The 2004/2005 George D. Graffin Lectureship in Carbon Science and Engineering

Dr. Robert H. Hurt
Professor, Division of Engineering
Brown University

Nature's Minuet in C: Thermal, Catalytic, and Supramolecular Routes to New Carbon Nanomaterials

The American Carbon Society supported by grants from the Asbury Graphite Mills, Inc., sponsors this lecture series in North American Universities in honor of George D. Graffin, a pioneer in the natural graphite industry. Each year the Society selects a lecturer who has made distinguished contributions to carbon science and engineering. The lecture is available to North American universities, by arrangement with the lecturer.

Abstract: Elemental carbon assembles into diverse nanoforms that include fullerenes, onions, shells, "horns," films, and "peapods" as well as numerous nanotube and nanofiber varieties. There has been an explosion of interest in these materials and their applications as key components in the national nanotechnology initiative. These new nanomaterials are best understood as members of the larger carbon material family, that includes fibers, composites, sorbents, and structural graphite.

This talk presents basic principles of carbon science relevant to all sp2-hybridized carbon forms, whether nanometric or macroscopic. The talk will then survey a wide range of new carbon nanomaterials discussing synthesis, structure, and properties, and presenting selected applications and their development status.

Three classes of synthesis approaches can be identified: atomic assembly at high-temperature, catalytic assembly at moderate temperature, and supramolecular assembly at low temperature. Catalysis is a particularly flexible tool for molecular engineering of carbon, which is achieved by precipitation of aligned graphitic material from specific crystal facets of dynamic inorganic nanoparticles. Special emphasis will be given to the new supramolecular approach, in which polyaromatic disk-like compounds containing the graphitic kernel are first assembled by physical forces at low temperature and then "covalently captured" by heating to produce carbon nanomaterials whose crystal structures reflect the original supramolecule.

The talk will end with a brief discussion of the potential impacts of carbon nanomaterials on human health, which may present barriers to their commercial success. Research in this rapidly developing area seeks to quantify health impacts of specific commercial materials, but also to understand toxicity mechanisms and the detailed roles of particle size, shape, and impurity levels. These mechanistic studies have the potential to guide industrial manufacturing and purification processes toward conditions that minimize intrinsic toxicity.