Carbon nanotubes are remarkable nanostructured fibers with diameters only a few times larger than atoms themselves. Nanotubes are known for having the highest strength-to-weight ratio of any known material, excellent electrical and thermal conductivities, and many other amazing properties. Thanks to their ultrasmall diameters and incredible strength properties, nanotubes can be used to make composites such as fiberglass and carbon fiber stronger and tougher by reinforcing the microscopic interstitial expanses of epoxy in these materials where cracks can form and propagate. Nanotubes can be introduced into composites by growing them directly on fibers used to make composites. Growing nanotubes on things like carbon fibers is challenging, however, since the nanotube growth process typically occurs at temperatures of 700 degrees Celsius (1300 degrees Fahrenheit) and requires the use of nanoscopic metal seeds that can eat away at the material they sit upon.
In the course of my PhD, we discovered that nanoscopic seeds of zirconia, an oxide (think fake diamonds), can also grow nanotubes. Such zirconia seeds open possibilities for growing nanotubes on substrates that have been historically challenging to grow on. Frustratingly, however, the legacy methods used for growing nanotubes with metal seeds do not work well with zirconia, and the reasons why this is the case remained elusive even after performing a parametric study surveying 200 different experimental conditions.
In this performance, a method effective at growing nanotubes with zirconia is depicted through interpretive dance. First, zirconia attempts to interact with the typical carbon-containing gases used to grow nanotubes with metal seeds (such as alkenes and alkynes) but is rejected. An idea then emerges: perhaps pretreatment of zirconia with solid-state amorphous carbon will help. Upon heat treatment in the presence of solid carbon, zirconia organizes the disordered carbon around itself into a crystalline shell called a fullerene. Once surrounded by this fullerenic shell, introduction of carbon-containing gases can finally result in nanotube growth. This performance is dually emblematic of the frustration encountered by the PhD candidate in the course of trying to understand why processes used for nanotube growth with metal catalysts do not work well with zirconia.
This work was prepared for submission to the 2011 "Dance Your PhD Contest".
PhD Candidate: Dr. Stephen A. Steiner III, Department of Aeronautics and Astronautics, MIT
Produced and Directed By: Will Walker and Stephen A. Steiner III
Zirconia - Stephen A. Steiner III
Alkyne - Candice Beermann
Alkene - Eleanor Millman
Amorphous Carbon 1 - Laura Jeanty
Amorphous Carbon 2 - Buro Mookerji
Amorphous Carbon 3 - Evan Moran
Amorphous Carbon 4 - Sean Yamana
The Original Scientific Article: dx.doi.org/10.1021/ja902913r
MIT News Article: web.mit.edu/newsoffice/2009/nanotubes-0810.html
MIT NECST Group Home Page: necst.mit.edu