Carbon Nanotubes (CNT) are of great interest because of their outstanding mechanical, electrical, and optical properties. Intense research efforts have been undertaken to synthesize long aligned CNT because of their potential applications in nanomedicine, aerospace, electronics and many other areas. The long CNT arrays can be spun into fibers that are in theory stronger and lighter than any existing fibers, which will engender revolutionary advances in the development of lightweight and high-strength materials. Nevertheless, many limitations to synthesize long CNT arrays still remain. Recently, UC (University of Cincinnati) researchers developed a novel composite catalyst for oriented growth and succeeded to produce the longest CNT arrays (11.5 mm and above) reported in the literature. The length of this "black cotton" is optimal for spinning threads. The project includes intense research efforts to meet industry demand for large quantities of long nanotubes, to scale up the cultivated process, and to develop the manufacturing tools and methods that industry needs to "mass produce" nanotubes. The UC new nanotube synthesis lab and "clean room" makes these goals achievable.
The immediate objectives of this project are to develop a technique to synthesize long carbon nanotube (CNT) arrays on 10 cm diameter substrates, and to demonstrate the potential to scale-up production of nanotube arrays to larger substrates. The approach that will be taken is based on the implementation of a novel catalyst that provides tailored catalytic activity, moderate growth temperature, and an increased number of reactive growth sides. In addition, an optimized Chemical Vapor Deposition (CVD) process for growth of centimeter long CNT will be used. The large area substrate preparation will be handled by employing different thin film deposition techniques which are successfully proven in industrial environment. A series of carefully planned experiments will be performed to sequentially optimize different variables involved in nanotube synthesis, including the current catalyst composition. Scale-up of array production will involve: (i) determining the optimal parameters for catalyst deposition on 10 cm size single crystal Si substrates, (ii) employing the optimized catalyst deposition and CVD growth on larger substrates, and (iii) evaluating methods to reduce manufacturing cost per squire cm of CNT array.
The expected outcome of the project is to produce a breakthrough in nanoscale manufacturing in the US. Advances in the development of nanotube materials will have a tremendous rippling effect across all engineering and life sciences disciplines. The UC researchers have been working for four years to develop substrate processing procedures to produce dense arrays of long nanotubes. They will also work with CVD Equipment Corp. and North Carolina A&T SU to optimize substrate preparation and scale up nanotube production. One of the most important CNT array applications is to spin the nanotubes into fibers for use in advanced composite materials. The spinning will be developed by Industrial Nano, Inc. UC will produce large area, long nanotube arrays as a "black cotton" commodity for spinning into threads.
The broad impact of the proposed activities will be to kick the US economy forward by providing technology to produce commodity scale quantities of long carbon nanotubes that will enable development of ultra lightweight electrically conductive threads to replace micro fibers in composites. This will have applications in many products including aircraft such as the Boeing 787, the space elevator, aircraft engines, and sporting equipment. Another exiting field that will benefit from this research is related to successful heat dissipation from high density electronic chips and circuits, because of the excellent thermal conductivity of the CNT arrays.
The educational activity of this project involves training students in the interdisciplinary area of the emerging nanotechnology, and integrating nanostructured materials engineering and manufacturing into the curriculum to provide the future work force in the nanotechnology age.
