Carbon nanotubes are currently produced in batches and are difficult to make in large quantities. But only a handful of nanotubes made in batch possess the desired characteristics. For carbon nanotubes to be commercialized and to replace silicon wafers in electronics, they should be easy to make in the purest form possible with high precision and yield.
Berkeley Lab scientists developed a hoop-shaped chain of benzene molecules called cycloparaphenylene to improve the way carbon nanotubes are produced, and the newly synthesized nanohoop happens to be the shortest segment of a carbon nanotube and this could be used to grow much longer carbon nanotubes in a controlled way, with each nanotube identical to the next.
Thus a way to has been opened to make a single type of carbon nanotube on demand by rational synthesis. To synthesize cycloparaphenylene the scientists developed a relatively simple, low-temperature way to bend a string of benzene rings which normally resist bending into a hoop.
Carbon nanotubes are hollow wires of pure carbon which is semi conducting or metallic depending on how they’re structured to help in constructing faster and smaller computers or tiny sensors powerful enough to detect a single molecule.
The family of Cycloparaphenylene compounds forms the smallest carbon hoop structure with a set diameter and set orientation of benzene molecules, which are the two variables that determine a nanotube’s electronic properties. Because of this, cycloparaphenylene molecules could be used as seeds or templates to grow large batches of carbon nanotubes with just the right specifications.
The researchers have created a batch of carbon nanotubes that is 99 percent pure and made cycloparaphenylenes, called carbon nanohoops because they are the fundamental circular building blocks of “armchair” conformation of carbon nanotubes.
Cycloparaphenylenes are fundamental repeating units of armchair carbon nanotubes. Synthetic cycloparaphenylenes could make it possible to assemble pure armchair nanotubes under low-temperature conditions.
The diameter and structural conformation of carbon nanotubes cannot be controlled by available assembly techniques, but conceivably be controlled by using carbon nanohoops as seeds for nanotube growth.