Capillary Rise and Flow of Complex Liquids in Nanopores

我们建议研究复杂液体在单块、多孔石英玻璃和多孔硅(平均孔径d=10 nm)中的流动，作为液体构件的大小和形状以及外加剪切速率的函数。特别是，我们想要比较在膜流动装置中测量的流量和关于自发吸胀的测量，即毛细管力驱动的毛细上升。虽然流动装置的测量将使我们能够确定纳米受限液体的粘度，但毛细上升的填充过程不仅取决于粘性阻力，还取决于作用在纳米孔中的毛细压力。为了改变液体的复杂性，我们建议测量由链状(正构烷烃)、棒状和盘状(液晶)分子组成的液体-所有这些分子的分子尺寸都在纳米孔直径的数量级上。这项实验研究将阐明这样一个问题，即在多大程度上，连续统型的宏观流体行为在纳米尺度下是有效的。

We propose to study the flow of complex liquids in monolithic, porous silica glasses and porous silicon (mean pore diameter d = 10nm) as a function of the size and shape of the building blocks of the liquids and the applied shear rates. In particular, we would like to compare flow rate measurements taken in a membrane flow apparatus with measurements on the spontaneous imbibition, that is the capillary rise in the pores driven by capillary forces. Whereas the flow apparatus measurements will allow us to determine the viscosities of the nanoconfined liquids, the filling process of the capillary rise crucially depends not only on the viscous drag but also on the capillary pressure acting in the nanopores. In order to vary the complexity of the liquids we suggest to measure liquids built out of chain-like (n-alkanes), rod-like and disc-like (liquid crystals) molecules - all of them with molecular sizes on the order of the diameter of the nanopores. The experimental study will shed light on the question to what extend continuum-like, macroscopic fluid behavior is valid down to nano-scopic lenght scales.