How do stickers stick?

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Sometimes they're faces or flowers. They can be unicorns or price tags. Some are sparkly. Others glow in the dark. Some of them even smell. Mmm, this one's blueberry. We're talking about stickers and there's a million and one uses for them. From labeling groceries and decorating water bottles. To wearable name tags or even patching up holes inside our bodies. So imagine a patch and then the surgeon presses it onto the tissue and it sticks to the tissue. So it's kind of like an internal bandage. That's sticker scientist Phil Messer-Smith. We'll hear more from him later. Plus we'll tell you how stickers do the one thing they're most famous for. Stick to stuff. So tag along for this episode. Stick with us. Don't peel away too soon. Hey, Sandin, whatcha doing? You know I love it. The fresh air. The dirt between your fingers. The stimulating conversations with worms. First modernism is a deconstruction of the grand centrality sought out by previous generations. You said it, were you? 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Help us grow more beans of brains on, squashes of smash boom best, and fruits of forever ago. Thank you. Bringson! Bringson! You're listening to Brains on. I'm Molly Bloom, and my co-host today is Amira from Indianapolis. Hi, Amira. Hi, Amali. We're here today because you sent us a question that really stuck with us. Yeah, I asked, how do you stick your stick? Such a good question. Stickers are really everywhere. And the science of how they work is super cool. So Amira, I'm wondering, do you have a favorite sticker, like on a notebook or anything? I decorate any treasure boxes I have with stickers. Mm, nice. What's your favorite sticker right now that's on a treasure box? Probably a 3D bird. Ooh, is it kind of like fuzzy or like what's 3D about it? It like pops up. So how about a bumper sticker? If you could design a bumper sticker to tell the world about you, what would it say? It would probably be one of my favorite books because I love reading. Ooh, what is one of your favorite books? My favorite series right now is Keeper of the Lost Cities. So do you have like friends who are really into stickers who have stickers like on everything? My sisters. Where do they put their stickers? Same places, water bottles, books. I feel like there's so many stickers now when I go places like they're so fun and colorful and there's like when I go to the bookstore especially I feel like there's always really cool stickers and I'm always like I want them but I don't really know where to put them sort of my problem. I do have a great sticker that my friend gave me inside of my planner that just says fart jokes because she knows me really well. So the best part of stickers is that they stick. Yeah, stickers, great name, tells you exactly what they do. But the name doesn't tell you how they do it for that let's use our handy, dandy, zoom ray. It lets us zoom in on something and see what's going on up close. Zoom ray, another great name, tells you what it does. Yep, Amira, can you please grab some stickers? How about these flying goat ones? They've got Peggy's wings and they're burping rainbows. Super random, totally love it. Now stickers have a sticky side and a non-sticky side. Let's zoom in on the sticky side. Just got to power up this ray. Perfect, let's zoom. Whoa, so that's the sticky side of the sticker up close. Sure is. Look at those ropes. Those aren't ropes. Those are actually long molecules. Those are a group of atoms, which are the building blocks of everything. Oh, right. If an atom was like a single Lego brick, molecules would be like a bunch of Lego bricks stuck together. Exactly. And just like you can build almost anything out of Lego, the world is built out of atoms and molecules, but both atoms and molecules are way too small to see with just your eye. That's why we need the zoom ray. The molecules used on stickers are called adhesives. That's basically a fancy way of saying they're good at sticking to things. So we are looking at adhesives aka sticky molecules. Make sense? Yeah, but here's what's special about these sticky molecules. They have a nice bounce of being able to flow like a liquid and stay stiff like a solid. Let me show you. This is a piece of paper up close. Whoa, it's actually really bumpy, like a woven basket or something. Yeah, those are the fibers of the paper. Up close, you can see how rough paper is, but when we zoom out, it just looks flat. Wow, zooming is so rad. Yeah, it is. Those bumps and dips on the paper are really important for stickers. In fact, most things you put stickers on have bumpy surfaces when you look at them up close. When we place the sticker on a surface like that, the molecules flow into the bumps and dips. Now, watch as we press the sticker into the paper. Ooh, the sticky molecules are filling up those spaces. They're flowing into them kind of like a liquid. Exactly, but unlike a liquid, once they get in there, they stay put. They don't flow back out. So more like a solid. Yes, these sticky