Orientational order in gravity dispersed clay colloids: A synchrotron x-ray scattering study of Na fluorohectorite suspensions
Orientational order in gravity dispersed clay colloids: A synchrotron x-ray scattering study of Na fluorohectorite suspensions
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DOI：
10.1103/physreve.64.061704
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发表时间：
2001-12-01
影响因子：
2.4
通讯作者：
Venkataraman, C
中科院分区：
文献类型：
--
作者：
DiMasi, E;Fossum, JO;Venkataraman, C
粘土颗粒在盐水溶液中的胶体悬浮液是研究板状颗粒之间相互作用的理想模型系统，这是由于易于随盐的浓度调节它们的静电排斥。许多get和sol结构是可能的，包括非线性液晶顺序，尽管到目前为止，在粘土胶体中只有后者的定性鉴定。我们提出了同步辐射X射线衍射重力分散溶液的钠氟锂蒙脱石，合成膨胀粘土，在一个大的NaCl浓度范围。我们使用的液体散射技术，使我们能够识别区域中的颗粒重新定向从水平到垂直排列的地层中共存的样品内的不同高度。我们确定了两个不同的凝胶区域，其特征在于取向各向异性和域大小的差异。我们的研究结果提供了直接的证据，为有序，以及独特的结构信息，颗粒形态和排列在每个胶体相。
Colloidal suspensions of clay particles in aqueous salt solutions make ideal model systems for the study of interactions between plate-shaped particles, due to the ease in tuning their electrostatic repulsion with the concentration of the salt. Numerous get and sol structures are possible, including nematic liquid crystalline order, although only qualitative identification of the latter in clay colloids has been available so far. We present synchrotron x-ray diffraction from gravity dispersed solutions of Na fluorohectorite, a synthetic swelling clay, over a large NaCl concentration range. Our use of liquid scattering techniques allows us to identify regions in which particles reorient from horizontal to vertical alignments in strata coexisting at different heights within the sample. We identify two distinct gel regions characterized by differences in orientational anisotropy and domain size. Our results provide direct evidence for nematic order, as well as unique structural information regarding particle morphology and alignment within each of the colloid phases.