1. We have created carbon nanotube (CNT) aerogels that can support thousands of times their own weight. An aerogel is an ultra-low density, highly-porous material derived from a gel in which the liquid component has been replaced by gas. Fabrication of aerogels based on carbon nanotubes offers potential for applications such as ultra-light structural materials, radiation detectors, thermal insulators, sensors and electrodes. In Advanced Materials 19, 661 (2007) we report on CNT aerogels produced by freeze- and critical-point-drying liquid suspensions filled with carbon nanotubes. Pure aerogels produced in this way are fragile, but when reinforced with polyvinyl alcohol (PVA), the material is rendered stronger and more stable. The aerogels exhibit large, electrical conductivities, that can be manipulated in- situ, and the possibility of backfilling the aerogels with polymers and other materials provides a new basis for creation of novel composite materials based on CNTs. Images of Aerogels. a) Macroscopic pieces of CNT aerogels. Pristine carbon nanotube aerogel (left) appears black, while the aerogel reinforced in a 1 wt% PVA bath (right) is slightly gray. b) Three PVA-reinforced aerogel pillars supporting ~8000 times their weight. c) Scanning electron microscope image of an aerogel reveals an open, porous structure. d) Transmission electron microscope of the same aerogel reveals small-diameter CNTs arranged in a classic filamentous network. A Heavyweight Lightweight Material: Carbon Nanotube Aerogels Arjun G. Yodh, University of Pennsylvania, DMR 0505048 and DMR 0520020

2. Education: Five other scientists have contributed significantly to the interdisciplinary paper reported in this nugget. Mateusz Bryning, Mohammad Islam and Larry Hough contributed from my lab, and Daniel Milkie from Jay Kikkawa’s lab (also at PENN). Mateusz finished his PhD thesis very recently and is currently looking for a job in industry; Mohammad was a post-doc in my group who has recently begun a faculty position at Carnegie Mellon (Depts. of Chemical Engineering and Materials Science); Larry was a post-doc in my group who has recently taken a technical staff position at Rhodia Inc. Daniel is finishing his PhD in Kikkawa’s group. From a broader perspective, the soft materials research in my lab, including the carbon nanotube work, has provided hands-on opportunities for others including undergraduate students (Ran Tu, Jonathan Kanatous), PhD students (Andinita Basu, Dan Chen), post-docs (Ahmed Alsayed, Yilong Han, Zhexin Zhang), faculty at nearby four-year colleges (Kevin Aptowicz, Piotr Habdas, Peter Collings) and even a High School Teacher (Seth Baron). A Heavyweight Lightweight Material: Carbon Nanotube Aerogels Arjun G. Yodh, University of Pennsylvania, DMR 0505048 and DMR 0520020 Societal Impact: My research focuses on fundamental and applied questions in soft condensed matter. If successful, new information based on this research will impact our ability to manipulate particles (e.g. micro- and nano-particles, carbon nanotubes) and macromolecules in solution. This new control, in turn, interfaces with a variety of industrial problems ranging from the formulation of paints, cosmetics and food-stuff to photonics. Thus this research holds potential to positively impact the US technology infrastructure and economy. For example, the Intellectual property generated from our research on single-wall carbon nanotubes has already led to the formation of a start-up company based in Philadelphia (NanoSelect Inc.), and our research has recently attracted a broad collaboration with a nearby company, Rhodia, Inc.