molecules need a balance of being able to flow like a liquid and stay put like a solid. And that's also why the key to making sticker stick is pressing them. Oh, so like how you press a sticker into paper with your finger. The more you press, the better it sticks. Yes, pressing helps push those sticky molecules deeper into those nooks and crannies so they can really hold onto the surface of something. Now, let's zoom out. Wow, now it's just a very colorful flying goat sticker on a piece of paper. Who knew there was so much going on up close? It's always a whole new world when you zoom. Coming up, how do scratches and sniff stickers work? But first, I've got something that'll stick in your ears. It's the... Amira, are you ready for the mystery sound? Yes, I am. Here it is. What do you think? I don't know. That is a very strange sound. It really is. I think we should hear it again, maybe? It sounds like a dump truck and then dumping out a bunch of nails or something. Ooh, I like that idea. Somebody said it sounded like water, maybe? Yeah, it did. I couldn't figure out what the water would be though. Yeah, maybe a dump truck full of water. Yeah. Hmm, okay, okay. Well, we will hear it again, get another chance to guess and hear the answer at the end of the show. Keep an ear out for that. We are working on an episode all about how we divide up generations. You and all the kids you know are in the same generation. Which name would you give your generation? Right now people are calling you Jen Alpha, which is kind of boring. It basically just means generation A. I think we can do better. So Amira, what would you call your generation? I would call generation the coronal since we went through coronavirus or whatever it was called. Yes, I think that's a really good name. That was a big deal. How, what grade were you in when that happened? I think I was in Sinkit and then Third grade. Well listeners, please write to us and tell us what you think, what would you call your generation? You can head to brainson.org slash contact and send us your recording. Today's episode is sponsored by Bombus. It's the time of the year we think about, hmm, what if I got to do differently this year? Maybe I'm going to read more. Maybe I'm going to work out more. Maybe I'm going to learn a new skill, but really at the top of my list is number one, to get comfy. And that's where Bombus comes in. They're bringing a serious comfort to all my everyday go-to's. The all new Bombus sports socks are engineered with sport-specific comfort for running golf hiking, skiing, snowboarding, and all sport. This year I'm going to walk my dog more, longer walks, better walks, and these socks are going to help me stay comfy while I do it. Here for all my other resolutions like going to the bookstore and picking out more books to read, I'm going to wear my new squishy Saturday-sweighed slip-on shoes, which are super comfortable for being on the go. Head over to bombus.com slash family 26 and use code Family26 for 20% off your first purchase. That's B-O-M-B-A-S dot com slash family 26, code Family26 at checkout. Welcome back to Brains on I'm Molly. And I'm Amira. And we're talking about the science of stickers. Stickers are what's known as pressure sensitive adhesives. Because use pressure like pressing them down to make them adhere, which is just another way of saying stick. When you press a sticker, the sticky molecules on the back flow into the nooks and crannies of a surface like paper, then those molecules hold on tight. But not all things stick this way. Like classic white glue. For that, you put the glue on wet and it sticks as it dries out. The liquid leaves and it creates a sticky bond. Hot glue guns work squirting out a melty goo that sticks as it cools down and gets hard. In this case, the bond is made strong as heat leaves the glue. There are lots of ways to stick, but what about sniff? Amira, do you like scratch and sniff stickers? Yes, I do. Me too. So if you could have a pack of stickers with any smell in the world, what would it be? I would make a pack of stickers that smell like baked goods. Like a variety pack of different kinds. Yeah, like cookies and brownies. Yes. I would buy those stickers and put them all over everything. Excellent idea. So the cool thing about scratch and sniff stickers is, you know, they stick just like a regular sticker. But the smell comes from the other side, the non-sticky side. To make one, first you need a smelly chemical. Scientists can make chemicals with all kinds of smells. From banana to blueberry to root beer and chocolate chip. Then you put that smelly chemical in a tiny little capsule or container, like really small, like picture a teeny tiny little bubble. Those tiny little smell-filled bubbles are added to the paper used for the sticker. When you scratch that paper, you are actually breaking those tiny bubbles open. That lets the smell out. Each time you scratch and sniff, you're breaking more and more of them. But there are a lot. So the smell can last a pretty long time. Since we're talking stickers, I asked some of our friends