The Introduction of carbon nanotube dispersion

The carbon nanotube dispersion in various media and methods of using the same in such applications as inks, coatings, and composites and in various electrical and electronic articles are disclosed. A dispersant is used which has the formula P-(U-Y)s where P is a metal or metal-free phthalocyanine, Y is a compatibilizing moiety with a molecular weight between 500 and 5000 g/mol, U is a linking moiety covalently bonding Y to P, and s is an integer between 1 and 4.
Carbon Nanotubes have shown great promise as an economical alternative to making transparent conductive oxide (TCO) layers, commonly used with organic and dye-sensitized cells, as well as several other electronics applications. Sono-Tek's ability to spray carbon nanotubes makes R&D processes ideal for using ultrasonic nozzle technology. The ability to create efficient transparent conductive films with CNTs at low temperatures allows the possibility to greatly reduce manufacturing costs of the TCO layer.
(FR)L’invention concerne la dispersion efficace de nanotubes de carbone dans divers milieux et des procédés les utilisant dans des applications telles que les encres, les revêtements et les composites et dans divers articles électriques et électroniques. On utilise un dispersant de formule P-(U-Y)s, où P est une phtalocyanine contenant ou non un métal, Y est un fragment de compatibilisation possédant un poids moléculaire situé entre 500 g/mol et 5000 g/mol, U est un fragment de liaison liant par liaison covalente Y à P, et s est un nombre entier entre 1 et 4.
Parallel alignment of nanotubes can be obtained by dispersion in a self-organizing anisotropic fluid such as a nematic liquid crystal. Exploiting the cooperative reorientation of liquid crystals, the overall direction of the nanotube alignment can be controlled both statically and dynamically by the application of external fields. These can be electric, magnetic, mechanic, or even optic in nature. Employing multiwall as well as single-wall carbon nanotubes, we show their parallel alignment along a uniform liquid crystal director field and electrically verify their reorientation behavior for two complementary geometries. These demonstrate electrically controlled carbon nanotube OFF–ON and ON–OFF switches. Further applicational potential will be outlined.
Functionalization
Pristine nanotubes are unfortunately insoluble in many liquids such as water, polymer resins, and most solvents.  Thus they are difficult to evenly disperse in a liquid matrix such as epoxies and other polymers. This complicates efforts to utilize the nanotubes’ outstanding physical properties in the manufacture of composite materials, as well as in other practical applications which require preparation of uniform mixtures of CNTs with many different organic, inorganic, and polymeric materials.
To make nanotubes more easily dispersible in liquids, it is necessary to physically or chemically attach certain molecules, or functional groups, to their smooth sidewalls without significantly changing the nanotubes’ desirable properties. This process is called functionalization. The production of robust composite materials requires strong covalent chemical bonding between the filler particles and the polymer matrix, rather than the much weaker van der Waals physical bonds which occur if the CNTs are not properly functionalized.

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