RESS (Rapid Expansion Supercritical Solution) Technology to Disperse Carbon Nanotubes into Selected Polymeric Matrices

As a conductive material for EMI shielding, carbon nanotubes hold significant promise. Carbon nanotubes are conductive, nanometerthin fibers that can be many microns in length. They are a mechanically robust material—100 times stronger than high-strength steel and six times lighter. Carbon nanotubes can stretch beyond 20% of their resting length without damaging their structure or conductivity. Carbon nanotubes have extremely high aspect ratios (length/diameter), and thus form conductive percolation networks through materials more easily than other conductive fillers such as carbon fiber or carbon black. Because they form conductive composites at such low loading ratios, carbon nanotubes could be a key component in EMI shielding. However, current manufacturing process for carbon nanotube EMI shielding is expensive, scales poorly, and makes use of volatile organic compounds (VOCs). These limitations are a related to the process for dispersing the carbon nanotubes in the polymers. A rapid expansion of supercritical solutions (RESS) process for dispersing carbon nanotubes in polymers has the potential to overcome these limitations. Under this Phase II SBIR effort, Minnesota Defense, Arizona State University, and Lockheed Martin propose to develop a robust method of dispersing carbon nanotubes in polymer composite shielding/coating material processed via rapid expansion from supercritical fluid solution (RESS).