to stop by with their sticker collections. Come on in, friends. Hey, everyone. Why, hello. Hi. Hey, Sandin. Hey, Mark. Oh, hi, Bob. Mark, can we see your sticker collection first? Hmm, this is embarrassing. Are you carrying a box of clocks? I thought we were supposed to be showing off our ticker collections. I brought clocks, turn signals, neutrinomes, but no stickers. Barry! Oh, Mark, I see. What about you, Sandin? Oh, I definitely have stickers. I collect the coolest, the flashiest, the most allowance-costing stickers ever. Creature creeper stickers! Creature creeper stickers? You know, it's stickers made up of monsters with different powers. Like, oh, this one's slitherish, part snake, part licorice. He's irresistible. This one's blancho mirage. She disappears when you get too close. Oh, and this is the rarest of all. Sneak it you! Do you mean Pikachu? Never heard of her. No, sneak it you is a sneaker with things. This sticker was so expensive. Wow. How much? 599. Wow, that's a great price. I have it here. See? Bob, is that your sticker collection? Yes, Molly. I collect price tag stickers. Check it out. I have 225, 650. I even have 1999. That one took forever to find. And guess how much it cost? $19.99. Wow, you're good. It even came with a free bark attached to it. Bob, you collect price tags? That's not a sticker collection. No, no, no. You need stickers with colors, with patterns, with monsters of varying sizes and abilities. Do I like my stickers? No, no. You need help starting a real sticker collection. Do not worry, Bob. I have an idea. Well, thanks for stopping by everyone. Yeah, nice stickers and tickers. See you all later. Later, skaters. Bye. You're on the flip side. This seems like a good time to check our mail bag, right, Amira? Yeah, you know, stamps are just stickers that pay for mail. So mail is really on theme. You are so right. Let's do it. Hey, your favorite sand in here with mail. Let's fire up the old inbox and see what we've got. Oh, a question from listener Hang Yu in San Jose. Why do people still use metal as utensils, even though it gets hot so easily? Hmm. Great question. Well, I was taken a spoon out of the dishwasher yesterday and it nearly melted my fingerprints off. It was so hot. Love your curiosity. Okay, let's check out this mail. It's from Cohen and Scarlett. They say there are so many words that just add ER to the end. Hotter, colder, warmer, sunnier, cloudier. Why not fun? Why isn't fun or a word? It would be much more fun if fun or a word. Okay. I 100% agree. Winter forever. Oh, it's speaking of fun. We've got a joke here from William and Charlie. What cars are the best students? The honor roll cars. Haha. Hello, Arias. That was good. Okay. Well, thanks y'all for the mail. Keep it coming. Send your jokes and random thoughts to brainson.org slash contact. See ya. Did you know you can listen to brainson, smash boom best and forever go all without ads? Just join Smarty Pass. Members also get invites to virtual events, our book club and more. Go to SmartyPass.org to sign up. Thank you so much for keeping our shows going. Brain, brain, brain. This is brainson with Molly and Amira. And we're talking sticky, sticky, stickers. Members, as we know them, have been around for almost 100 years. In the early days, they were mostly used to label things. But over time, people figured out you can put them on car bumpers, suitcases, you can even use them to decorate stuff. And they became fun and collectible. Today, you can find a sticker of almost anything, even flying rainbow burping goats. But there are things that you use all the time that you probably don't realize are stickers. Juice boxes, those little cartons that contain juice are actually usually between five and ten layers of material. Each of them stuck together using an adhesive. That's Philip Messerschmiff. He teaches about the science of things like stickers at the University of California, Berkeley. He's especially interested in the future of stickers. For example, his lab is working on stickers that can be fully recycled. Right now, we can't easily recycle things with sticker glue or adhesives on them. But maybe soon we'll be able to. Another cool thing he's working on, stickers that can stick inside our bodies. So imagine you're a surgeon repairing a hole in a patient's intestine. The intestines are a part of our gut. It's where food goes after it's broken down in the stomach. And it's critical to actually seal that hole very, very carefully because the bacteria in the intestines, if they get out and into your body, the rest of the body, it can be very dangerous situation. Stitching soft material like the intestines can be really tough. But what if you could use a sticker? So what the doctor might do is they take a patch that looks kind of like a band-aid and they might press it onto the tissue and cover off and block that hole so that no bacteria can escape into the body. Of course, those kinds of stickers need to be waterproof because it's wet inside our bodies. And they have to be made out of materials that won't make us sick or hurt our