Scientists in Illinois have developed a new environmentally friendly hair dye that delivers stunning black locks. The raven color comes from a form of black carbon — the same basic ingredient as in soot and pencil lead.
Traditional hair dyes are made up of a lot of harsh chemicals. Each performs a certain function. For example, the job of bleach and ammonia is to pry open cellular “scales” on the outside of the hair (the cuticle). This allows the dye’s color to enter the hair strands. A chemical reaction then occurs which produces more color.
The graphene-based hair dye has worked its magic on a lock of blonde hair (top). The dyed hair (bottom) now has an even, rich, black color.
But the pungent smell of hair dyes leaves you wondering what type of damage it might do to the scalp and hair. In fact, those chemicals can make hair so fragile that the strands can easily break. Dye ingredients also can dry out the skin. Some scientists worry that hair dyes might even pose more serious risks. Animal studies, for instance, have suggested some ingredients might cause cancer. And some of those chemicals can enter the body as inhaled fumes or by passing through the skin. (To date, however, no studies have confirmed that using these dyes poses health risks to people.)
The new dye uses none of those harsh chemicals, notes Jiaxing Huang. He works at Northwestern University in Evanston, Ill. As a materials scientist, he looks at how to develop new materials based on their physical and chemical properties. He was intrigued by graphene [GRAA-feen]. It’s made from nothing but carbon atoms (and won its initial investigators the 2010 Nobel Prize in physics). This material’s carbon atoms are all locked together into flat sheets, each a single atom thick.
Graphene also binds well to hair. So this dye will last a long time without fading — through more than 30 washes. That 30-wash durability is a minimum for today’s store-bought hair dyes.
Huang explains why graphene-based hair dyes will last as long, if not longer, than store-bought hair dyes. He likens the color particles in traditional hair dyes to tennis balls. They don’t easily stick. That means that with each shampooing, some can easily roll off of strands of hair, bit by bit. Graphene’s flakes are instead like itsy bitsy wet paper towels. Each can wrap around a hair shaft and really stick.
Culled from ScienceNewsforStudents