University:
Boston University
Course:
CAS PY 105 | Physics 1
Academic year:

2024
Views:

82

Pages:

15
Author:

Aryan Henderson

Stronger than Steel: Carbon Nanotubes How small is nano ? nano? Nano-hype! Nano -hype! Today ’s Nanotube Workshop Today’s • The Chemistry of Carbon A New Form of Carbon: Nanotubes Activity: Building Nanotube Models • Nanotubes in Biology and Medicine Biosensors Filtration of Biocontaminants • Carbon Nanotubes – Stronger than steel Tensile strength of Carbon Nanotubes Composite Materials Applications Chemistry of Carbon Forms of Carbon • Carbon was discovered in prehistory and was known to the ancients •The allotropes of carbon are the different molecular configurations that pure carbon can take. •The three relatively well-known allotropes of carbon are amorphous carbon, graphite and diamond. • Several exotic allotropes have also been synthesized or discovered, including fullerenes and carbon nanotubes. Graphite • Graphite is a conductor, and can be used as the material in the electrodes of an electrical arc lamp, or as the lead in pencils. • Each carbon atom is covalently bonded to three other surrounding carbon atoms. •Each carbon atom possesses an sp2 orbital hybridization. The pi orbital electrons delocalized across the hexagonal atomic sheets of carbon contribute the graphite's conductivity. Diamonds • Diamonds typically crystallize in the cubic crystal system and consist of tetrahedrally bonded carbon atoms • The tetrahedral arrangement of atoms in a diamond crystal is the source of many of diamond's properties; graphite, has a rhombohedral crystal structure and as a result shows dramatically different physical characteristics—contrary to diamond, graphite is a very soft, dark grey, opaque mineral. History of Carbon Nanotubes • In 1985 a new class of molecules consisting of purely carbon was discovered, the Fullerenes. • In 1990 Dr. Richard Smalley recognized that tubular Fullerenes should be possible. • It was not until 1991 that Sumio Ijima of the NEC Laboratory in Tsukuba, Japan, observed that these fibers were hollow. Fullerenes • • The Fullerenes are a recently discovered allotrope of carbon. Fullerenes are not very reactive due to the stability of the graphite-like bonds Carbon Nanotubes • • Carbon nanotubes are cylindrical carbon molecules with novel properties that make them potentially useful in a wide variety of applications. Nanotubes are composed entirely of sp2 bonds, similar to graphite. What makes nanotubes different from one another? Inquiry Activity Buckyballs Nanotubes Ideal sensor molecule • Remarkable Properties of CNTs Carbon Nanotubes “glow” Excited in the near-IR range of the EM spectrum Different than almost all other dyes Continuous fluorescence- no photobleaching • Ideal for sensor applications in the body Nanotubes and medicine • Fluorescence of nanotubes can be used to make biosensors • Light and the human body Different wavelengths interact with tissue differently Familiar with X-rays Window into tissue “There is a window in which light can penetrate into tissue: the near-IR wavelengths, from approximately 700 to 900 nm.” Red is good Near-IR is best