and the Environment
Frequently Asked Questions*
1. What is nanotechnology?
2. What kinds of structures are made on the nanoscale?
3. How can materials be "smart"?
4. Is nanotechnology really something new?
5. How does nanotechnology relate to existing disciplines like chemistry or biology?
6. How can something small like nanotechnology be applied to big things?
7. Who does nanotechnology?
8. What are the essential items in the nanotechnologist's toolbox?
9. When can we expect nanotechnology to become big?
10. Nanotechnology sounds great! Are there any environmental implications?
*Prepared by Tina Masciangioli, AAAS Environmental Science & Technology Policy Fellow, U.S. EPA, National Center for Environmental Research with Barbara Karn, U.S. EPA, National Center for Environmental Research
What is nanotechnology? Top of page
Nanotechnology has three important aspects: size, structure, and resulting novel properties.
The size of nanotechnology is on the nanometer scale where one nanometer (nm) is10-9 meter (a mm or 10 Å) - the size of atoms and molecules It takes about 3-10 atoms to span the length of a nanometer. In comparison, the diameter of a human hair is about 20,000 nm wide and a smoke particle is about 1,000 nm in diameter.
Nanotechnology is not just about the size of looking at very small things, it is about structure, or how things are put together, arranged, or assembled. It is the ability to work - observe, manipulate, and build - at the atomic or molecular level.
Nanotechnology produces materials and systems that exhibit novel and significantly changed physical, chemical, and biological properties because of their size and structure. When a substance consists only of clusters of a few hundred atoms, the laws of quantum mechanics influence dramatic changes in its mechanical, optical, and electronic properties. These properties include improved catalysts2, tunable photoactivity3, and increased strength4.
2. What kinds of structures are made on the nanoscale? Top of page
Nanoscale structures are familiar to environmental scientists and engineers5. Nanometer sized colloidal dispersions of solids, liquids, and gases in liquids (sols, emulsions, and foams, respectively) and solids and liquids in gases (smokes and fogs, or aerosols) are commonly encountered in the environment. For instance, natural weathering of minerals such as iron oxides and silicates, and microorganisms such as bacteria and algae can produce colloids,. In the environment, colloids can be also be important in the fate, transformation, and transport of metals6,7, toxic organic compounds8,9, viruses10, and radionuclides11.
The structures of nanotechnology are important in how they are made and how their atoms are ordered. That is, a nanoparticle (a collection of tens to thousands of atoms measuring about 1-100 nanometers in diameter) is created atom by atom, and the size (and sometimes shape) of the particle is a controlled by experimental conditions. Nanocrystal is also used to describe these particles because the atoms within the particle are highly ordered or crystalline. A synthesized nanoparticle, however, is often called colloidal or a colloidal crystal because it is nanosized, and because it is typically dispersed or suspended in a stabilizing medium.
Nanoparticles can also be arranged or assembled12 into ordered layers, or nanolayers. Such self-assembly is due to forces such as hydrogen bonding, dipolar forces, hydrophilic ("water loving") or hydrophobic ("water hating") interactions, and surface tension, gravity, and other forces are involved in making such "self-assembly" happen. Many naturally occurring biological structures like membranes, vesicles, and deoxyribose nucleic acid (DNA) are formed by self-assembly. Repeating structures with a tailored periodicity are also important in applications of nanotechnology, like photonics and improved catalysts. Understanding and building nanostructures through self-assembly is at the core of creating nanotechnologies.13
Nanotubes, most notably the fullerene-like "chicken-wire" construction of carbon atoms (carbon nanotubes14 or CNTs), are another important group of nanoscale structures.15 CNTs are stronger than steel while at the same time very flexible and lightweight.16 In addition to the remarkable mechanical properties, nanotubes could replace copper as an electrical conductor or replace silicon as a semiconductor. CNTs also transport heat better than any other known material.17 Together, these characteristics make nanotubes useful for a variety of applications, including super-strong cables18, chemical sensors19, nano-wires and active components in electronic devices20, field emitters for flat-screen televisions21, charge storage for batteries22, "tips" for scanning probe microscopes23, or additives in nanofabricated materials4,24.
