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Graphene hair dye offers alternative to harmful chemical dyes

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Researchers at Northwestern University in Illinois have discovered that graphene can be used as a permanent hair dye which is non-toxic, anti-static and which does not chemically alter the hair.

Graphene – an atom-thick sheet of carbon atoms – has superlative physical properties. Since its discovery in 2004, much excitement has surrounded its potential electronic and mechanical applications. However, according to researchers at Northwestern University, it may also prove valuable in the beauty industry.

Dyeing hair often damages it irreparably, particularly when combined with additional bleaching. This is because commercial dyes tend to use harsh chemicals such as bleach and ammonia to “pry open” each hair’s scales before inserting a colorant, then triggering a chemical reaction to produce more colour. This damages the hair, and involves a number of toxic molecules that can seep into the skin.

As an alternative to these chemical dyes, the researchers used a dye containing graphene oxide flakes. Graphene oxide is a cheap and imperfect derivative of graphene that is far more accessible than perfect graphene.

These flakes function as tiny sheets which wrap easily around strands of hair.

“It’s similar to the difference between a wet paper towel and a tennis ball,” said lead researcher Professor Jiaxing Huang, comparing graphene sheets to other pigments. “The paper towel is going to wrap and stick much better. The ball-like particles are much more easily removed with shampoo.”

Hair dyed black with graphene

Jiaxing Huang, Northwestern University

Image credit: Jiaxing Huang, Northwestern University

This graphene-based dye exists in black and various shades of brown, and can last at least 30 washes without fading, meaning that it could be formally recognised as ‘permanent’.

The geometry of these atom-thick flakes also means that they are less likely to be inhaled or pass through the skin barrier, as they are far larger in surface area than the particles used in commercial hair dyes.

“Our hair dye solves a real-world problem without relying on very high-quality graphene, which is extremely difficult to make,” said Huang. “I feel optimistic about this application.”

In the future, he says, a graphene-based hair dye could be manufactured in a wider range of colours or, more excitingly, make use of graphene’s other extraordinary properties, such as its extremely high electrical conductivity.

“People could apply this dye to make hair conductive on the surface,” he added. “It could then be integrated with wearable electronics or become a conductive probe. We are only limited by our imagination.”

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