“We could build that, if only we could develop unobtanium.” It’s a running joke in the engineering community, because a lot of the really exciting, futuristic designs and ideas fail to take into account materials. My favorite pet example is the space elevator, a concept for an orbital transport that runs a car along an electromagnetic cable suspended between a ground station near the equator and a space station in geostationary orbit. Of course, one of the most significant hurdles to the design is the fact that no currently available material has the necessary strength-to-weight ratio to be used for the cable. Steel, aluminum, titanium: they would all collapse under their own weight, even if you did manage to create a cable with a length of some forty thousand kilometers, so the mystery material that would enable such a cable is called “unobtanium” – the unobtainable material.
It was in the context of research on the space elevator, actually, that I first came across carbon nanotubes, probably in the fifth or sixth grade. Here, it seemed, was something that might actually have the properties of the mythical unobtanium: harder than diamond, tougher than rubber, and with a better strength-to-weight ratio than titanium. A year or two later, I had the opportunity to do a quick presentation on carbon nanotubes at a local university doing a conference on nanotechnology, which gave me the impetus to learn about bucky balls and bucky tubes and all kinds of other variations on carbon nanotube technology. I came to see them as a miracle material to solve so many of our problems, but there was a catch: they were very difficult to produce, especially at scale.
Years passed, and while I still get excited about carbon nanotubes, I have come also to know about their material drawbacks and limitations. Most of their applications are decidedly more mundane than a forty thousand kilometer cable for a space elevator, but they still have the potential to enable a lot of new technologies and capabilities that are currently either beyond our reach, very inefficient, or very expensive. When I saw a headline in this week’s issue of Science Advances, though, my old excitement returned.
The research paper is “Versatile acid solvents for pristine carbon nanotube assembly,” and it describes a new acid solvent system that does not feature the extremely challenging types of acids traditionally used in carbon nanotube production, which apparently have a tendency to form new acids when exposed to water, even the water in air, instead of being diluted. If you don’t want to dig through the paper itself, there is also a focus piece, “Safer carbon nanotube processing expands industrial and consumer applications,” which does a decent job of summarizing the paper’s findings and elucidating how they may prove relevant.
Our ideas often outpace our practical abilities to implement them, and one of the constraining factors has long been materials. That’s just one of the reasons I’ve often told people who don’t know what they want to do with their lives that they should study materials science, so that they can invent me materials to use in building interstellar spacecraft. It’s also why I found The Substance of Civilization and its lens of materials as a means to examine human history so fascinating. The innovations detailed in this Saturday’s articles might not lead us to building a space elevator tomorrow, but they are still an exciting step forward in the substance of our coming civilization.