What is self-assembled monolayer in nanotechnology?
A Self-Assembled Monolayer (SAM) is a one molecule thick layer of material that bonds to a surface in an ordered way as a result of physical or chemical forces during a deposition process. Silanes can form SAMs by solution or vapor phase deposition processes. Most commonly, chlorosilanes or alkoxysilanes are used.
How do you create a self-assembled monolayer?
Figure 1 Self-assembled monolayers are formed by simply immersing a substrate into a solution of the surface-active material. The driving force for the spontaneous formation of the 2D assembly includes chemical bond formation of molecules with the surface and intermolecular interactions.
What are self-assembled monolayers used for?
SAMs can serve as models for studying membrane properties of cells and organelles and cell attachment on surfaces. SAMs can also be used to modify the surface properties of electrodes for electrochemistry, general electronics, and various NEMS and MEMS.
What are self-assembled materials?
Self-assembly is the process in which a system’s components—be it molecules, polymers, colloids, or macroscopic particles—organize into ordered and/or functional structures or patterns as a consequence of specific, local interactions among the components themselves, without external direction.
How thick are self assembled monolayers?
SAMs as Components of Nanoscience and Nanotechnology. SAMs are themselves nanostructures with a number of useful properties (Figure 1). For example, the thickness of a SAM is typically 1−3 nm; they are the most elementary form of a nanometer-scale organic thin-film material.
How does self-assembly work?
Self-assembly is a process in which a disordered system of pre-existing components forms an organized structure or pattern as a consequence of specific, local interactions among the components themselves, without external direction.
How thick are self-assembled monolayers?
Is self-assembly reversible?
Self-assembly in the classic sense can be defined as the spontaneous and reversible organization of molecular units into ordered structures by non-covalent interactions. In such a way, highly organized covalent molecules may be formed in a specific manner.
What are the two types of self-assembly?
There are two types of self-assembly, intramolecular self-assembly and intermolecular self-assembly. Most often the term molecular self-assembly refers to intermolecular self-assembly, while the intramolecular analog is more commonly called folding.
What is meant by monolayer?
: a single continuous layer or film that is one cell, molecule, or atom in thickness.
Why is self-assembly important?
Self-assembly has the potential to provide the basis for a new form of molecular synthesis. Classical, covalent synthesis now is so accomplished and successful as an art and a technology that it can make most target molecules.
What is supramolecular self-assembly?
A supramolecular assembly is a complex of molecules held together by noncovalent bonds. Thus they allow access to nanoscale objects using a bottom-up approach in far fewer steps than a single molecule of similar dimensions. The process by which a supramolecular assembly forms is called molecular self-assembly.
How are self assembled monolayers of organic molecules formed?
Self-assembled monolayer. Self-assembled monolayers ( SAM) of organic molecules are molecular assemblies formed spontaneously on surfaces by adsorption and are organized into more or less large ordered domains. In some cases molecules that form the monolayer do not interact strongly with the substrate.
Why are self assembled monolayers of noble metals special?
Self-assembled monolayers of thiolates on noble metals are a special case because the metal-metal bonds become reversible after the formation of the thiolate-metal complex. This reversibility is what gives rise to vacancy islands and it is why SAMs of alkanethiolates can be thermally desorbed and undergo exchange with free thiols.
How are SAMs formed in a self assembled monolayer?
SAMs are created by the chemisorption of “head groups” onto a substrate from either the vapor or liquid phase followed by a slow organization of “tail groups”.
Which is the best description of a monolayer?
Monolayer. A monolayer is a single, closely packed layer of atoms, molecules, or cells. In some cases it is referred to as a self-assembled monolayer. Monolayers of layered crystals like graphene and molybdenum disulfide are generally called 2D materials .