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Pulickel M. Ajayan is the Benjamin M. and Mary Greenwood Anderson Professor in Engineering at Rice University.In 1992, Dr. Ajayan discovered the first method to make macro-scale quantities of nanotubes. Dr. Ajayan is one of the pioneering researchers in the field of carbon nanotubes, and has done nanotechnology research in the U.S., Japan, France and Germany. Dr. Ajayan has taught several undergraduate courses in nanotechnology, and has won numerous awards and honors for his work. He currently serves on the Scientific Advisory Board of the Nanotech Company, LLC, and Nanotechnology.com. He is the 2006 recipient of the prestigious MRS Prize, considered one of the highest honors in Materials Science.

Dr. Ajayan's pioneering research should directly result in a thriving nanotube industry within a decade.

Pulickel M. Ajayan

Tell us about yourself. What is your background, and on what projects are you currently working?

I am currently a Professor of Materials Engineering at Rensselaer Polytechnic Institute but will be joining Rice University this fall. I am originally from southern India. I received a PhD in materials science and engineering from Northwestern University in 1989. In those days, nanotechnology was not an established field, so although I did my research in nanoparticles using electron microscopy, it was always referred to as small particles. I spent several years in Japan working as a Postdoc for NEC on nanoparticles. In Japan I began studying carbon nanotubes which were new at that time. I have done extensive research on nanotubes, and for the past decade I have been working at Rensselaer on the properties of nanotubes.

Tell us about the Carbon Nanotube Research Group.

This group was created in 1998 here at Rensselaer. The focus of this group is to engineer carbon nanotube structures so that they can be made into a variety of useful applications. For instance, we have examined using carbon nanotubes as interconnects in computers. We have explored the possibility of using nanotubes as cooling elements in electronics. We also have some unusual projects on creating biomimetic systems using nanotubes, and we are researching using nanotubes in polymer composites.

Researchers have been frustrated by the difficulty of producing nanotubes with uniform properties. Has your research laboratory been able to produce such uniform tubes?

Inexpensively creating large quantities of nanotubes with uniform properties is in many respects that holy grail of nanotube research. The varying electrical properties of nanotubes hampers our ability to derive useful applications from them. It is currently quite difficult to produce nanotubes with uniform structures and properties. So we are trying to use ordered aggregates (e.g. bundles) of nanotubes with varying properties to make improved products.

Can your lab produce large quantities of pure nanotubes?

Since we are a laboratory, we are not equipped to produce large quantities of materials. However, certain corporations are producing large quantities of nanotubes. Japanese corporations are producing 200 tons of multi-walled nanotubes. Even with single-walled nanotubes, which are much harder to make, there is promising research suggesting that kilogram quantities should soon become affordable. But demand currently exceeds supply by a wide margin, so they are expensive.

What will be the first commercial applications to incorporate nanotubes into their structures? When will these applications emerge?

We recently wrote a chapter of a book (edited by Dresselhaus and Jorio and to be published by Springer) on the potential application of nanotubes. We examined short term (3-5 years), medium term (5-10 years) and long term(10+ years) horizons. There are currently a couple of bulk applications for nanotubes, such as in the electrodes of lithium-ion batteries. Nanotubes are also being used today in certain materials such as plastics to prevent electrostatic discharge. In the medium term, polymer composites for aerospace and sporting goods applications are probably large scale applications. In the longer term, we hope to use nanotubes in electronics.

Is it currently feasible to make nanotubes of arbitrary length? Why is nanotube length important?

It is currently not possible to make nanotubes of arbitrary length. Some envision replacing carbon fiber composites with nanotubes, but that is a long term application, since we cannot envision how to make arbitrarily long nanotubes using today’s technology. We currently make nanotubes by growing them in the vapor phase, and the tubes terminate after a certain point. But there are efforts underway to use nanotubes in composites. These composites are not as strong as traditional fiber composites, but it should be possible to create a composite embedded with short nanotubes that would be considerably lighter than carbon fiber. There are, however, several formidable technical issues involved with embedding nanotubes in a composite material, so such applications are probably at least several years from becoming commercialized.

What are the current costs per gram of pure nanotubes, and how quickly are production costs dropping?

The cost per gram of nanotubes has dropped dramatically during the past few years. Multi-walled nanotubes can now be mass-produced, so a gram would probably cost $10 or less. But single-walled nanotubes are still in the $100 per gram territory. This is partly due to the current dearth of applications for single-walled nanotubes. However, so many corporations are researching ways to mass-produce nanotubes inexpensively, and so many R&D resources are being allocated to nanotube production issues, that I am confident that the price will drop precipitously during the next five years.

You mentioned electronics as one of the primary long-term applications for nanotubes. What research is your group doing in this area?

We are concentrating our efforts on using nanotubes as interconnects. A number of my students have been hired by semiconductor companies, and we have collaborated with companies such as Intel. But this is a disruptive technology, and it will take over a decade to get these materials to replace the current copper interconnects. The tools required to make nanotubes are not compatible with traditional semiconductor equipment, and the fabs needed to make chips cannot be easily modified to accommodate nanotube placement. It is also important to remember that the semiconductor industry has been quite successful in scaling down conventional technology. There are two scenarios for using nanotubes in computers. The first would be to integrate nanotubes into conventional chips, in a hybrid scheme. This scenario is perhaps several years away. The second possibility, which is longer term, would be to use nanotubes in a completely different computing paradigm. But one can only speculate on what such an architecture would look like.

Have you formed any startup corporations? Do you plan to?

Although I have not yet formed any corporations, I am examining the prospects for creating commercial ventures. I have been consulting with several people on this, and I may decide to form a startup within the next year or so.

How many of the corporations making nanotubes will survive?

There are currently quite a few corporations selling nanotubes. Some are making them into transparent thin-films, or sensors, and quite a few are simply manufacturing nanotubes for sale. At this point it is too early to tell which will survive and become profitable. This will partly be determined by which corporations can succeed in scaling up production facilities, and also by which companies will be able to refine the process to make nanotubes more efficiently. How fast new applications emerge will be another important factor in determining which companies thrive and which fail.

What institutions/corporations are funding your research?

For the interconnect center, a portion of the research funding comes from DARPA and a portion comes from the semiconducting industry. Intel has also directly funded our research, and a number of other corporations have shown interest in our research. Although the aerospace industry is not yet providing funding, Boeing has shown an interest in nanotubes. Most of our funding comes from federal agencies such as the NSF.

Outside of your own research, what excites you, today, in small and advanced technologies?

I am particularly excited by the prospects of using nanotechnology to integrate disparate technologies. For instance, on one side is “hard” engineering, such as microelectronics technology, which has progressed at a rapid, steady pace. On the other side is “soft” biological engineering, which is more complex and has taken longer to develop. Nanotechnology facilitates the development of both fields, and makes it feasible to create useful products that incorporate both paradigms in a single platform.

How do you see carbon nanotube technology evolving in the future?

There has been tremendous advancement in manufacturing during the past several years. The factories in Japan that can produce 100 ton quantities of nanotubes for batteries is an excellent example, and I predict that these trends will continue. During the next decade there should be major strides in single-wall nanotube manufacturing, since those nanotubes could be employed in everything from fibers to transparent films. We might see the first examples of nanotubes used by the aerospace industry in structures to reduce weight. There are also opportunities in alternate energy, such as fuel cells, photovoltaics, and supercapacitors. I have been working on nanotubes since they were first created, and have personally witnessed the steady growth of the technology and the industry. If present trends continue at their current pace, the nanotube industry will be booming within a decade.

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