Dispersion and Orientation Control of Carbon Nanotubes
Nanotube/ionic liquid crystal composite for soft electronics
Graduate School of Engineering / Faculty of Engineering
University of Tokyo Graduate School of Engineering Professor Takuzo Aida and graduate student Jeongho Jay Lee and research collaborators at RIKEN, Tsukuba University and the Tokyo Institute of Technology, have developed a liquid crystal material that contains carbon nanotubes 1,000 times more dispersed than other such materials created to date. It is possible to control the orientation and electrical conductivity of the material.
Carbon nanotubes have excellent mechanical and electrical properties and are expected to lead to many new materials and industrial applications, but to take advantage of their characteristics they need to be highly and individually dispersed. However, while conventional methods of mixing carbon nanotubes with liquid crystal enabled control of orientation, affinity for the liquid crystal was poor and it was not possible to disperse an amount sufficient for practical applications. Previous studies had discovered that the surfaces of carbon nanotubes are abundant in negative pi-electrons, from which it was apparent that carbon nanotubes should have good affinity for positively charged ionic liquids.
The research group mixed carbon nanotubes with an ionic liquid crystal known to have excellent orientation and with more ionized imidazolium groups than other liquid crystals, and achieved an increase in distribution of five to ten percent by weight reulting in a highly efficient dispersion more than 1,000 times existing liquid crystals. Further, when examining the combined material closely, mixing with carbon nanotubes resulted in a vertically-aligned liquid crystal, and that it was possible to control independently the orientation of the liquid crystal and carbon nanotubes by application of heat and shear force. This result is an important step forward in the development of materials for soft electronics.
The results of this research have been published as a Very Important Paper in the online version of the journal Angewandte Chemie International Edition, and in addition has been selected for the back cover.
Press release (Japanese)
Jeongho Jay Lee, Akihisa Yamaguchi, Md. Akhtarul Alam, Yohei Yamamoto, Takanori Fukushima, Kenichi Kato, Masaki Takata, Norifumi Fujita, Takuzo Aida,
“Discotic Ionic Liquid Crystals of Triphenylene as Dispersants for Orienting Single-Walled Carbon Nanotubes”,
em>Angewandte Chemie International Edition Online Edition: 2012/07/24 (Japan time), doi: 10.1002/anie.201205477.