Anyone who’s swiped on a sparkly eyeshadow or used glitter for arts and crafts knows that those tiny, shimmering pieces are hard to clean up—in more ways than one. Glitter gets everywhere, and since most glitter is made of plastic, it doesn’t disappear. But scientists say they’ve now made a glitter completely out of plants that can actually biodegrade, without compromising any sparkle.
Though small, glitter can be a big environmental problem. When glitter is added to cosmetics, it often ends up getting washed off, and the microplastic pieces make their way into rivers and oceans. So-called sustainable glitters haven’t been much better. While some plant-based glitters do already exist, they’re usually wrapped in materials like aluminum or plastic polymer film in order to give them their shimmer, coatings that don’t biodegrade; or, they need perfect composting conditions to disappear.
Mica and titanium dioxide, minerals used in “natural glitters,” have their own issues: mining the former is a practice fraught with child labor; the latter has been banned in the European Union because of its potentially toxic, carcinogenic effects, especially if digested.[Image: courtesy University of Cambridge]Researchers at the University of Cambridge say their cellulose-based glitter solves all these problems, for a safer, sustainable sparkle. The first pieces of this glitter were made from wood-pulp, which the researchers detail in the journal Nature Materials, but any plant product with easily extractable cellulose could be used, like cotton or even a “waste product” such as mango peels, banana peels, or coffee bean skins, says Silvia Vignolini, a chemistry professor at the university and senior author of a paper. (And since it’s only made from cellulose, it can also be safely eaten, the researchers say.)
To get their cellulose glitter to give off that iconic, multicolored twinkle, they didn’t add any plastic coatings or aluminum layers. Instead, they used a process called “structural coloration,” in which microscopic structural surfaces bend light waves in such a way that they produce pigments. Structural colors can be seen in nature, like on an iridescent peacock feather or the metallic-looking blue ofmarble berries.“The cellulose nanocrystals are organized in such a way that they can make color,” says Benjamin Droguet, also from the school’s chemistry department and first author of the paper. The nanocrystals form a helicoidal structure, meaning the layers rotate as if arranged in a spiral. Think of it as a staircase, he says. “The way to control the color is by simply changing the size of those helicoids, so we can imagine a staircase with levels that are different distances from each other. The larger the features, the longer the wavelengths of light that will be reflected,” which then changes the colors that we see.
The cellulose particles they used from wood pulp spontaneously form these structures through a process called self-assembly: the cellulose crystals align, and then twist. But to actually turn this into glitter, the researchers had to create large-scale cellulose films, and they did that by packing cellulose into water, As the water evaporates, it forces the materials to contract, which prompts that self-assembly into those spiraling, light-reflecting colors. They could then grind that film of colorful cellulose down into tiny particles of glitter. Because the only ingredient is plants, no matter what happens to the glitter, it will eventually biodegrade.Recognize your brand’s excellence by applying to this year’s Brands That Matter Awards before the early-rate deadline, May 3.