Researchers at the University of Michigan have developed a “perfect black” carbon-nanotube coating that conceals an object’s three-dimensional geometry and makes it look like a flat black sheet. The 70-micron coating, or carbon-nanotube carpet, is about half the thickness of a sheet of paper and absorbs 99.9 percent of the light that hits it. According to Jay Guo, a professor in the Department of Electrical Engineering and Computer Science, and principal investigator, “It’s not cloaking, as the object can still cast a shadow. But if you put an object on a black background, then with this coating, it could really become invisible.”
The refractive index of this new coating is similar to that of air, meaning light traveling through air doesn’t scatter or reflect when it hits the coating, causing the human eye not to perceive it. The coating could have a variety of applications, including display screens with ultrahigh contrast and a crisper picture, solar heating devices, and a new type of camouflaging paint for stealth aircraft.
Farther south, researchers at North Carolina State University are examining the use of conductive nanocoatings on simple textiles, like woven cotton or even a sheet of paper. According to Dr. Jesse Jur, Assistant Professor of Textile Engineering, Chemistry and Science, finding a way to apply conductive nanocoatings to textiles would represent a cost-effective approach and framework for improving current and future types of electronic devices. The potential for this research lies heavily in health and monitoring applications, including a uniform with cloth sensors embedded in the actual material that could track heart rate, body temperature and movement in real time.
Nanotechnology is one of our topics in this issue of PCI. Be sure to read the article by BYK-Chemie on page 16, which reports on recent advances in using additives based on carbon nanotubes to enhance the electrical conductivity of several coating systems. Carbon nanotubes can offer an interesting alternative to the typical conductive pigments like carbon black or metallic particles.
This truly is an exciting time to be in the coatings industry. At the rate that nano research is moving, perhaps turning a piece of paper into a computer tablet or creating Harry Potter’s invisibility cloak aren’t that far away from becoming reality!