Episode Transcript Arpita: 0:10 Hi everyone. And welcome back to the Smart Tea podcast, where we talk about the lives of scientists and innovators who shape the world. How are you, Aarati? Aarati: 0:19 I'm doing pretty well, Arpita. How are you? Arpita: 0:22 I'm doing great. Um, happy 4th of July. Aarati: 0:25 Yes. Arpita: 0:27 It is uncharacteristically warm and summery feeling for the Bay Area. I have lived in San Francisco for a long time and I very strongly associate the 4th of July with being foggy because we tend to have very foggy summers in the city and then we get a lot of sunshine in September and October, but this year both Aarati and I are wearing tank tops and it's very warm in the bay, uh, which is pretty funny because this doesn't normally happen. Um, and I've had a very lovely holiday. I went camping, uh, just north of the city last night, which was actually really perfect because we finished work and then got to leave in the afternoon. And then spend the night. And then this morning we drove to Stinson Beach. We got there just before nine. Um, like we woke up in the morning, like camp, like whenever, like we Aarati: 1:20 You, you're early birds. I know. Yeah. Arpita: 1:23 We were early birds and we were also right there, like the campsite was like right there. And so then we just went over expecting there to not be that many people because it was before nine. The parking lot, completely full. We got one of the last spots. It was 8 45 AM. Aarati: 1:38 Oh Arpita: 1:38 People had already set up like all these tents, all their grills, their whole setup. And then by like 11:30, 11:45, I was like, I'm ready to go. Like, this is, this is what I needed. I got what I needed. I wanted to sit in the sun for a little while. And I'm ready to go home. Aarati: 1:54 Do they have fireworks over there? Like, what's the big draw? Arpita: 1:58 What's the end game? Yeah. Aarati: 2:01 Where I live, um, there's like a lake where they, or I don't know, lake might be too strong of a word, like a lagoon type area, where they, you know, shoot fireworks over and on the perimeter of that, it gets like people start putting up, you know, blankets and chairs and everything again, starting at like 8 o'clock. And then they just stay there the whole day until 9 PM when they finally shoot off the fireworks. So I'm just wondering, like, is there a... Is there something like that at Stinson Beach? Arpita: 2:31 I have no idea. I don't normally go to Stinson Beach, but we just happened to be camping nearby. So then because it was so nice, we were just like, Oh, let's go hang out at the beach for a little while. But I don't know anyway, but on our way back, so we're driving back down south, down highway one towards the city. Aarati: 2:48 Mm hmm. Arpita: 2:49 Miles, like miles and miles and miles of cars just waiting in line to drive north to the Stinson Beach entrance. And I was like, this parking lot is full. Like, I don't know what all of you guys are doing. Also, for people who are not from the Bay Area, Stinson Beach is not very big. Aarati: 3:07 Mm Arpita: 3:07 It's a pretty small strip of beach. And, most of the time in this part of Northern California, it's pretty cold and it's, you know, not really the type of beach weather where you would think about like laying on the sand. So normally it's like totally fine. It's usually people just kind of walking around, but there's not the real estate for the hundreds and hundreds of people who are trying Aarati: 3:29 why I'm wondering what are they all doing over Arpita: 3:32 No idea. But I guess my point is like, it's not a cool enough beach to warrant that sort of crowd. Aarati: 3:39 Yeah. No, that's like, I'm like, why don't they go to Ocean Beach or like Funston Or like, yeah, we're on the coast. There's so Arpita: 3:47 There's other Aarati: 3:48 so many. Yeah. There's so many other, like, what is it about Stinson Beach that everyone's like, this is. Oh my gosh, so weird. Arpita: 3:55 No. Logan and I are debating in the car being like, should we roll down the window and tell people that this party lot is full? Like that they're all waiting for nothing. Aarati: 4:05 Oh my god, just like be a good Samaritan Arpita: 4:08 I was just like, I would have bailed so long ago. Like, I don't, I don't even care. I would have done like an eight point turn and then just flipped it around on the highway. Like, I'm just like, there's no chance I'd be waiting in a line for something like that. Aarati: 4:19 At this point I'm like, even if there's like a spectacular fireworks display, it's not worth it. It's, you know, watch it on TV. I don't know. This is my whole, yeah, this is my whole family's mentality though. I firmly believe this is why I do nothing in life except sit