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The top-down approach is breaking down of a system into small components, while bottom-up is assembling sub-systems into larger system. [15] A bottom-up approach for nano-assembly is a primary research target for nano-fabrication because top down synthesis is expensive (requiring external work) and is not selective on very small length scales, but is currently the primary mode of industrial ...
Molecular self-assembly is a key concept in supramolecular chemistry. [6] [7] [8] This is because assembly of molecules in such systems is directed through non-covalent interactions (e.g., hydrogen bonding, metal coordination, hydrophobic forces, van der Waals forces, pi-stacking interactions, and/or electrostatic) as well as electromagnetic interactions.
Another illustrative example is the soft-template infiltration manufacturing technique developed by Nazanin Bassiri-Gharb at Georgia Institute of Technology. This is a bottom-up nanomanufacturing technique for the fabrication of ferroelectric, piezoelectrically-active nanotubes.
DNA nanotechnology, specifically, is an example of bottom-up molecular self-assembly, in which molecular components spontaneously organize into stable structures; the particular form of these structures is induced by the physical and chemical properties of the components selected by the designers. [19]
Two main approaches are used in nanotechnology. In the "bottom-up" approach, materials and devices are built from molecular components which assemble themselves chemically by principles of molecular recognition. [24] In the "top-down" approach, nano-objects are constructed from larger entities without atomic-level control. [25]
3D AFM topography image of multilayered palladium nanosheet on silicon wafer. [7]The most commonly used nanosheet synthesis methods use a bottom-up approach, e.g., pre-organization and polymerization at interfaces like Langmuir–Blodgett films, [8] solution phase synthesis and chemical vapor deposition (CVD). [9]
Building blocks are used for bottom-up modular assembly of molecular architectures: nano-particles, [2] [3] metal-organic frameworks, [4] organic molecular constructs, supra-molecular complexes. [5] Using building blocks ensures strict control of what a final compound or a (supra)molecular construct will be. [6]
A bottom-up approach synthesizes the nanowire by combining constituent adatoms. Most synthesis techniques use a bottom-up approach. Initial synthesis via either method may often be followed by a nanowire thermal treatment step, often involving a form of self-limiting oxidation, to fine tune the size and aspect ratio of the structures. [7] After ...