Milo Shaffer speaks to Glass about Nanoscience and the future of planes, trains and bulletproof clothing
Buckminster Bio Dome - The former Expo 67 United States of America Pavilion designed by Buckminster Fuller, seen here in the fall of 2004.
This illustration depicts eight of the different molecular configurations that pure carbon can take. Image by Michael Ströck
'BuckyBall'. Molecular structure of the buckyball. Courtesy of Professor Francesco Bennardo
Scanning electron microscope image of carbon nanotube bundles
Milo Shaffer completed his PhD at Cambridge in 1998. Following a period working as a materials technology consultant focusing on technology exploitation and innovation, he enjoyed a research fellowship at Trinity College, Cambridge. He joined Imperial College London in 2003, and is now a professor of Materials Chemistry.
From the ancient Egyptians to the mid 20th century civilization's great achievements were big: pyramids, stadia, cathedrals. Only comparatively recently has engineering got to grips with the small: quantum physics computer chips.
The natural world remains way ahead of us at incorporating complex design at every size scale. Atom to molecule to membrane to cell and up, up, up. The complexity is mind-boggling. To even start approaching multi-level design, science needs to provide new bricks at intermediate scales; this is where nanoscience steps in.
Dr. Milo Shaffer is working to bridge this gap in our ability to manipulate the world around us. His work focuses on the carbon nanotube. Nanotubes are pipes with walls as thin as atoms and diameters as small as a millionth of a millimeter that have recently been used to create transparent speakers of nanometer thickness and the world’s toughest fibers. They act as a versatile building block, realizing sci-fi technologies and making good, existing materials, vastly stronger.
Think of the different versions of carbon that exist. Graphite; opaque, soft and flaky. Perfect for pencil lead. Or diamond: transparent and dense. The difference is in the arrangement of the atoms. In the form of a nanotube, carbon has interesting optical and electrical properties unavailable in its other forms. It is also very strong. Hence new technologies are possible.
Milo explains the beginnings of the nanotube, starting with carbon.
"Everyone knew about graphite, diamond and soot and they thought that was it. Until about 1985, when interest in fullerenes began, fullerene being a family of carbon molecules [shaped like balls, ellipsoids or tubes]. Fullerenes were a surprise. The most famous is C60 Sixty carbon atoms arranged to look much like a conventional football."
C60 was the happy bi-product when gas clouds seen in deep space were recreated in the lab. Robert Curl, Harold Kroto and Richard Smalley saw an unexpected amount of a heavy unknown molecule when analyzing the data from their synthetic cloud. Leading to a Nobel Prize in 1996, this was the first evidence of “buckyballs”, named in homage to Buckminster Fuller, as their structure resembled his famous domes.
This regular structure had a certain aesthetic appeal and the new molecule was thrown into every problem in the hope it might create a revolutionary technology or material, based on the unstated assumption that, since C60 was beautiful, it must surely be useful.
Unfortunately nature has disagreed. C60 has found relatively few applications despite continued attempts to apply them to solar cells or new drug delivery methods. However, interest in the fabrication of nanostructures was piqued and soon new nano structures were emerging.
Milo continues: " Around 1991 Iijima was the first to describe the structure of nanotubes. You can think of these in two ways. Think of the C60 ‘footballs’. Add a belt of hexagons around the middle of [the ball] you would make it a bit longer. If you keep adding more and more hexagons in this way you eventually get a tube. The body of this would be a nanotube, but it would be capped at both ends.
Alternatively you can roll up a flat sheet. Imagine that one layer of graphite looks like chicken wire, and you could roll it up into a tube. You can have different families of tubes depending on how you roll (the diameter and alignment of the hexagons will change). This changes the properties of the tube."
Combination of the nanoscale with the existing materials opens new possibilities. "Nature is very good at organizing everything on every length scale, but we are hopeless!" Milo is especially interested in the incorporation of these tubes into existing larger systems. For example:
"Conventional fiber composites are current "state of the art" structural materials, but they have lots of problems. If you load them in compression, the fibers tend to buckle sideways, or their fiber layers can split apart from each other. You could address this problem by introducing nano reinforcement "
Imagine the fibers of these fiber composite made hairy with nanotubes, then when the material is put together this perpendicular reinforcement will inhibit the buckling of the material. This improvement through the introduction of a smaller scale object to the structure of the material is a first step towards the fluidity in design seen in nature.
Carbon nanotubes can also be used in isolation. Super strong fibers made exclusively from carbon nanotubes are being currently researched. They have been shown to be lighter, tougher and more durable than carbon fiber currently used in cars, boats and aircraft. These fibers, strong enough to stop bullets, have many applications outside the traditional uses of carbon fiber like lightweight body armor or durable tethers for off shore wind turbines.
"People are getting better at building more complicated objects from the bottom up; building bigger molecules, building super assemblies of molecules, directing the assembly of complex structures by controlling the chemistry... this is all quite exciting!"