NIRT: Nanotube Based Structures for High Resolution Control of Thermal Transport

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AbstractProposal Number: CTS-0404370Principal Investigator: Cecilia D. RichardsAffiliation: Washington State UniversityProposal Title: NIRT: Nanotube based structures for high resolution control of thermal transportThis proposal was received in response to Nanoscale Science and Engineering initiative, NSF 03-043, category NIRT. The focus of this work is the use of mixed-scale architectures to bridge scales from nanometer level structures to micrometer level components to millimeter level devices and materials. We propose to incorporate carbon nanotubes into microscale composites to create a new kind of mesoscale device, a thermal switch. Arrays of thermal switches will then be produced in batch to create sheets with spatially and temporally controllable "digital" thermal conductivity. Mixed-scale architectures can be used to bridge scales from nanometers to micrometers to milimeters in order to manufacture materials and devices whose pertinent dimensions range from nanoscale to microscale to mesoscale. Carbon nanotubes (CNT's) are inherently one-dimensional mixed-scale structures, with diameters in the range of nm and lengths in the range of mm. We take advantage of this 103 aspect ratio to bring superior thermal and mechanical properties (due to the CNT's nanometer scale diameters), to micro-scale components (making use of the CNT's micrometer scale lengths). Many microelectromechanical systems (MEMS) are also inherently two-dimensional mixed-scale structures with thicknesses in the range of mm and planar dimensions in the range of mm. We take advantage of this 103 aspect ratio, to bring the superior thermal and mechanical properties of the micro-scale components to effective use on the meso-scale. Carbon nanotubes will be synthesized and then extensively characterized. The nanoscale thermal and mechanical properties of the CNT's will be modeled. The CNT's will then be assembled into aligned arrays within a matrix and formed into micron scale blocks. The thermal and mechanical properties of the aligned CNT composite blocks will then be characterized and modeled. Finally, the CNT composite blocks will be utilized to fabricate prototypes of thermal switch devices.The educational plan targets undergraduates, under represented groups, K-12, and teachers. This work will result in strong interactions between a large, rural research institution and two urban campuses, making it easier for students from a wide range of demographics to participate in cutting edge research projects. Instrumentation for characterizing thermo-mechanical responses of nanotube assemblies will be created, allowing future work to proceed in these areas. High school teachers from the Northwest will be able to get hands on tools to bring nanotechnology back to their schools, helping to motivate future generations of scientists and engineers. Research on this project will closely couple undergraduates and graduate students, helping to foster integrating research into all levels of education, particularly in groups traditionally under-represented from science and engineering. The research is being funded by the Thermal Transport and Thermal Processing Program of the Chemical and Transport Systems Division.