Seifert Julian, Günzing Damian, Webers Samira, Dulle Martin, Kruteva Margarita, Landers Joachim, Wende Heiko, Schmidt Annette M
Chemistry Department, Universität zu Köln, 50939 Köln, Germany.
Soft Matter. 2021 Aug 28;17(32):7565-7584. doi: 10.1039/d0sm02104k. Epub 2021 Aug 3.
The implementation of anisotropy to functional materials is a key step towards future smart materials. In this work, we evaluate the influence of preorientation and sample architecture on the strain-induced anisotropy in hybrid elastomers containing covalently attached elongated magnetic filler particles. Accordingly, silica coated spindle-type hematite nanoparticles are incorporated into poly(dimethylsiloxane)-based elastomers, and two types of composite architectures are compared: on the one hand a conventional architecture of filled, covalently crosslinked elastomers, and on the other hybrid elastomers that are crosslinked exclusively by covalent attachment of the polymer chains to the particle surface. By the application of external strain and with magnetic fields, the orientational order of the elongated nanoparticles can be manipulated, and we investigate the interplay between strain, magnetic order, and orientational order of the particles by combining 2D small angle X-ray scattering experiments under strain and fields with Mössbauer spectroscopy under similar conditions, and supplementary angular-dependent magnetization experiments. The converging information is used to quantify the order in these interesting materials, while establishing a direct link between the magnetic properties and the spatial orientation of the embedded magnetic nanoparticles.
在功能材料中实现各向异性是迈向未来智能材料的关键一步。在这项工作中，我们评估了预取向和样品结构对含有共价连接的细长磁性填料颗粒的混合弹性体中应变诱导各向异性的影响。相应地，将二氧化硅包覆的纺锤形赤铁矿纳米颗粒掺入聚二甲基硅氧烷基弹性体中，并比较了两种类型的复合结构：一方面是填充的、共价交联的弹性体的传统结构，另一方面是仅通过聚合物链与颗粒表面的共价连接而交联的混合弹性体。通过施加外部应变和磁场，可以操纵细长纳米颗粒的取向顺序，并且我们通过将应变和磁场下的二维小角X射线散射实验与类似条件下的穆斯堡尔谱相结合，以及补充的角度相关磁化实验，来研究颗粒的应变、磁序和取向序之间的相互作用。收敛的信息用于量化这些有趣材料中的有序度，同时在磁性特性与嵌入磁性纳米颗粒的空间取向之间建立直接联系。