3. How can materials be "smart"? Top of page
"Smart" materials are materials that respond with a shape or other property change upon application of externally applied driving forces (electrical, magnetic, thermal). Often these materials are highly ordered with multi-functionality. Shape-memory alloys are smart materials that can be bent into different shapes and then returned to their original shape upon being exposed to heat or other stimuli. Smart materials for environmental treatment can both sense the presence of a pollutant and then catalytically destroy it.25
4. Is nanotechnology really something new? Top of page
Many things we are already familiar with are nanoscale and analogous to applications of nanotechnology. For instance, living organisms from bacteria to beetles rely on nanometer-sized protein machines that do everything from whipping flagella to flexing muscles. All biological cells are comprised of smart materials that self-assemble. Nanometer-sized carbon (carbon black) that improves the mechanical properties of tires, nanometer silver particles that initiate photographic film development, and nanometer particles that are the basis of catalysts critical to the petrochemical industry have contributed to commercial products for many years. However, all of the above examples of technologies are not considered nanotechnology because they do not involve specific atomic manipulations to achieve desired properties and functions of materials or products. Nanotechnology does involve purposeful atomic manipulations and structural assembly to achieve predetermined properties and functions.
5. How does nanotechnology relate to existing disciplines like chemistry or biology? Top of page
Nanotechnology overlaps significantly with many disciplines with chemistry, physics, and materials research are at the core of nanotechnology. These are the fields that discovered the atom and understood its inner workings, developed the science of combining them in precise structures, and developed tools with which these nanostructures are probed and visualized. Manipulation of atoms and nanostructures is what nanotechnology is all about.
Nanoparticles and other nanostructured materials are often synthesized using chemical methods. However, nanotechnology is fundamentally different from traditional chemistry because it deals with manipulation and physical control at the atomic level of chemicals. Synthesizing a chemical with nanotechnology could actually mean building it atom by atom. Traditional chemistry in contrast works on a bulk scale. Chemical syntheses typically result in poor yields of desired products with many unwanted by-products. Using nanotechnology to synthesize chemicals would result in 100% yield of the desired products and no by-products. It could also mean using a nanostructured catalyst in a traditional chemical reaction to improve the rate or yield of products.
For biologists, studying molecular-level structure and function is also nothing new. Applying nanotechnology, however, significantly alters the work of biologists. Traditional biology involves the study of living systems, ranging from bacteria to beetles to humans. All of these organisms rely on nanometer-sized protein machines (molecular motors) to do everything from whipping flagella to flexing muscles. An application of nanotechnology would be isolating one of these molecular motors from a living system and using it to construct a nanoscale device. A nanotechnology derived molecular motor might be fueled by sunlight and produce a rotational force that could pump minute volumes of fluids (e.g. pharmaceuticals) or open and close valves in nanomechanical devices.26
6. How can something small like nanotechnology be applied to big things? Top of page
Nanoscale powders and particles are now being used to enhance the properties of automobile parts. Other examples are the development of light-weight aluminum bodies for automobiles, brake systems for high-speed trains, quieter aircrafts, and insulation tiles for re-entry spacecrafts. Stronger, lighter materials made using nanoparticles will aid in energy efficiency and dematerializing manufactured products.
7. Who does nanotechnology? Top of page
Scientists and engineers in many different fields of study are involved in nanotechnology research and development. In the crosscutting area of nanoelectronics, most researchers represent the fields of chemistry and physics. Those involved in nano-biotechnology, however, come from more diverse backgrounds, from optical physics and pathology to chemistry and mechanical engineering. Environmental applications of nanotechnology are also carried out by a diverse group of researchers, including environmental engineers and chemists.
