(34c) A New Approach to Nanotube Based Bulky and Thin Film Material: the Composites from Polyaniline and Derivatives

Nanotube based composite material has gained wide attention recently due to its unique thermal, electrical, and mechanical properties. Most of these preparation involve chemical synthesis, chemical vapor deposition, plasma fabrication, and most often, result in insulating composites. Conductive nanotube composites, on the other hand, usually use approaches such as layer-by-layer assembling, guest-host chemistry, and template imprinting techniques. These techniques often generate non-homogeneous composites that are subject to unexpected features and unpredictable properties.

In this work we present a new approach to make nanotube based bulky and thin film composites. Our method employs a high energy curing treatment of the nanotube-aniline dispersion, followed by a solution electrochemical conditioning. The curing process can be any energy-elevated treatment like UV radiation, heating, or others, whereas the subsequent electrochemical conditioning can be carried out in aqueous media with wide pH range from extremely acidic to weak basic conditions. The model monomers for our proof-of-concept experiments were aniline and multiwalled carbon nanotubes ( MWCNT ).

The resultant composite can be formed in either bulky or surface membrane state, depending on the reaction media and support matrix. In our study, we focused on the surface membrane protocol because of its ease for subsequent surface characterization. This formed polyaniline ( PAn ) ? MWCNT composite film is stable, redox-active, and thickness-controllable. Moreover, our new approach for fabrication produces the more homogeneous composite than the composite generated with procedures described previously. For the aspect of potential application, the new PAn-MWCNT exhibited electrocatalysis, high capacitance, and strong adsorption properties. Although our discussions have been focusing on the PAn-MWCNT surface membrane, our finding also revealed single walled carbon nanotubes ( SWCNT ) and other aniline derivatives have similar features as PAn-SWCNTs. A more systematic study is underway.

This work was supported by the ORC grant from UH-Downtown, the Starter Award from Society of Analytical Chemists, the US ARO grant ( No. W911NF-04-1-0024 ), and Welch Foundation ( No. BJ-0027 ).