Laboratoire de Physique de la Matière Condensée et Nanostructures, Université de Lyon, Université Claude Bernard Lyon 1, CNRS, UMR 5586, Domaine Scientifique de la Doua, F-69622 Villeurbanne Cedex, France.
Langmuir. 2009 Oct 20;25(20):12048-55. doi: 10.1021/la901244v.
Using a fluorescence recovery after photobleaching (FRAP) technique, we present measurements of probe diffusion in a colloidal glass-a Laponite suspension. By varying the probe size over 2 orders of magnitude, as well as the concentration of the colloidal glass, we evidence and quantify the deviations of the probe diffusivity from the bulk Stokes-Einstein expectations. These experiments suggest that the probe diffusion in the dynamically arrested Laponite structure is mainly controlled by the ratio between the probe size and the typical clay platelets interdistance. Comparing with a simple hindered diffusion mechanism, the reduction of tracer diffusion is discussed in terms of the hydrodynamic interaction of the probe with the Laponite structure. Finally, these results can be interpreted in terms of a scale dependent viscosity of the colloidal glass.
我们使用荧光恢复后漂白（FRAP）技术，对胶体玻璃-拉彭特悬浮液中的探针扩散进行了测量。通过在两个数量级上改变探针的尺寸，以及胶体玻璃的浓度，我们证明并量化了探针扩散率与体 Stokes-Einstein 预期的偏差。这些实验表明，探针在动态捕获的拉彭特结构中的扩散主要由探针尺寸与典型的粘土薄片间隔之比控制。与简单的受阻扩散机制相比，通过探针与拉彭特结构的流体动力学相互作用，讨论了示踪剂扩散的减少。最后，可以根据胶体玻璃的尺度相关粘度来解释这些结果。
