Strain-Induced Orientation of Host Rings that Determines the Sliding of Guest Polymers and Plasticity of Glassy Polyrotaxane,ACS Macro Letters

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Strain-Induced Orientation of Host Rings that Determines the Sliding of Guest Polymers and Plasticity of Glassy Polyrotaxane
ACS Macro Letters ( IF 5.1 ) Pub Date : 2024-08-09 , DOI: 10.1021/acsmacrolett.4c00369
Kazuaki Kato _{1,

2} , Kohzo Ito ₁ , Taiki Hoshino _{2,

3,

4}

Affiliation

The unique motility of mechanically interlocked polymers enables their mechanical properties to profoundly transform. This property has been exploited less in glassy materials than in rubbery materials. This study demonstrated that in the glassy state the rings must orient before sliding and clarified the requisite structural changes by the synchrotron microbeam X-ray diffraction mapping of a ductile cyclodextrin (CD)-based glassy polyrotaxane. After inducing neck formation and propagation by uniaxial tension, the strain-localized area was scanned, elucidating how the CD orientation and its correlation distance change. As necking approaches and local strain increases, the CD rotational axis orients considerably in the tensile direction. Near the neck inflection point, polymer sliding triggers a sudden structural transformation, forming a phase-separated structure between the CDs and polymers that toughens the neck. This strain-induced orientation preceding sliding appears to facilitate sliding. In the rubbery state, host molecules can orient freely with the guest polymer orientation, but glassy materials must be designed to facilitate host orientation to enable guest sliding with minimum molecular friction.

中文翻译：

主环的应变诱导取向决定了客体聚合物的滑动和玻璃状聚轮烷的可塑性

机械互锁聚合物的独特运动性使其机械性能发生深刻变化。与橡胶材料相比，该特性在玻璃材料中的利用较少。这项研究表明，在玻璃态下，环在滑动之前必须定向，并通过基于延性环糊精 (CD) 的玻璃态聚轮烷的同步加速器微束 X 射线衍射图阐明了必要的结构变化。通过单轴张力诱导颈部形成和扩展后，扫描应变局部区域，阐明 CD 方向及其相关距离如何变化。随着颈缩的接近和局部应变的增加，CD 旋转轴在拉伸方向上显着定向。在颈部拐点附近，聚合物滑动会引发突然的结构转变，在碳点和聚合物之间形成相分离结构，从而使颈部变得坚韧。这种在滑动之前引起的应变定向似乎有利于滑动。在橡胶态下，主体分子可以随客体聚合物方向自由取向，但玻璃状材料必须设计为促进主体取向，以使客体以最小的分子摩擦滑动。

更新日期：2024-08-09

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