2 1 Introduction
is quite comfortable, as it does not require deeper thoughts about properties and
applications. The second definition is more restrictive. It says that nanomaterials
are ones with properties inherently depending on the small grain size. As nanomaterials usually are quite expensive, such a restrictive definition makes more
sense.
The main difference between nanotechnology and conventional technologies
is the “bottom-up” approach preferred in nanotechnology, whereas conventional
technologies usually prefer the “top-down” approach. The difference between
these two approaches is explained for example, using the example of powder production. In this context, chemical synthesis is typical of the “bottom-up” approach;
whereas, crushing and milling are techniques that may be classified as “top-down”
processes. Certainly, there are processes, which may be seen as “in between”. A
typical example is the defoliation of silicates or graphite to obtain graphene.
The expression “top-down” describes processes starting from large pieces of
material to produce the intended structure by mechanical or chemical methods.
As long as the structures are in a range of sizes accessible by mechanical tools or
photolithographic processes, top-down processes have an unmatched flexibility in
application. Figure 1.2 summarizes the basic features of top-down processes.
“Bottom-up” processes are, in general chemical processes starting from atoms
or molecules as building blocks to produce nanoparticles, nanotubes or nanorods,
thin films or layered structured. Using their dimensionality for classification, these
Figure 1.1 To understand and apply nanomaterials, besides knowledge on materials science,
a basic understanding of physics and chemistry is necessary. As many applications are
connected to biology and medicine; knowledge in these fields are also of advantage.
Physics
Chemistry
Materials science
Biology, medicine
Nanomaterials
Figure 1.2 Conventional goods are produced by top-down processes, which start from bulk
material. Using mechanical or chemical processes, the intended product is obtained.
Mechanical or
chemical processing
StarƟng
material
Final
product
is quite comfortable, as it does not require deeper thoughts about properties and
applications. The second definition is more restrictive. It says that nanomaterials
are ones with properties inherently depending on the small grain size. As nanomaterials usually are quite expensive, such a restrictive definition makes more
sense.
The main difference between nanotechnology and conventional technologies
is the “bottom-up” approach preferred in nanotechnology, whereas conventional
technologies usually prefer the “top-down” approach. The difference between
these two approaches is explained for example, using the example of powder production. In this context, chemical synthesis is typical of the “bottom-up” approach;
whereas, crushing and milling are techniques that may be classified as “top-down”
processes. Certainly, there are processes, which may be seen as “in between”. A
typical example is the defoliation of silicates or graphite to obtain graphene.
The expression “top-down” describes processes starting from large pieces of
material to produce the intended structure by mechanical or chemical methods.
As long as the structures are in a range of sizes accessible by mechanical tools or
photolithographic processes, top-down processes have an unmatched flexibility in
application. Figure 1.2 summarizes the basic features of top-down processes.
“Bottom-up” processes are, in general chemical processes starting from atoms
or molecules as building blocks to produce nanoparticles, nanotubes or nanorods,
thin films or layered structured. Using their dimensionality for classification, these
Figure 1.1 To understand and apply nanomaterials, besides knowledge on materials science,
a basic understanding of physics and chemistry is necessary. As many applications are
connected to biology and medicine; knowledge in these fields are also of advantage.
Physics
Chemistry
Materials science
Biology, medicine
Nanomaterials
Figure 1.2 Conventional goods are produced by top-down processes, which start from bulk
material. Using mechanical or chemical processes, the intended product is obtained.
Mechanical or
chemical processing
StarƟng
material
Final
product