Richards Jeffrey J, Wagner Norman J, Butler Paul D
NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
Department of Chemical and Biomolecular Engineering, Center for Neutron Science, University of Delaware, Newark, Delaware 98195, USA.
Rev Sci Instrum. 2017 Oct;88(10):105115. doi: 10.1063/1.4986770.
In situ measurements are an increasingly important tool to inform the complex relationship between nanoscale properties and macroscopic material measurements. Knowledge of these phenomena can be used to develop new materials to meet the performance demands of next generation technologies. Conductive complex fluids have emerged as an area of research where the electrical and mechanical properties are key design parameters. To study the relationship between microstructure, conductivity, and rheology, we have developed a small angle neutron scattering (SANS) compatible Couette rheological geometry capable of making impedance spectroscopy measurements under continuous shear. We have also mounted this geometry on a commercial strain controlled rheometer with a modified forced convection oven. In this manuscript, we introduce the simultaneous measurement of impedance spectroscopy, rheological properties and SANS data. We describe the validation of this dielectric RheoSANS instrument and demonstrate its operation using two systems-an ion gel comprising Pluronic® surfactant and ionic liquid, ethyl-ammonium nitrate, and poly(3-hexylthiophene) organogel prepared in a mixture of hexadecane and dichlorobenzene. In both systems, we use this new measurement capability to study the microstructural state of these materials under two different protocols. By monitoring their dielectric rheology at the same time as the SANS measurement, we demonstrate the capacity to directly probe structure-property relationships inherent to the macroscopic material response.
原位测量是一种日益重要的工具，用于揭示纳米级特性与宏观材料测量之间的复杂关系。对这些现象的了解可用于开发新材料，以满足下一代技术的性能需求。导电复合流体已成为一个研究领域，其中电学和力学性能是关键设计参数。为了研究微观结构、电导率和流变学之间的关系，我们开发了一种与小角中子散射（SANS）兼容的库埃特流变几何结构，能够在连续剪切下进行阻抗谱测量。我们还将这种几何结构安装在一台带有改进型强制对流烘箱的商用应变控制流变仪上。在本论文中，我们介绍了阻抗谱、流变性能和SANS数据的同步测量。我们描述了这种介电流变体散射仪的验证，并使用两个系统展示了其操作——一种由普朗尼克®表面活性剂和离子液体硝酸乙铵组成的离子凝胶，以及在十六烷和二氯苯的混合物中制备的聚（3-己基噻吩）有机凝胶。在这两个系统中，我们利用这种新的测量能力，在两种不同的实验方案下研究这些材料的微观结构状态。通过在进行SANS测量的同时监测它们的介电流变学，我们展示了直接探究宏观材料响应中固有的结构-性能关系的能力。
