Using Hierarchical Self-Assembly To Form Three-Dimensional Lattices of Spheres

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• 作者：Hongkai Wu ; Venkat R. Thalladi ; Sue Whitesides ; and George M. Whitesides
• 刊名：Journal of the American Chemical Society
• 出版年：2002
• 出版时间：December 4, 2002
• 年：2002
• 卷：124
• 期：48
• 页码：14495 - 14502
• 全文大小：1108K
• 年卷期：v.124,no.48(December 4, 2002)
• ISSN：1520-5126

文摘

This paper describes an approach to the fabrication of three-dimensional (3-D) structures ofmillimeter-scale spherical beads having a range of lattices-tetragonal, cubic, and hexagonal-usinghierarchical self-assembly. The process has five steps: (i) metal-coated beads are packed in a rod-shapedcavity in an elastomeric polymer (poly(dimethylsiloxane), PDMS); (ii) the beads are embedded in a secondpolymer (PDMS or polyurethane, PU) using a procedure that leaves the parts of the beads in contact withthe PDMS exposed; (iii) the exposed areas of the beads are coated with a solder having a low meltingpoint; (iv) the polymer rods-with embedded beads and exposed solder drops-are suspended in anapproximately isodense medium (an aqueous solution of KBr) and allowed to self-assemble by capillaryinteractions between the drops of molten solder; and (v) the assembly is finished by several procedures,including removing the beads from the polymer matrix by dissolution, filling the voids left with anothermaterial, and dissolving the matrix. The confinement of the beads in regular structures in polymer rodsmakes it possible to generate self-assembled structures with a variety of 3-D lattices; the type of the latticeformed can be controlled by varying the size of the beads, and the size and shape of the cross-section ofthe rods.