Anisotropic and Isostropic CNT Sheets
Karlheinz Strobl1, Mathieu R. Monville1, Subarna Banerjee1, Shihsheng Chang1
1CVD Equipment Corporation, 355 S. Technology Drive, Central Islip, New York 11722, USA
Our standard large area (> m2) CNTSheet™ manufacturing process produces anisotropic porous carbon nanotube sheets in the 10-200μm thickness range. They have electrical and thermal properties that are uniform in the “X” and “Y” direction (sheet plane) and are 1-3 orders of magnitude lower in the “Z” direction. This manufacturing platform, using mm long VASWCNT’s or VAMWCNT’s as the primary mechanically interlocking fiber material, allows us to create a large family of macroscopic 2D materials, whose porosity can be easily tuned. These can be used as nanofilters, ultra-light and thin EMI attenuation sheets, batteries/ultracapacitors/capacitative desalination electrodes, water purification filters, catalysts, etc. Due to the versatility of the manufacturing process, additional functional materials can easily be incorporated in the body or preferentially on the surface of the sheets, such as graphene, nano/micron size particle/filamentary/fiber material(s), etc. in a mechanically interlocked and electrically interconnected fashion. These 2D NanoToMacro™ sheets thereby allow us to greatly simplify the design, cost and manufacturing complexity of many next generation products enabled by nanomaterials.
In this paper, we demonstrate for the first time control of the directional properties of the sheets: from anisotropic to nearly isotropic in 3D. This directional tunability has a substantial effect on the 3D mechanical, electrical and thermal performances of the resulting materials. The availability of these additional process control options over our standard CNTSheet™ manufacturing platform is expected to further increase the value proposition and accelerate the commercialization of a range of new nanomaterial enabled products.
Presented at MRS Spring 2013 in San Francisco, CA