Dramatic Effect of Dispersed Carbon Nanotubes on the Mechanical and Electroconductive Properties of Polymers Derived from Ionic Liquids

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2006-04, Vol.2 (4), p.554-560
• Main Authors: Fukushima, Takanori, Kosaka, Atsuko, Yamamoto, Yohei, Aimiya, Takuji, Notazawa, Shunsuke, Takigawa, Toshikazu, Inabe, Tamotsu, Aida, Takuzo
• Format: Article
• Language: English
• Subjects: carbon nanotubes; Colloids - chemistry; composites; conducting materials; Crystallization - methods; Elasticity; Electric Conductivity; Electrochemistry - methods; ionic liquids; Ionic Liquids - chemistry; Macromolecular Substances - chemistry; Materials Testing; mechanical properties; Mechanics; Molecular Conformation; Nanotechnology - methods; Nanotubes, Carbon - chemistry; Nanotubes, Carbon - ultrastructure; Particle Size; Polymers - chemistry; Solutions; Stress, Mechanical; Surface Properties
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.200500404

Free‐radical polymerization of an imidazolium ion‐based ionic liquid bearing a methacrylate group, gelling with single‐walled carbon nanotubes (SWNTs), allows fabrication of a mechanically reinforced, electroconductive soft material (bucky plastic). A film sample of this material displays an excellent conductivity of 1 S cm−1 and a 120‐fold enhancement of the Young’s modulus at a 7 wt % content of SWNTs. The conductivity is temperature‐dependent in the range 5–300 K, suggesting that the conductive process involves carrier hopping. Scanning electron and atomic force micrographs of a bucky plastic film display the presence of crosslinked networks consisting of finely dispersed SWNTs. Such nanotube networks, developed in the polymer matrix, likely suppress slipping of entrapped polymer molecules via a strong interfacial interaction and also facilitate intertubular carrier transport. Although a bucky plastic derived from a vinylimidazolium ion‐based ionic liquid monomer shows a comparable conductivity to that of the methacrylate version, the film is brittle irrespective of the presence or absence of SWNTs. Soft materials with carbon nanotubes: Grinding a polymerizable ionic liquid containing finely dispersed single‐walled carbon nanotubes (SWNTs) forms a gel, which is converted into a highly electroconductive soft material (see figure). Crosslinked SWNT networks suppress slipping of entrapped polymer molecules via a strong interfacial interaction and also facilitate intertubular carrier transport.