8. What are the essential items in the nanotechnologist's toolbox? Top of page
The scanning tunneling microsope (STM) and atomic force microscope (AFM) are essential items in the nanotechnologists toolbox and are key to the emergence of this new field of science and technology. Nanoscale science essentially began with the groundbreaking invention of the STM, for which Gerd Binnig and Heinrich Rohrer of IBM were awarded the Nobel Prize for Physics in 1986.
Traditional microscopy works by reflecting either light (in the case of optical microscopes) or an electron beam (in the case of electron microscopes) off a surface and onto a lens. AFM and STM use a cantilever (a nanoscale arm) to "read" the electronic properties of a surface directly. Scientists can use these techniques not only to see atoms but also to push and pull them into place.
A significant part of nanotech research also involves the creation of nanoscale patterns using electron-beam lithography. Unlike photolithography, the technique used to make microchips, electron-beam lithography is not constrained by the wavelength of light. Using a beam of electrons from a scanning electron microscope, researchers can etch details on a chip as fine as a few nanometers.
9. When can we expect nanotechnology to become big? Top of page
Nanotechnology has already shown great potential for applications in environmental protection. Nanostructured materials are being used in devices for pollution sensing, treatment and remediation. Applications for pollution prevention through environmentally benign synthesis and manufacturing are also being explored. In addition, nanostructured materials are being used in many manufactured products, especially in composite materials and fillers.
The importance of nanotechnology research is reflected in the President's FY03 budget, which names nanotechnology as one of just four national, interagency R&D priorities - the others being anti-terrorism research, information technology and global climate change. The government-wide funding for nanotechnology R&D for FY01 was approximately $422 million and is estimated to be $707 million for the president's proposed budget for FY03. Nanotechnology also has huge economic potential, with an estimated total worldwide market size of over $1 trillion annually in 10 to 15 years27 and some nanoparticle manufacturers already listed on the NASDAQ.
However, there is still a large amount of research that must be conducted at the fundamental level of science to understand nanoscale structures before we can expect nanoscale technologies to be created and commercialized on a large scale
10. Nanotechnology sounds great! Are there any environmental implications? Top of page
Nanotechnology is a revolutionary science and engineering approach that will no doubt affect the existing infrastructure of consumer goods, manufacturing methods, and materials usage. It has the potential to have major consequences - positive and negative -- on the environment.
Nanotechnology can be of benefit to environmental protection in applications such as reducing use of raw and manufactured materials (dematerialization), minimizing or eliminating the generation of wastes and effluents, and reducing toxics. The environment is also protected in applications that more effectively treat waste streams and remediate existing polluted sites.
At the same time, potentially harmful effects of nanotechnology may exist. These effects might relate to the nature of nanoparticles themselves, the characteristics of the products made from them, or the aspects of the manufacturing process involved. For instance, colloidal particles are involved in the fate, transformation, and transport of metals6,7, toxic organic compounds8,9, viruses10, and radionuclides11 in the environment.
It is also possible that nanotechnology and its products could lead to societal changes that influence transportation, urban development, information management, and other activities of our society that directly or indirectly effect the quality of the environment.27
Because nanotechnology is an emerging area, however, it is still very much possible to anticipate both the potential positive and negative impacts it might have on the environment and then act to enhance what is beneficial and prevent or minimize what is harmful.
References: Top of page
(1) Roco, M. C.; Williams, R. S.; Alivasatos, P., Eds. Nanotechnology Research Directions: IWGN Workshop Report, Vision for Nanotechnology R&D in the Next Decade; Kluwer Academic Publisher: Dordrecht, 1999.
(18) Thess, A.; Lee, R.; Nikolaev, P.; Dai, H.; Petit, P.; Robert, J.; Xu, C.; Lee, Y. H.; Kim, S. G.; Rinzler, A. G.; Colbert, D. T.; Scuseria, G. E.; Tomanek, D.; Fischer, J. E.; Smalley, R. E. Science 1996, 273, 483-487.