Hemmen Henrik, Ringdal Nils I, De Azevedo Eduardo N, Engelsberg Mario, Hansen Elisabeth L, Méheust Yves, Fossum Jon O, Knudsen Kenneth D
Department of Physics, Norwegian University of Science and Technology, Hoegskoleringen 5, N-7491, Trondheim, Norway.
Langmuir. 2009 Nov 3;25(21):12507-15. doi: 10.1021/la901784k.
Colloidal suspensions of Na-fluorohectorite synthetic clay platelets in saline water exhibit coexisting isotropic and nematic phases, due to gravitational separation of the polydisperse particles. We study the ordering of the platelets at the interfaces between various coexisting phases. Four different experimental techniques are employed: visual observation of birefringence, synchrotron wide angle and small-angle X-ray scattering, and magnetic resonance imaging. We find that at the narrow isotropic sol-nematic sol interface the platelets are lying horizontally, i.e. with their mean platelet normal along the vertical direction. The experiments indicate that the platelets align homeotropically both at the isotropic sol-nematic sol interface and at the nematic sol-wall interface. We further investigate the complex alignment effect of a horizontally applied magnetic field in the nematic sol, and we compare it with the adjacent nematic gel.
由于多分散颗粒的重力分离，氟化钠锂皂石合成粘土薄片在盐水中的胶体悬浮液呈现各向同性相和向列相共存的状态。我们研究了共存相中不同相界面处薄片的排列情况。采用了四种不同的实验技术：双折射的视觉观察、同步加速器广角和小角X射线散射以及磁共振成像。我们发现，在狭窄的各向同性溶胶 - 向列溶胶界面处，薄片呈水平排列，即其平均薄片法线沿垂直方向。实验表明，薄片在各向同性溶胶 - 向列溶胶界面和向列溶胶 - 壁界面处均垂直排列。我们进一步研究了向列溶胶中水平施加磁场的复杂排列效应，并将其与相邻的向列凝胶进行了比较。
