Colloidal Polarization of Yolk/Shell Particles by Reconfiguration of Inner Cores Responsive to an External Magnetic Field

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• 作者：Ayako Okada ; Daisuke Nagao ; Takuya Ueno ; Haruyuki Ishii ; Mikio Konno
• 刊名：Langmuir
• 出版年：2013
• 出版时间：July 16, 2013
• 年：2013
• 卷：29
• 期：28
• 页码：9004-9009
• 全文大小：369K
• 年卷期：v.29,no.28(July 16, 2013)
• ISSN：1520-5827

文摘

Yolk/shell particles, which were hollow silica particles containing a movable magnetic silica core (MSC), were prepared by removing a middle polystyrene layer from multilayered particles of MSC/polystyrene/silica shell with heat treatment followed by a slight etching with a basic solution. An ac electric field was applied to the suspension of the yolk/shell particles to form pearl chains (1D structure) of yolk/shell particles. Observation with an optical microscope showed that the MSCs in the silica compartment of the pearl chains had a zigzag structure under the electric field. An external magnetic field applied to the suspension could form a novel structure of doublet MSC in the shell compartment of the quasi-pearl chain structure. Application of a magnetic field was also performed for 2D hexagonally close-packed assemblies of the yolk/shell particles, which could two-dimensionally form a doublet structure of MSCs as if they were polarized in the compartment. Switching on/off the magnetic field successfully controlled the positional ordering of cores in the consolidated silica shell.