Carbon nanotubes: high solids dispersions and nematic gels thereof

Abstract

Disclosed are high weight fraction carbon nanotube dispersions including an aqueous medium, carbon nanotubes, and at least one surfactant, the surfactant having an aromatic group, an alkyl group having from about 4 to about 30 carbon atoms, and a charged head group. Also disclosed are ultrasonication processes capable of providing stable dispersions of carbon nanotubes having reduced breakage of the carbon nanotubes. The preparation of nematic nanotube gels from the carbon nanotube dispersions are also disclosed. A variety of uses and applications of the carbon nanotube dispersions and nematic nanotube gels are provided.

Description

GOVERNMENT RIGHTS [0001] The work leading to the disclosed invention was funded in whole or in part with Federal funds from the National Science Foundation. The Government may have certain rights in the invention under NSF contract DMR0079909.FIELD OF THE INVENTION [0002] The present invention is related to the field of carbon nanotubes. The present invention is also related to dispersions containing carbon nanotubes. In addition, the present invention is related to the field of materials and devices that contain carbon nanotubes. BACKGROUND OF THE INVENTION [0003] Carbon nanotubes are tiny fullerene-related structures of graphene cylinders having nanoscale diameters from about 0.7 to about 50 nanometers (“nm”) and microscopic lengths from about 0.1 to about 20 microns (“μm”). Carbon nanotubes are readily synthesized catalytically from hot carbon vapor or by thermal decomposition of a carbon-containing gas or liquid. Different synthetic methods yield nanotubes with one or several ne...

AI Technical Summary

Benefits of technology

[0019] The present inventors have discovered that a particular class of surfactants is capable of providing stable dispersions of high concentrations of carbon nanotubes in aqueous media without requiring the aforesaid techniques of chemical modification or polymer wrapping. I

Problems solved by technology

Unfortunately, as a result of the substantial van der Walls attractive forces between them, nanotubes readily aggregate and are difficult to keep individually dispersed in solution.

Generally, the chemically modified carbon nanotubes are less desirable because their band structures can differ from the unmodified nanotubes.

Unfortunately, tube breakage typically accompanies preparation of dispersions of carbon nanotubes longer than about 500 nm.

Thus, there remains the problem of providing carbon nanotube dispersions that do not require chemical modification and which provide high volume fractions of long carbon nanotubes with minimal breakage.

Aligning carbon nanotubes has been difficult, however.

Thus, there also remains the problem of providing oriented ensembles of carbon nanotubes.

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