at home because I'm just like, I can't be bothered, you know, going in lines like this. Yeah. Arpita: 4:41 Yeah. Anyway, so that's what's happening in the Bay right now. So if you're at home right now, you're not missing out. And I felt very smug about my plans because I was driving against the traffic and I was like, Aarati: 4:52 Good for you. Arpita: 4:53 I'm better than all of you. Aarati: 4:54 Yeah, exactly. Good for you. Yeah, totally. Arpita: 4:58 Yes, um, I'm very sorry if you waited in traffic. Um, I felt pretty good about myself. Um, anyway, that's my update on Bay Area traffic and Aarati: 5:08 Weather and traffic brought to you by Arpita. Thank you. Arpita: 5:12 Seriously, it's shit show out there. You're not missing out. Aarati: 5:14 It's amazing. No, but you're right though. I'm, I'm thoroughly enjoying the weather. My entire family is dying and I'm like, I'm warm for the first time in five years. This is amazing. I love it. Arpita: 5:26 Feels so nice. It's like perfectly warm. It's like not too windy. It definitely feels very summer and we don't normally get this during the true summer months in the calendar. So it's lovely. Um, but yeah, those are my updates. I think we're ready for a little story. Aarati: 5:41 Okay, so today's story is going to be an interesting one because my brother for a while now has been harping on me to do a polymer scientist and I've been resisting and resisting. He works on polymers, which is why he wants me to do one. And anyone who needs a quick reminder, polymers are molecules that are made of long, repeating units. They're long chains. And there are natural polymers like rubber, wool, cellulose and even your DNA, because that's like long chains of nucleotides. So that's a polymer. But then there's also synthetic polymers that we've developed to create all different types of materials like Teflon, polyester, latex, and styrofoam. And so because of that, there's all these different fields of studies around polymers. Especially from an environmental standpoint, because most synthetic polymers are made using petroleum. So how do we get away from that is a big question. And then another one is, how do we break down some of these polymer materials, like plastics that stay in our environment forever and ever. And so that's what my brother works on. And so that's just why he's been, you know, after me about like, you should do polymers. They're so interesting. Okay. So like, that's a quick orientation on today's topic, um, but as for the person that we're going to be talking about, we're going to be talking about a scientist who has been nicknamed The Queen of Polymers, Stephanie Kwolek, and you may have heard her name before because she invented Kevlar, which is the fabric that you still use today to make bulletproof vests. Arpita: 7:22 Yeah, yeah. And I love that we have a queen. Aarati: 7:25 Yes, a queen. So, Stephanie Louise Kwolek. She was born on July 21st, 1923 in New Kensington, Pennsylvania. I definitely said that wrong. New Kensington, Pennsylvania, which is a suburb of Pittsburgh. She and her parents, John and Ani-, I'm going to say this wrong too, Aniela, are I have practiced that so many times, I still can't get it right. Aniela. John and Aniela, or"Nellie", were Polish immigrants, and they had two kids, Stephanie and her little brother, Stanley. Her father loved to read books and newspapers and Stephanie always remembered him reading something when he came home from work. And he was an amateur naturalist. So he and Stephanie would go out and explore the woods around their home. They would spend hours observing the forest, collecting plants and looking at all the birds and frogs and insects around them. And Stephanie even kept a scrapbook of all the things that she collected from the woods, like pressed leaves, and flowers, and seeds, and even little bits of snake skin that she would label with her father's help. Arpita: 8:39 Whoa. Okay, kind of gross about the snake skin. What is the definition of a naturalist? Is it like if you're an amateur naturalist? Aarati: 8:46 Yeah, so. Arpita: 8:47 An interest in nature or is there more to it? Aarati: 8:50 He doesn't professionally study natural things like he doesn't professionally study nature, but he just enjoyed it very much to observe it and look at it. I think he actually worked at a foundry Arpita: 9:02 I'm now thinking that I feel like most of the people that I know who live in the Bay Area are probably amateur naturalists. Aarati: 9:08 Probably we have a pretty big outdoor culture. So yeah, absolutely. Arpita: 9:14 It's like every time I go on a hike and point out this like new flower that I find or something and I'm just like, Oh, this is blah, blah. Aarati: 9:20 So maybe just the, just