15
than one answer to that question of which the most obvious is
that of surface area. Almost all properties of the thin layer of atoms
that lie in the surface or interface of things behave in a different
way than those in the interior. Surfaces, you could say, have their
own properties. We experience this in their propensity to corrode,
to stick (or not stick) to things, or to release electrons in plasma
displays. But most of the useful properties—stiffness, strength,
thermal and electrical conductivities, magnetism—come from the
inside of atoms. At the familiar macroscale, the fraction of atoms
that lie in the surface is minuscule. At the micron scale it is still
tiny. But approach the nanoscale and it takes off (see Figure 1.14).
The combination of small scale and a large fraction of “surface”
atoms gives a property set that can be very different from that of the
bulk. It is only now being unveiled. Nanomaterials have different
mechanical, thermal, electrical, magnetic, optical, and, above all,
chemical properties than those of the bulk. They can offer strong,
wear-resistant coatings; they can change the ways in which heat
and electricity are conducted; they have the ability, through their
electrical and magnetic behavior, to store information and via their
chemical behavior to catalyze chemical reactions, distribute drugs
in the human body, and much more.
Some of this “science fiction” is already real. Much more is a
promise, but one in which considerable confidence can be placed.
As with most major innovations, there are two principle obstacles
to be overcome. The first: to develop a sufficiently deep understanding of behavior to establish both the good and the bad, the benefits
and the hazards, of the nanoscale. The second is that of economics.
Nanomaterials are expensive and will remain so, at least for some
time. Finding ways to cushion the transition to economic viability
needs thought.
Further readiNg
R. Freitas Jr., in Nanomedicine, Vol. I: Basic capabilities, Landes Bioscience,
1999.
R. P. Feynman, There’s plenty of room at the bottom, Engineering and
Science (California Institute of Technology), p. 22, Feb. 1960.
N. Taniguchi, Proc. International Conf., Prod. Eng. Tokyo, Part II, Japan
Society of Precision Engineering, 1974.
K. Eric Drexler, Molecular engineering: An approach to the development
of general capabilities for molecular manipulation, Proc. National
Academy of Sciences, p. 5275, Sept. 1981.
K. Eric Drexler, Engines of creation: The coming era of nanotechnology,
Anchor Press/Doubleday, 1986.
Figure 1.14
The fraction of atoms that lie in the surface
or internal interfaces of a nanoscale or
nanostructured material, expressed as a
percentage (%).
100
10
1
0.1
Fraction of surface atoms (%)
10
–2
10
–3
10
–4
1
10
Dimension in nanometers
10
2
10
3
10
4
10
5
10
6
1 mm
1 nm
1 µm
Further Reading
than one answer to that question of which the most obvious is
that of surface area. Almost all properties of the thin layer of atoms
that lie in the surface or interface of things behave in a different
way than those in the interior. Surfaces, you could say, have their
own properties. We experience this in their propensity to corrode,
to stick (or not stick) to things, or to release electrons in plasma
displays. But most of the useful properties—stiffness, strength,
thermal and electrical conductivities, magnetism—come from the
inside of atoms. At the familiar macroscale, the fraction of atoms
that lie in the surface is minuscule. At the micron scale it is still
tiny. But approach the nanoscale and it takes off (see Figure 1.14).
The combination of small scale and a large fraction of “surface”
atoms gives a property set that can be very different from that of the
bulk. It is only now being unveiled. Nanomaterials have different
mechanical, thermal, electrical, magnetic, optical, and, above all,
chemical properties than those of the bulk. They can offer strong,
wear-resistant coatings; they can change the ways in which heat
and electricity are conducted; they have the ability, through their
electrical and magnetic behavior, to store information and via their
chemical behavior to catalyze chemical reactions, distribute drugs
in the human body, and much more.
Some of this “science fiction” is already real. Much more is a
promise, but one in which considerable confidence can be placed.
As with most major innovations, there are two principle obstacles
to be overcome. The first: to develop a sufficiently deep understanding of behavior to establish both the good and the bad, the benefits
and the hazards, of the nanoscale. The second is that of economics.
Nanomaterials are expensive and will remain so, at least for some
time. Finding ways to cushion the transition to economic viability
needs thought.
Further readiNg
R. Freitas Jr., in Nanomedicine, Vol. I: Basic capabilities, Landes Bioscience,
1999.
R. P. Feynman, There’s plenty of room at the bottom, Engineering and
Science (California Institute of Technology), p. 22, Feb. 1960.
N. Taniguchi, Proc. International Conf., Prod. Eng. Tokyo, Part II, Japan
Society of Precision Engineering, 1974.
K. Eric Drexler, Molecular engineering: An approach to the development
of general capabilities for molecular manipulation, Proc. National
Academy of Sciences, p. 5275, Sept. 1981.
K. Eric Drexler, Engines of creation: The coming era of nanotechnology,
Anchor Press/Doubleday, 1986.
Figure 1.14
The fraction of atoms that lie in the surface
or internal interfaces of a nanoscale or
nanostructured material, expressed as a
percentage (%).
100
10
1
0.1
Fraction of surface atoms (%)
10
–2
10
–3
10
–4
1
10
Dimension in nanometers
10
2
10
3
10
4
10
5
10
6
1 mm
1 nm
1 µm
Further Reading