Sedimentation Pattern of Polymer Colloidal Dispersions in the External Fields

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In this project, the convectional, sedimentation and drying dissipative patterns during the course of drying polymer colloidal dispersions and others were studied intensively Main results obtained are summarized as following:(1) The broad ring-like sedimentation patterns were formed on a cover glass, a watch glass and a glass dish, which demonstrates the important role of the convectional flow of water and colloidal spheres. The sedimentary spheres changed their semi-equilibrium position floating over the substrates by the balancing between the outside and/or upward convectional flow and inner ward and/or downward sedimentation.(2) Macroscopic (broad rings and spoke-like lines) and microscopic (fine multiple spoke lines, sting-like, star-like patterns, etc) drying patterns formed.(3) Convectional patterns of Chinese black ink and aqueous suspensions of poly (methyl methacrylate), PMMA spheres have been studied in detail at the elevated and the room temperatures, respectively. Broad ring, spoke line ("Terada cells") and the circulating cell structures were observed, for the first time, on the substrates.(4) Patterns in a flow field and theoretical discussion including computational simulation on the convectional, sedimentation and drying dissipative patterns are still open for further study.