van der Beek D, Reich H, van der Schoot P, Dijkstra M, Schilling T, Vink R, Schmidt M, van Roij R, Lekkerkerker H
Van't Hoff Laboratory for Physical and Colloid Chemistry, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
Phys Rev Lett. 2006 Aug 25;97(8):087801. doi: 10.1103/PhysRevLett.97.087801.
We study interfacial phenomena in a colloidal dispersion of sterically stabilized gibbsite platelets, exhibiting coexisting isotropic and nematic phases separated by a sharp horizontal interface. The nematic phase wets a vertical glass wall and polarized light micrographs reveal homeotropic surface anchoring both at the free isotropic-nematic interface and at the wall. On the basis of complete wetting of the wall by the nematic phase, as found in our density functional calculations and computer simulations, we analyze the balance between Frank elasticity and surface anchoring near the contact line. Because of weak surface anchoring, the director field in the capillary rise region is uniform. From the measured rise (6 microm) of the meniscus at the wall we determine the isotropic-nematic surface tension to be 3 nN/m, in quantitative agreement with our theoretical and simulation results.
我们研究了空间稳定的三水铝石片状颗粒胶体分散体系中的界面现象，该体系呈现出由清晰的水平界面分隔的共存各向同性相和向列相。向列相浸润垂直的玻璃壁，偏光显微镜图像显示在自由的各向同性 - 向列相界面以及壁处均存在垂直排列的表面锚定。基于我们的密度泛函计算和计算机模拟中发现的向列相对壁的完全浸润，我们分析了在接触线附近弗兰克弹性和表面锚定之间的平衡。由于表面锚定较弱，毛细管上升区域的指向矢场是均匀的。根据在壁处测得的弯月面上升高度（6微米），我们确定各向同性 - 向列相表面张力为3 nN/m，这与我们的理论和模拟结果在定量上相符。
