The latest use for graphene – non-toxic hair dye
Graphene, the "wonder material" composed of one-atom-thick sheets of linked carbon atoms, now has yet another potential application. Led by Prof. Jiaxing Huang at Illinois' Northwestern University, scientists have used it to create a hair dye that's far less harmful than regular dyes.
Ordinarily, hair dyes incorporate harsh chemicals such as ammonia and bleach. These are used to pry open the overlapping scales that make up each hair's outer coating, known as the cuticle. Once those scales are opened, colorant molecules from the dye are able to enter the hair, chemically-altering it so that it changes color.
Needless to say, having their cuticles repeatedly pried open makes hairs fragile. The colorant molecules can also be very toxic and because they're so small, it's possible for them to pass through the skin and enter the body, causing adverse reactions.
Graphene, on the other hand, is non-toxic and chemically inert. Huang's dye incorporates tiny sheets of the material, which wrap themselves around the individual hairs to create an even coating that gives those hairs the natural color of the graphene (different shades of black and brown are currently possible). Non-toxic polymer binders in the dye keep those sheets sticking to the hairs for at least 30 washes, preventing the color from fading.
Not only are the graphene sheets non-toxic, but because they're much larger than the colorant molecules used in regular dyes, there's no chance of them passing through the skin. Additionally, because graphene has anti-static qualities, the dye should prevent flyaway hair. And as an added bonus, the process of applying the dye to the hair and then drying it reportedly takes less than 10 minutes.
The cost of the dye shouldn't be a huge issue, as it utilizes an inexpensive imperfect type of graphene known as graphene oxide. And because graphene is electrically conductive, other possibilities present themselves.
"People could apply this dye to make hair conductive on the surface," says Huang. "It could then be integrated with wearable electronics or become a conductive probe. We are only limited by our imagination."
A paper on the research was recently published in the journal Chem.
Source: Northwestern University