An in-situ Observation on Initial Aggregation Process of Colloidal Particles near Three-Phase Contact Line of Air, Water and Vertical Substrate

The self-assembling process near the three-phase contact line of air, water and vertical substrate is widely used to produce various kinds of nanostructured materials and devices. We perform an in-situ observation on the self-assembling process in the vicinity of the three phase contact line. Three kinds of aggregations, i.e. particle--particle aggregation, particle--chain aggregation and chain--chain aggregation, in the initial stage of vertical deposition process are revealed by our experiments. It is found that the particle--particle aggregation and the particle--chain aggregation can be qualitatively explained by the theory of the capillary immersion force and mirror image force, while the chain--chain aggregation leaves an opening question for the further studies. The present study may provide more deep insight into the self-assembling process of colloidal particles.