IRA FLATOW: This is Science Friday. I’m Ira Flatow. Coming up later in the hour, a look back at some of our favorite science books of 2021. But first, something that may seem familiar this time of the year. What is it, you open up a holiday card and out pours a little unexpected surprise– glitter. And that glitter will seemingly be with us forever, hugging your sweater, covering the floor. But glitter doesn’t just stop there.

It washes down the drain, travels into the sewage system and the waterways. And since it’s made from microplastics, you know it’s never going away. So as it turns out, all that glitter is not gold, or even biodegradable. But what if you could make glitter that was biodegradable?

Silvia Vignolini, Professor of Chemistry at the University of Cambridge has done that, developed eco-friendly glitter made out of plants. Professor Vignolini, thanks for being with us today. Welcome to Science Friday.

SILVIA VIGNOLINI: Thank you for the invite.

IRA FLATOW: Tell us why exactly glitter is so bad for the environment.

SILVIA VIGNOLINI: The glitter itself is a composite material. So you have a layer of metal, and then on top of it, the very cheap one, you have a layer of plastic. That is where you embed some pigmentation. And the combined effect of this metal layer with this top layer that has this pigmentation gives you this glittery effect, this metallic effect. This is a typical example of a microplastic, because the size around, the size of a few tens of microns depending on what type of glitter you consider. But the most wanted, the most available, and the one most widespread often have this type of problem.

IRA FLATOW: There is a lot of glitter that’s marketed as biodegradable, or eco-glitter. What’s in that stuff?

SILVIA VIGNOLINI: This is actually a little bit better. Because instead of having a plastic like that is not degradable, you might find some bioplastics. But you still have the problem of this multiple layering. So you have still a material that is a composite. And therefore, you have challenges in recycling, especially if you don’t recycle it properly.

IRA FLATOW: It’d be hard to recycle glitter. Even if you wanted to, you can’t do it.

SILVIA VIGNOLINI: Yes, because it ends up everywhere.

IRA FLATOW: [LAUGHING] And what about mica? It’s also sparkly. And it’s in a lot of makeup and other beauty products. Is that better for the environment?

SILVIA VIGNOLINI: Mica is not necessarily bad itself. The only problem of mica is the way that is resourced. So that if you have an ethically resource to mica, because often, they exploit child labor to produce mica. But obviously, like company are becoming more and more aware. So they try to resource it in more ethical ways.

But they still have a little bit. The problem that is a highly energy intensive process, because you really need to make really small flakes out of rocks at the end of inorganic materials. But it’s based on mica. But it’s not only mica. So mica is one of the layer of the component. On top of the mica, you might have other materials, and often also have plastics, polymers.

IRA FLATOW: Who thought that glitter was so complex to make?

SILVIA VIGNOLINI: In order to understand why it’s complex to make them, it’s important to understand the phenomenon that is behind what makes glitter glittery. So generally, when you have a coloration, a color, like the color that you use to paint a wall or to color your clothes, these are traditional pigments. And this pigment essentially, their coloration, their appearance depends on the chemical characteristics of the material that you have. But the color doesn’t change in function of the angle.

So in order to have this metallic sparkling effect, you can do in two ways. One is to use a metal, because metals, they are shiny. And the way that they reflect light with respect to pigment, it’s really different. That’s why also you can have a mirror. They behave as a mirror, metals. Another way is what you call structural colors. They don’t come from the interaction of the light with the chemical characteristic of the material, but with the physical characteristics of the material.

IRA FLATOW: That’s like butterfly wings, things like that.

SILVIA VIGNOLINI: Exactly. Exactly. So you need to have a structure on the order of few hundreds of nanometers that interact with the light with the phenomenon that is called interference. And this gives rise to this vivid color that are really metallic and really shiny.

IRA FLATOW: So let’s talk about your achievement now. Given the background of all of this glitter, you’ve made a new type of glitter that avoid some of those environmental issues using cellulose from wood pulp. What made you think to try and make glitter from plants?

SILVIA VIGNOLINI: OK. So we saw in nature that cellulose can be used to make colors. That was really my inspiration when I started to work on this system, if you want, almost 10 years ago. In fact, we discovered that there are several types of plants that can use the cellulose fibers that are the same fiber that we talk about that you have a diet that is rich of fibers.

