Hierarchical interfaces induce high dielectric permittivity in nanocomposites containing TiO2@BaTiO3 nanofibers.
Hierarchical interfaces induce high dielectric permittivity in nanocomposites containing TiO2@BaTiO3 nanofibers.
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DOI：
10.1039/c4nr00703d
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发表时间：
2014-05
期刊：
影响因子：
6.7
通讯作者：
Xin Zhang;Weiwei Chen;Jianjun Wang;Yang Shen;L. Gu;Yuanhua Lin;C. Nan
中科院分区：
文献类型：
--
作者：
Xin Zhang;Weiwei Chen;Jianjun Wang;Yang Shen;L. Gu;Yuanhua Lin;C. Nan
界面问题在纳米复合材料或纳米混合系统中是常见且关键的，因为界面面积在纳米尺度上是巨大的。在0-3维聚合物纳米复合材料中，纳米夹杂物（0维）嵌入在三维连接的聚合物基体中，在纳米夹杂物和聚合物基体之间的界面处的界面极化可以诱导增强的介电常数。在这方面的贡献，我们提出并证明，在确定聚合物纳米复合材料的介电极化的接口的面积的拓扑结构起着同样重要的作用。采用静电纺丝法制备了包覆BaTiO 3纳米粒子的TiO 2纳米纤维，并将其与聚偏氟乙烯（PVDF）熔融共混制备了聚合物纳米复合薄膜。因此，这些纳米复合材料实现了分级界面的调制。这些额外的界面内的TiO 2纳米纤维的限制导致由界面区域形成的网状结构。聚合物纳米复合材料的介电常数因此在11体积%的低填料负载下比PVDF基质提高了约300%。相场模拟研究表明，增强的介电常数可以归因于在二氧化钛纳米纤维内部的膨胀界面区域的极化增加。通过原位透射电子显微镜方法研究了TiO2@BaTiO3纳米纤维的瞬时电击穿，进一步揭示了纳米纤维的击穿行为随着绝缘BaTiO 3纳米颗粒的掺入而从金属性转变为金属性的显著特征。
Interface issues are common and crucial in nanocomposites or nanohybrid systems since the interface area is enormous on the nanoscale. In the 0-3 dimensional polymer nanocomposites, in which nano-inclusions (0-dimension) are embedded in a 3-dimensionally connected polymer matrix, enhanced dielectric permittivity could be induced by the interfacial polarization at the interfaces between the nano-inclusions and the polymer matrix. In this contribution, we propose and demonstrate that the topological structure of the interface plays an equally important role as the area of the interface in determining the dielectric polarization of polymer nanocomposites. TiO2 nanofibers embedded with BaTiO3 nanoparticles are prepared via electrospinning and then fused with polyvinyl difluoride (PVDF) into polymer nanocomposite films. Modulation of hierarchical interfaces is thus achieved for these nanocomposites. The confinement of these additional interfaces inside the TiO2 nanofibers leads to percolated networks formed by the interfacial regions. The dielectric permittivity of the polymer nanocomposites is thus enhanced by ∼300% over the PVDF matrix at a low filler loading of 11 vol%. A phase-field simulation study indicates that the enhanced dielectric permittivity could be attributed to the increased polarization in the percolated interfacial regions inside the TiO2 nanofibers. The instantaneous electrical breakdown of the TiO2@BaTiO3 nanofibers studied by the in situ transmission electron microscopy method further reveals the striking feature that the breakdown behavior of the nanofibers changes from semiconductive to metallic with the incorporation of insulating BaTiO3 nanoparticles.