Uniaxial Stretching-Induced Alignment of Carbon Nanotubes in Cross-Linked Elastomer Enabled by Dynamic Cross-Link Reshuffling,ACS Macro Letters

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Uniaxial Stretching-Induced Alignment of Carbon Nanotubes in Cross-Linked Elastomer Enabled by Dynamic Cross-Link Reshuffling
ACS Macro Letters ( IF 5.1 ) Pub Date : 2019-11-29 , DOI: 10.1021/acsmacrolett.9b00836
Zhenghai Tang ₁ , Qingyi Huang ₁ , Yingjun Liu ₁ , Yi Chen ₁ , Baochun Guo ₁ , Liqun Zhang ₂

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The fascinating properties of carbon nanotubes (CNTs) make them highly promising in fabricating polymer composites. Yet, the property enhancements of polymer/CNTs composites remain far behind the theoretical predictions. A critical issue to resolve this dilemma is to align CNTs in polymer matrices. Thus far, the state of art approaches to create CNT alignment either require complicated preparation processes and specific apparatuses, or is limited to thermoplastic polymers. Here, inspired by the network rearrangement ability of vitrimer in the solid state, we bring forth a facile methodology to align CNT in covalently cross-linked polymers by uniaxially stretching dynamic. Specifically, dynamic boronic ester bond-cross-linked epoxidized natural rubber/CNTs vitrimer composites with randomly dispersed CNTs are prepared, which are able to rearrange the network topologies and release stress at elevated temperatures through boronic ester transesterifications. The alignment of CNTs is performed by the uniaxial stretching of the composites and subsequent cross-link reshuffling at elevated temperatures, which results in anisotropic composites with remarkably enhanced mechanical properties and reduced electrical conductivity along the stretching direction. Furthermore, the mechanical properties of the composites can be readily adjusted by changing the applied strain, relaxation time and temperature due to the modulated CNT alignment degree. With this example, we envisage that this work offers a conceptual and facile approach to align anisotropic fillers in covalently cross-linked polymers.

中文翻译：

由动态交联重排实现的交联弹性体中碳纳米管的单轴拉伸诱导排列

碳纳米管 (CNT) 的迷人特性使其在制造聚合物复合材料方面非常有前景。然而，聚合物/碳纳米管复合材料的性能增强仍远远落后于理论预测。解决这一困境的一个关键问题是在聚合物基质中排列 CNT。到目前为止，创建 CNT 排列的现有技术方法要么需要复杂的制备过程和特定设备，要么仅限于热塑性聚合物。在这里，受固态玻璃体的网络重排能力的启发，我们提出了一种通过单轴拉伸动力学在共价交联聚合物中排列 CNT 的简便方法。具体而言，制备了碳纳米管随机分散的动态硼酸酯键交联环氧化天然橡胶/碳纳米管 vitrimer 复合材料，它们能够重新排列网络拓扑并通过硼酸酯酯交换在高温下释放应力。碳纳米管的排列是通过复合材料的单轴拉伸和随后在高温下的交联重排来进行的，这导致各向异性复合材料具有显着提高的机械性能和沿拉伸方向降低的电导率。此外，由于调制的 CNT 取向度，可以通过改变施加的应变、弛豫时间和温度来轻松调节复合材料的机械性能。通过这个例子，我们设想这项工作提供了一种概念性和简便的方法来排列共价交联聚合物中的各向异性填料。

更新日期：2019-11-30

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