bodies. So it's a challenge. But luckily, scientists like Philip are working on it. Thanks, Philip. So stickers are everywhere. They have a million and one uses and we keep dreaming up new ways to use them. Stickers for the win. Woo! Grains on the top. Bob, hey, it's your lucky day. It is. Oh, boy. Yeah, because I saw how boring your sticker collection was. So I got you this. You're a very own pack of creeper creature stickers. Oh my grapes. Really? This is absolutely amazing. Sandin, it's exactly what I need. I mean, yeah, it's a pretty cool pack. It's pretty average, but I mean, yeah, it could be some cool stickers in there. Three, ninety-nine. I've been looking for that price tag for years. I can't believe you found it. I need to put this in my collection right away. Wait, wait, wait. The gift was the pack of stickers. Not the price tag. Aren't you going to even open these? No time. Thanks a million, buddy. You're a true hero. The best. I can't believe I got three, ninety-nine. Amazing. Three, ninety-nine. The price so fine. It's mine. Mine. Mine. Mine. Stickers are also called pressure sensitive adhesives, because you press them to make them stick or adhere. They have a special glue on one side that can flow into the microscopic nooks and crannies of a surface like paper. That glue then stays put, holding onto that surface and making the sticker stick. Scientists are working on new kinds of stickers that are better for the planet, and stickers that can be used as band-aids inside our bodies. That's it for this episode of Brains on. This episode was produced by Molly Blue, Mark Sanchez, and Sam Dintaten. We had engineering help from Adam Gross, special thanks to Aaron Cecil and the whole family, the Ken Taborski, and the Code of the North for all of their website help. Amira, are you ready to go back to that mystery sound? Yes, I am. Okay, here it is again. Hmm. What are your new thoughts? Kind of also sounded like a pressure washer. Oh, interesting. Yeah, the pressure washer is something that clean stuff with a really strong spray of water. Yeah. That's a good guess. Yeah, it starts quiet and gets loud. Yeah. It's quiet again. I'm going to go back to your dump truck idea. I think you want something there. I'm going to go back to dump trucks spilling out jelly beans. Should we see if we're right? Yeah. All right, here is the answer. Hi, my name is Liz. I'm a little bit old, and I live at Chicago. My mystery sound was a volcano. It was made from baking soda and vinegar. Have you ever made a volcano at home? Oh, wow. Wow. Have you, Amira? I have not. Oh, my gosh. That's why we didn't recognize it. I like that he asked us a question. Oh, that was really sweet. That was tricky. Have you seen one of those volcanoes before? I have. So, yeah, you pour vinegar in, and then it fizzes up and explodes. High fives to us for trying our hardest. Now, it's time for the brains honor roll. These are the incredible kids who keep this show going with their questions, ideas, mystery sounds, drawings, and high fives. Toby from Newport, Newspiriginia, Parame from Shanghai, China, Ella from Colorado, Springs, Colorado, Owen and Evelyn from Ophalen, Missouri, Leo from Folkstone, UK, Noah from Georgia, Theo from Brooklyn, New York, Miles from Ohio, Harris from Mobile, Alabama, Thiago and Cortes from Fountain Valley, California, Finn from Mount Washington, California, Leo from New York City, Martha from Concord, New Hampshire, Harrison from Winnowsky, Vermont, Josephine from Arlington, Heights, Illinois, Viadora from Lisbon, Portugal, Lucas from Baldwin, Missouri, Isabella from T. Burrow in California, Baxter from Seattle, Austin and Lucas from Taipei, Taiwan, Kylon from Washington, DC, Ben from Cincinnati, Hazel from Oak Creek, Colorado, Joshua from Perifax, Asian, Virginia, Leo from London, Washington, Donno from Fort Lauderdale, Florida, Leo from Melbourne, Australia, Martina from Sydney, Australia, Adrian from Foster City, California, Eva and Emma from Thetford, Vermont, Arthur from Brooklyn, New York, Elizabeth from Lincoln, Nebraska, Yasman from Ottawa, Kylian and Beckett from Niska, United New York, Cristiana from Yonkers, New York, Reyna from London, England, Hugo from Frankfurt, Germany, Dexter from Columbus, Ohio, Haley from Caldwell, Idaho, Zade from Pingera, Australia, Rachel from Durham, North Carolina, Rowan from Oakland, California, Aiden from Victoria, British Columbia, Claire from Boulder, Colorado, Kaitlyn and Graham from Lombard, Illinois, Elon from Jakarta, Indonesia, Claire and Samuel from Pennsylvania, Sebastian from Berkeley, California, Cobain from Vancouver, Davis from Canton, Georgia, Jonah from Port Washington, New York, Cali from Victoria, British Columbia, Alan Nore, Josephine Reagan, and Charlotte from Michigan, Griffin from Santa Rosa, California, Anton from Duluth, Minnesota, Alia from Perth, Australia, Maggie from Vancouver, Washington, Alan Nore, and Henry from Victoria, British Columbia, and Lyra from Massachusetts. Great time of life. Tune in next week when we'll have an epic battle in the insect world. Thanks for listening.