Carbon nanotube gel, a liquid crystalline material consisting of single-walled
nanotubes, has been made by physicists at the University of Pennsylvania.
Basically the gel is a mass of half-micron long nanotubes, aligned like
little logs along a single direction, in a polymer matrix. The gel exhibits
hallmark properties of a nematic liquid crystal (in which rod shaped
molecules are aligned) including optical anisotropy (birefringence)
and topological defects.
The gel's anisotropic characteristics and its sensitivity to changes
in solvent quality might make it a candidate for novel applications.
It could be useful, for example, as an osmotic or an electrical actuator
in which changes in electrical field or salt concentration produce volume
and shape changes.
The gel was made by coating the nanotubes with surfactant chemicals and mixing in polymers which form a cross-linking network among the tubes. Next the volume was compressed. The resultant densities of isolated single-wall nanotubes are higher than can be produced in simple aqueous suspensions. (Islam et al., Physical Review Letters, upcoming article; contact Arjun G. Yodh, email@example.com, 215-898-6354, Mohammad Islam, firstname.lastname@example.org, or Tom Lubensky, email@example.com.)