So we have observed in nature this type of coloring in several types of plants, fruits, but also leaves. So it’s a really common architecture. And it’s a trick that plants use to make color when they cannot make it with pigmentation. So we thought, OK, plants can do it. Maybe we can try ourselves as well.

IRA FLATOW: So how did you extract the cellulose and make it into glitter?

SILVIA VIGNOLINI: So what we use from the cellulose, from wood pulp, or any type of plaint’s biomass that can then be also like– we also extracted from grape skin from the waste from wine industry. Or we can also extract it from cotton linters that are the piece of cotton that comes from– that cannot be interwoven into yarn. And all these small bits and pieces of cellulose, you can extract what you call the crystalline part. So it’s a type of material that we call cellulose nanocrystal.

And nicely enough, when you use this material and you put them in water in the right condition, they can behave as so-called liquid crystals, so the same type of chemical that you have in computer display to make the display. This particle, they have a similar behavior. So they can form layer structures that are also similar to what you see in the plants that can interact with light to create this coloration. So at the end, we simply use this part of the cellulose, and exploit this principle that is a spontaneous process that the material does. So it’s called self-assembly.

IRA FLATOW: Hm. But is it as sparkly as the real stuff, as the synthetic?

SILVIA VIGNOLINI: Yes, it is really sparkly, because it’s similar. The concept is the same of the one that you see in the butterfly wing, or in the feathers of a peacock. Now, the color doesn’t depend on the material, but depends on the physical structure. As soon as you are able to physically structure the material in the right way independently from the material that you used the chemical composition, you can get really bright color.

IRA FLATOW: So what needs to happen before this glitter goes from your lab onto my shelf?

SILVIA VIGNOLINI: Well, lots needs to happen. So we got lots of interest lots from the media, and then obviously, many companies contacted us. Our technology if you want, is based on this self-assembly. And the self-assembly mechanism, especially using biomaterial, is not really well developed in industry as a process. Because it has also disadvantages.

It is slow with respect to conventional manufacturing methods that are used now to make pigment and glitter. It’s a bit slower. And therefore, as a technology, is a little bit disruptive with respect what is present today. So you first need to convince the company, the manufacturing company that it’s actually a process that it’s economically viable. Because at the end of the day, it’s sad to say, but I don’t know how many people would be happy to pay lots of money for buying glitter that is more sustainable.

IRA FLATOW: Yeah, so you have to bring the price down when you make it.

SILVIA VIGNOLINI: Exactly. You need to make the material that is compelling also from a point of view of economic point of view. And the raw material is not expensive, because it is cellulose itself. And actually, the fact that you can get it from waste, it makes it even more attractive. But the processing at the moment is expensive. And in order to really being able to sell it on a commercial level, there is a lot more technical challenges that needs to be addressed in question of producing it on a really large scale.

IRA FLATOW: Well, tonight I’m going to see a lot of confetti and streamers on New Year’s Eve coming down in Times Square and other places, and around the world. Is it possible to make all this stuff that’s going to be raining down biodegradable also just like your glitter material?

SILVIA VIGNOLINI: Yeah, it is possible. The question is like again, it’s a question of will and question of how much people that want also to invest, and they are ready to change this technology for something that is a little bit more sustainable. Obviously, you know, I think it’s also always important to remember that you are always creating an impact with what you disperse around, yes?

So you produce more waste. It’s true that even if it’s biodegradable, it’s better. But it’s still going to take some time to degrade. Yes, and it’s still going to probably affect the environment that you have around. So even if you have a material that is essentially inert, like cellulose, and it’s degraded by many different microorganisms, if you accumulate large amount, a large mass of one specific material in a place, you might [? alterate ?] the whole system of that specific area. You will have an environmental impact.

So my suggestion is, that we shouldn’t live our life of where we restrain ourself in everything, but we should also be a little bit more aware that everything that we do is impacting our environment. And we should try to limit to what is really necessary and trying to be more– or to use it, but in special occasion, and not be everything that is a consumer that then it goes in the bin. And because it’s [? written ?] bio, we are happy with it. And we don’t think about it anymore.

IRA FLATOW: Well Dr. Vignolini, we wish you great success, and hopefully, next New Year’s Eve we’ll be able to see biodegradable confetti, glitter, streamers, all that kind of stuff. Thank you for taking time to be with us today.

SILVIA VIGNOLINI: Thank you. Have a nice evening.

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