Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge, United Kingdom, CB2 3QZ.
Langmuir. 2010 Jun 15;26(12):9269-75. doi: 10.1021/la100125v.
During drying, colloidal dispersions undergo processes such as solidification, cracking, and the draining of interstitial pores. Here we show that the solidification of polystyrene and silica dispersions, during directional drying, occurs in two separate stages. These correspond to the initial ordering and subsequent aggregation of the colloidal particles. Transitions between these stages are observed as changes in transparency and color that propagate as distinct fronts along the drying layer. The dynamics of these fronts are shown to arise from a balance between compressive capillary forces and the electrostatic and van der Waals forces described by DLVO theory. This suggests a simple method by which the maximum interparticle repulsion between particles can be measured through the optical inspection of the dynamics of a drying dispersion, under a microscope.
在干燥过程中，胶体分散体会经历诸如固化、开裂和内部孔隙排水等过程。在这里，我们表明，在定向干燥过程中，聚苯乙烯和二氧化硅分散体的固化分两个阶段发生。这对应于胶体颗粒的初始有序化和随后的聚集。在这些阶段之间的转变表现为透明度和颜色的变化，这些变化以沿着干燥层传播的不同前沿的形式出现。这些前沿的动力学表现为压缩毛细力与由 DLVO 理论描述的静电和范德华力之间的平衡。这表明了一种简单的方法，通过在显微镜下观察干燥分散体动力学，可以通过光学检查来测量颗粒之间的最大排斥力。
