Using Hierarchical Self-Assembly To Form Three-Dimensional Lattices of Spheres (original) (raw)
Related papers
Chemistry of Materials, 2002
The ability to fabricate self-assembled three-dimensional (3D) structures is potentially useful for the development of diffractive optical devices, micromechanical systems, and sensory elements. Recently, techniques such as two-photon absorption and multilayer photolithography have been successfully employed to produce 3D structures. 1-3 In addition, colloidal particles have also been used in conjunction with solgel techniques to self-assemble nano-or microspheres through gravity or pressure to form closely packed periodic structures. 4-7 However, these processes are generally time-consuming, do not allow selective introduction of defects, and are not applicable to a wide range of materials, and more importantly, there is little control over the lattice structure of the self-assembly (e.g., simple cubic or diamond). Structures of millimeter-scale self-assembled objects have recently been reported using elements individually functionalized in selective areas. [8][9][10][11][12][13][14][15] It is expected that selective functionalized elements are needed to realize controlled assembly of 3D structures. Herein, novel approaches toward selective functionalization of defined areas on spheres are described. In particular, a general protocol is described here to selectively functionalize micro-or nanospheres with molecules that can potentially direct the self-assembly of these spheres through H-bonding, electrostatic or hydrophilic-hydrophobic interaction, or chemical reaction. These self-assembling sites are introduced via chemical reaction on exposed areas of the spheres; alternatively, a metal layer, such as gold, can be first deposited on the sphere for attaching the desired functional moieties.
Two-Dimensional Self-Assembly of Spherical Particles Using a Liquid Mold and Its Drying Process
Langmuir, 2003
We developed a novel process to fabricate particle wires through self-assembly on hydrophilic regions of SAMs (self-assembled monolayer). A SAM of octadecyltrichlorosilane was formed on a silicon substrate and modified by UV irradiation to create a pattern of hydrophobic octadecyl and hydrophilic silanol groups. Ethanol or water containing particles (550 or 800 nm diameter) were dropped onto a patterned SAM. The solution was separated into two droplets with a liquid bridge between the droplets along the hydrophilic regions of a patterned SAM. The droplets and the liquid bridge were used as a mold for fabrication of a two-dimensional pattern of colloid crystals. Particle wire was formed between two droplets and colloid crystals such as an opal structure were formed at both ends of the particle wire after drying the solution. The particle wires constructed from a close-packed structure or non-close-packed structure, i.e., square lattice, were fabricated through self-assembly at room temperature using this method.
Millimeter-scale self-assembly and its applications
Pure and Applied Chemistry, 2003
Self-assembly is a concept familiar to chemists. In the molecular and nanoscale regimes, it is often used as a strategy in fabricating regular 3D structures-that is, crystals. Self-assembly of components with sizes in the µm-to-mm range is less familiar to chemists; this type of self-assembly may, however, become technologically important in the future. In this size range, self-assembly offers methods to form regular 3D structures from components too small or too numerous to be manipulated by other means, and methods to incorporate function into these structures; it also offers simplicity and economy.
Self-assembly of polymeric microspheres of complex internal structures
Nature Materials, 2004
Self-assembly can easily produce intricate structures that would be difficult to make by conventional fabrication means. Here, self-assembly is used to prepare multicomponent polymeric microspheres of arbitrary internal symmetries. Droplets of liquid prepolymers are printed onto a water-soluble hydrogel, and are allowed to spread and coalesce into composite patches. These patches are then immersed in an isodense liquid, which both compensates the force of gravity and dissolves the gel beneath the polymers. Subsequently, the patches fold into spheres whose internal structures are dictated by the arrangement of the droplets printed onto the surface. The spheres can be solidified either thermally or by ultraviolet radiation. We present a theoretical analysis of droplet spreading, coalescence and folding. Conditions for the stability of the folded microspheres are derived from linear stability analysis. The composite microbeads that we describe are likely to find uses in optics, colloidal self-assembly and controlled-delivery applications.
Shape-Programmed Self-Assembly of Bead Structures
Proceedings of the 40th Annual Conference of the Association of Computer Aided Design in Architecture (ACADIA)
This paper demonstrates the potential of a robust, low-cost approach to programmable matter using beads and string to achieve complex shapes with novel self-organizing and deformational properties.
MRS Proceedings, 2000
Monodispersed colloidal spheres with dimensions in the range of 100 nm to 10 μm can be used as building blocks to fabricate highly ordered 3D micro- and nanostructures. For example, they can be self-assembled into closely packed lattices, which can be subsequently used as templates to generate 3D porous structures. Here we present the recent progress in our group regarding this approach.
D011 Patterned self-assembly of fine particles on three-dimensional structures
Proceedings of International Conference on Leading Edge Manufacturing in 21st century : LEM21, 2013
This study aims to extend patterned self-assembly of fine particles on a flat substrate to that on curved surface such as cylinder. Firstly, wettability pattern was fabricated on a cylinder using contact printing, and then the cylinder was dipped in and drawn up from the suspension that contained nanometer particles. The proper conditions were made clear from the standpoints of the contact print, wettability pattern design and the dip-coating characteristics respectively.
Size Selective Assembly of Colloidal Particles on a Template by Directed Self-Assembly Technique
Langmuir, 2006
We report a simple and effective approach to organize micron-and submicron-sized particles in a size selective manner. This approach utilizes the template assisted directed self-assembly technique. A topographically patterned photoresist surface is fabricated and used to create an ordered array of colloidal particles from their aqueous suspensions. Assembly of particles on this template is then achieved by using a conventional spin coating technique. Feasibility of this technique to form a large area of patterned particle assemblies has been investigated. To arrange the particles on the template, the physical confinement offered by the surface topography must overcome a joint effect of centrifugal force and the hydrophobic nature of the photoresist surface. This concept has been extended to the size selective sorting of colloidal particles. The capability of this technique for sorting and organizing colloidal particles of a particular diameter from a mixture of microspheres is demonstrated.
Demonstration of three-dimensional microstructure self-assembly
1995
Self-assembly of three-dimensional microstructures using the surface tension force of molten solder to produce omtof-plane rotation is demonstrated. The generic nature of the technique is illustrated by reconfiguring structures formed in both Ni metal and single crystal Si. The structures do not have a hinge to constrain the rotation. This considerably simplifies fabrication and eliminates problems associated with the compatibility of a suitable hinge material. Details of the fabrication processes are given and results are presented for rotated structures. [139]