SYNTHESIS OF CARBON NANOTUBES AND DEVELOPMENT OF REMOTE ACTUATORS

This thesis discusses the development of new multifunctional materials that are based on carbon nanotechnology. Of particular interest are carbon nanotube based smart materials that can be strong and self-sensing for structural health monitoring, or self-actuating to improve the performance and efficiency of all kinds of structures and devices. The research primarily concentrates on; (1) exploring optimum process conditions to synthesize high quality/quantity of single wall carbon nanotubes (SWCNT), (2) improving carbon nanotube purification techniques, and (3) developing new concepts of remote electrochemical actuation & remote sensing using carbon nanotubes. Towards synthesis of high quality & quantity of single wall carbon nanotube, we performed various experiments, & came up with the ‘long purge & long growth’ time recipe which gives more clean SWCNT, free from metallic catalyst particles. Also seen is an increase in the quantity of the nanotubes grown. To grow bulk quantity of SWCNT, we developed a new lithography free, powder catalyst, made out of silica/ alumina support with Fe/Mo catalyst. We also tried other potential experiments towards synthesis, like growing branched nanotubes, i.e. single wall grown on multi-wall nanotubes & tried to study the effect of gravitational field on the length of nanotubes. Long and branched nanotubes can pave way to a variety of applications dealing with nano-electronics and development of strong nano-composites. We further attempted to purify the nanotubes we grew using both thermal annealing & acid treatments in combination, using HCL, HF & HNO3 acids, and observed some improvement. To further improve the results, we tried using nickel instead of iron, to develop the powder catalyst, supported on silica, assuming that nickel would be more efficiently washed with the above acids. We achieved better results using the new nickel based recipe. Finally we thought of novel concepts of remote electrochemical actuation and sensing applications using nanotubes. We used both commercial SWCNT & also the nanotubes we grew and purified at University of Cincinnati. We tried to completely model the electrochemical remote actuation phenomenon, studying impedancefrequency & phase shiftfrequency characteristic of the electrode-electrolyte and nanotube-electrolyte interfaces. The experiments, to our knowledge are done first time in the history of smart materials, and provide the smart materials with a completely new set of capabilities. Such capabilities would engender a wide range of applications in the field of biomedicine. Applications envisioned include treating malignant growths and tumors, treating arteriosclerosis, reducing the risk of heart failures by continuously eliminating the cholesterol growth in the arteries, and delivering nanotubes as a structural reinforcement to mix with biological materials used in the repair of muscle tears and bone fracture. Finally a list of innovative ideas based on carbon nanotube /fibers smart materials is notified. The ideas include (a) smart drug delivery fish, (b) detecting cancer using impedance-frequency experiment, (c) lowering the fluid impedance manifolds by dispersing SWCNT in it & (d) power harvesting using SWCNT. The ideas are still in a very nascent stage, but if tried successfully have the potential to revolutionize a variety of future applications in the field of science & technology.