Of immense significance is this particular hierarchical-architecture composed by flexible nanofibers (PBAT) and rigid shish-kebabs (PLA), which provides significant guidance for the simultaneous reinforcement and toughness of polymer materials.