The Path to the Nanotechnology Revolution
by Jian Cui and Kellen Schefter
January 3, 2003 may one day be remembered as a turning point in the "nanotechnology revolution". On this day, researchers at oil giant Chevron published in Science a novel method for extracting from oil significant quantities of a special class of nanoparticles never before observed in nature - higher diamondoids. Three years later, on the campus of Stanford University, the Stanford-Chevron Program for Diamondoid Nanoscience was founded to explore the fundamental properties of these materials.
Diamond Nanoclusters
A diamondoid is a carbon and hydrogen-based nanoparticle that is structured like a diamond crystal lattice. The structure of a diamondoid is reminiscent of both diamond Ð carbon in its most stable form Ð and known carbon nanoclusters such as carbon nanotubes and the famous 60-carbon Buckminsterfullerene, or ÒBuckyball.Ó Both diamonds and nanoclusters possess properties that are unseen in other materials. The existence of a new carbon-based nanoparticle raises an intriguing question.
Will diamondoids behave more like diamonds, other nanoclusters, or a superposition of the two?
The reason higher diamondoids have not been heavily studied in the past is simple: they are very difficult to obtain. The simplest diamondoid, adamantane, is structurally analogous to a single cage of diamondÕs lattice structure. While adamantane has been heavily studied and is commercially available today for low prices, diamondoids with more cages are difficult and costly to produce. In fact, a single isomer of a four-caged tetramantane is the most complicated diamondoid to ever be synthesized by man. Scientists have searched for these higher diamondoids that contain more than three cages in a variety of different arrangements, because they are predicted to have interesting and useful properties analogous to diamond Ð such as high thermal stability and structural rigidity Ð but on the nanoscale level.
These higher diamondoids have only recently been extracted from oil through processes that Chevron developed. As Professor Zhi-Xun Shen of Stanford's Departments of Physics and Applied Physics notes, ÒIt is much easier to extract things that already exist than to synthesize them. Basically, nature has spent millions of years with extreme temperatures and extreme conditions to generate this oil, and though it took a long, long time, natureÕs chemistry factory has done that for us.Ó The Stanford-Chevron Program for Diamondoid Nansoscience
Having unearthed sizable quantities of a previously unstudied material, Chevron made diamondoids available for scientific scrutiny by contacting various universities, including Stanford, UC-Berkeley, and MIT. According to Professor Shen, seven Stanford professors in various fields showed interest in pursuing diamondoid research. One of these professors is Dr. Nick Melosh in the Department of Materials Science. Following some preliminary experiments, Chevron determined that Stanford would be, according to Melosh, the Òmost fruitful locationÓ to establish a center for university-based diamondoid research. Hence, the Stanford-Chevron Program for Diamondoid Nansoscience emerged.
As part of the first stage in the collaboration with Stanford, Chevron is providing $1.2 million over the course of four years to support the research of three professors Ð Drs. Shen, Melosh, and Hari Manoharan in the Physics Department Ð who are investigating diamondoid properties. This collaboration could potentially expand in the future.
Funding Basic Research
Why did Chevron turn to Stanford and other universities, rather than conduct the research entirely by itself? "Investing in Stanford research is actually very cost effective," says Melosh, "because you get the best people, the best expertise, and the best equipment right away, for a relatively small amount of capital funding.Ó Tapping academic research groups harnesses the collective expertise of each individual involved and the knowledge amassed over years of experience, aided generously by outside funding such as government grants.
While on the surface this seems to be no different from most collaborations between industry and academia today, the name of the program, Program for Diamondoid Nanoscience, is the first sign of something special. Shen explains, ÒThese days, fewer and fewer industries are willing to invest in something which is very basic. We used to have places like Bell (AT&T Bell Laboratories) that were doing long-term basic research.Ó This type of collaboration is less favored today in both business and academia, where high demand for immediate results and applications dominates. In the face of this trend, "[The Stanford-Chevron collaboration] is relatively unusual," Melosh notes. "We're really exploring the fundamental properties of these new materials instead of trying to refine a process or to develop a particular material for an existing application.Ó
According to Melosh, Stanford will keep the patent rights to all of the intellectual property developed on campus, but Chevron can license these patents Òas they see fitÓ. This opens the door for Chevron Technology Ventures, a subsidiary of Chevron Corp. aimed at commercializing promising technologies, to potentially launch startup companies for marketing any processes or applications that arise from the collaboration. Such companies could contribute to ChevronÕs bottom line, but ultimately, ÒThereÕs no two year path to making a profit,Ó says Melosh. ÒItÕs a high risk, high reward kind of investment.Ó
Diamondoids and the Nanotechnology Revolution
The risk with diamondoid research is dual-layered: not only are the applications of these materials unknown, but basic research remains to prove that diamondoids exhibit the predicted unique properties. Many of these predictions, even at this point, are speculative; this is characteristic of the "nanotechnology revolution" as a whole. The possibilities are big Ð such as designing nanoparticles as tiny machines that can perform particular functions at the molecular level Ð but so are the costs. Millions of dollars and incalculable human resources are being applied to studying these new materials. Critics have found fault in the exorbitant expenditure in light of the current minimal payoff associated with the ÒrevolutionÓ so far.
Nevertheless, the researchers are patient. "Revolutions take time," says Melosh. "ItÕs not going to happen overnight." Though it may not keep pace with hype-driven expectations, the best chance nanotechnology has to deliver on its promise is to take advantage of basic research capabilities of the modern university. ÒUniversity research," explains Shen, "is the core of our nationÕs technological reserve, and even corporations in this case realize that.Ó
Fact Box
Unique Properties of Diamonds and Nanoclusters:
Diamond has a very large bandgap, high hole mobility, very high thermal conductivity, is the hardest material known, is very chemically inert, and has negative electron affinity. The advantages of nanoclusters and other nanomaterials include known processing techniques, electronic quantization, high surface to volume ratio, doping during growth, and ease of functionalization. Professors Zhi-Xun Shen, Nick Melosh, and Hari Manoharan are exploring the degree to which diamondoids share properties of diamonds and nanoclusters, because the combination of diamond's rare properties and the versatility of nanoclusters can yield unimaginably interesting and useful results. Possible applications of diamondoids include using them in a single-molecule layer in field emitter displays, using them as an alternative detector for X-rays, and using them as doped superconductors.