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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.
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]
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 ...
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]
Nanomanufacturing refers to manufacturing processes of objects or material with dimensions between one and one hundred nanometers. [15] These processes results in nanotechnology, extremely small devices, structures, features, and systems that have applications in organic chemistry, molecular biology, aerospace engineering, physics, and beyond. [16]
The VLS mechanism circumvents this by introducing a catalytic liquid alloy phase which can rapidly adsorb a vapor to supersaturation levels, and from which crystal growth can subsequently occur from nucleated seeds at the liquid–solid interface. The physical characteristics of nanowires grown in this manner depend, in a controllable way, upon ...
Laser ablation synthesis in solution (LASiS) is a commonly used method for obtaining colloidal solution of nanoparticles in a variety of solvents. [ 1 ] [ 2 ] Nanoparticles (NPs,), are useful in chemistry, engineering and biochemistry due to their large surface-to-volume ratio that causes them to have unique physical properties. [ 3 ]