Nanocrystal glitter keeps the sparkles without the polluting plastics

Glitter is used everywhere from kids' craft projects to cosmetics, but beneath its shiny surface is a dark side.

Key points:Traditional glitter is made of plastic, and while there are some eco-glitters on the market they are not fully made out of plant materialsNow UK researchers have made a new type of glitter made out of a cellulose nanomaterial they say is truly biodegradableIt is the first time that they have been able to produce the glitter on a commercial scale

Beyond being annoying like a party guest that refuses to go home, these tiny sparkles are traditionally made of plastic and contribute to pollution.

As a result, scientists have called for it to be banned, and it's no longer used by organisations such as the Sydney Gay and Lesbian Mardi Gras.

But there may be an alternative in the future with the creation of a new nanomaterial inspired by nature.

A team of researchers from the University of Cambridge has found a way to turn tiny crystals of plant fibre known as cellulose into glitter on a commercial scale, they report in the journal Nature Materials.

"The advantage of what we have is it is 100 per cent made of [natural] cellulose," said Silvia Vignolini, the study's senior author.

close up of blue and gold glitter
Blue and gold glitter made out of cellulose nanocrystals are just as vibrant as glitters made out of plastics.(Supplied: Benjamin Droguet)

There are already a number of "eco glitters" on the market, but while they can contain some cellulose, they are not fully biodegradable, Professor Vignolini said.

Last year, another research group from the UK found that both conventional and alternative glitters currently on the market can have ecological impacts on freshwater environments.

"The other eco-glitter you find contains a small metallic layer and then they can have another polymer that can be cellulose that contains pigments inside," she said.

The metallic layer in these products, which acts like a mirror to give the pigment its shine, may be made out of aluminium.

Pigments may contain layers of the mineral mica, which is often mined in developing countries, and titanium dioxide, which is banned in Europe and under review in Australia for use in food products in the wake of health concerns.

So how does this new material work?

Most things around us are coloured using pigments, which reflect different wavelengths of light in a scattered way so they don't shine.

The new material is made out of nanocrystals sourced from cotton or wood that are configured to focus light in a particular direction, in a process known as structural colour.

Close up of a peacock feather
The fibres of peacock feathers are arranged to produce vibrant colours.(Piqsels)

"So when you look in one direction you observe one colour, but then if you shift direction the colour changes like in the feathers of a peacock," Professor Vignolini explained.

To achieve this effect, the team of researchers led by Benjamin Droguet added water, salt and another type of soluble cellulose to the tiny particles to help them stick together, and make them reflect different wavelengths of light.

three vials of glitter in fluid
The same cellulose nanoparticles in three different solutions. Higher water content makes the particles swell and changes the colour we see.(Supplied: Benjamin Droguet)

The mix of wet pulp was rolled out into a thin film that was dried out.

"When you evaporate the water, the particles have less volume so they are forced to interact with each other and form the structure [and the colour]," Professor Vignolini said.

The film was then heated up again and crunched down to make glitter, which held its colour for a year without fading or dissolving when it was added again to a liquid such as a drink.

How biodegradable is it?

Professor Vignolini said their final glitter product still needed to undergo testing for its biodegradability and toxicity.

"We haven't done [testing] yet on the glitter, but it has been done on the cellulose nanocrystal [and] it seems it is biodegradable, it's not toxic and it ticks all the boxes," she said.

Glass of champagne with sparkles in it
The cellulose nanoparticles did not dissolve when they were put into a drink.(Supplied: Benjamin Droguet)

Jennifer Lavers, a marine ecotoxicologist at the University of Tasmania, says it's encouraging that people have started talking about the harm glitter does and are thinking about alternatives.

But, she says, the study from last year shows we need more research to understand how glitter products affect the environment.

"I think we need to be careful as scientists, that really anything we are putting into habitats in the environment, whether it's cellulose and fully biodegradable or otherwise, it could be detrimental for some species," Dr Lavers said.

"Literally anything can become a pollutant; even too much fresh water in a marine ecosystem."

The concept of whether something is biodegradable can also be a grey area.

"It's unclear under what conditions something can be biodegradable. Does it need certain bacteria, does it need extreme heat, what does it biodegrade into?

"Often products labelled as biodegradable actually require very specific conditions to meet the criteria of biodegradability, and those criteria are not going to be met in the stomach of a mussel or a clam or a seabird or a fish."

Images of cotton, wood and spinifex with correlating microscopic images of their nanofibres.
Cellulose nanoparticles can be created from any plant material including cotton, wood and grasses.(University of Queensland: Nasim Amiralian)

Nasim Amiralian of the University of Queensland works with a different team creating biodegradable and sustainable medical textiles and packaging out of cellulose fibre from grasses.

She says while some types of plant-based materials such as polylactic acid sourced from corn starch or sugar cane are not biodegradable in marine environments, the type used in the new study is.

"The material Silvia is using is basically paper. You can degrade paper in home composting," Dr Amiralian said.

But the time it takes for the end product to degrade may change when nanoparticles are modified.

"If you compare it to a leaf, a leaf is going to degrade faster than these materials," she said.

But no special treatment was needed to break them down into water and carbon dioxide, she said.

How long before it's commercially available?

While the team had previously achieved this effect in small quantities in the lab, this was the first time they had created large strips of material.

Two hands hold a strip of shimmering material
The team created 1-metre strips of glitter film using commercial techniques.(Supplied: Benjamin Droguet)

"The beauty of this work is that they are using already established processing that's been available for different industries," Dr Amiralian said.

But it's still got a way to go before we see it on our shelves. 

The team hope to create a company and look at how to produce larger volumes of the material.

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They are also investigating questions around the possibility of using renewable sources of cellulose to make the product sustainable, Professor Vignolini said.

"If you want to replace all of the pigment that is existing on the planet with this technology, how much [cellulose] would you need? Can you harvest it in a way without destroying the environment?"

While the experiment focused on producing glitter, Professor Vignolini hoped the process could one day be used more broadly to make environmentally friendly pigments used in everyday products such as paints.

"Sometimes I feel bad because I want to do something that has a good impact and I think there are better ways to save the planet than make more sustainable glitter," she said.

"But pigment is so embedded in our communication — if you can produce it in a more sustainable way that is not impacting the environment, I don't see it as a waste of resources." 

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Posted 11 Nov 202111 Nov 2021Thu 11 Nov 2021 at 9:00pmShareCopy linkFacebookTwitterArticle share optionsShare this onFacebookTwitterLinkedInSend this byEmailMessengerCopy linkWhatsApp

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