the fact that he was in Pennsylvania made him a naturalist. If he was in California, he would have just been another normal guy. Arpita: 9:28 Have just been a Californian. Yeah, Aarati: 9:29 Yeah, exactly. Arpita: 9:31 We do live up to our stereotypes. Aarati: 9:33 We do. Um, but sadly when Stephanie was just 10 years old, her father died and I'm not sure what happened. Like I couldn't find out why. But he was very young. He was in his early forties. Um, yeah, but by then Stephanie had already inherited his love for science and the natural world. After that, her mother, who I'm going to call Nellie, who was a seamstress, had to care for Stephanie and Stanley by herself. And later in her life, Stephanie said that her mother probably was the one person who had the most influence on her career. She was, quote, an intelligent woman of great determination and strong will, yet she had a great sense of humor, end quote. And that is good to hear, because by now it was the 1930s, and The Great Depression was hitting the family hard. So Arpita: 10:24 And then also they don't have their father, Aarati: 10:27 Yeah, Arpita: 10:28 So that's like an added level of making things tough. Yeah. Aarati: 10:30 Yeah, even more so. And in the 1930s, being a single mom, having to work is really, really tough. So as a result, Stephanie didn't have a lot of toys. So she would spend her time copying her mother's sewing patterns to create new clothing designs for her paper dolls. And as she grew older, she even secretly started using her mother's sewing machine when she was out of the house to make actual fabric clothes. And she really enjoyed this. She really enjoyed designing and started to dream of going into fashion and becoming a famous designer and everyone would wear her clothes. Arpita: 11:09 That's so fun. I totally did this, by the way. I, my, Yeah, I totally did this. My mom really liked to sew, um, and she always talks about how when my sister and I were little, she would really, she like really loved making us like little clothes and making us dresses and, um, like all the things. And so she had a sewing machine and I never really got quite that good, but she definitely taught me basic stitches and like I know how to like hem and like, you know do buttons I'm just like small things but I used to totally do this with my dolls as like when I was very little would Try to take my Barbie clothes and then try to like make other clothes for them and other dress for them They were really ugly, but I totally did this. I'm sure she was Aarati: 11:52 it's Such a useful skill though, just in general, if you know, Arpita: 11:57 It definitely feels like a very worthwhile, very good bang for your buck skill. Aarati: 12:02 Um, but Stephanie's mother told her that probably her dreams of becoming a fashion designer, it wasn't going to happen for her because of Stephanie's personality. She was very particular and she needed everything to be exactly perfect. And. It wasn't really compatible with art and fashion, apparently. Okay. So one more thing you need to know about Stephanie, besides her being a perfectionist, was that she was gifted with an amazing memory. So she attended a really small public grade school. So two grades often ended up sharing a classroom. And because of this, Stephanie could hear what was being taught to the older students in the grade above her. And so for her, being in a classroom where two classes were being taught at once just meant that she learned things twice as fast. And she would annoy the older kids, especially the boys, because she would raise her hand for questions that their teacher asked, even though she was technically in the grade below them. And she knew the answers. So yeah, especially in math, the kids above her hated her. So Arpita: 13:11 That's pretty funny. Like, I kind of love that she did that, but it's honestly really impressive that besides of, beside her memory, she was able to process two streams of information at once. Like that feels like the more impressive part to me is like, you're able process two, you know, inputs. Aarati: 13:27 Yeah. And they, they didn't go into this, but I especially wonder if it's like you're being taught in history in one class, but then math in the other, and you're like processing both of those at the same time. That's. Arpita: 13:38 Yeah, that seems Aarati: 13:38 Yeah, that seems crazy. Um, so by the time she was in high school, Stephanie realized that her mother was probably right and she liked precision and that level of perfectionism didn't really work for her going into the fashion world. But that was okay because she really enjoyed math and science. She was really good at those subjects and they did give her the precision she enjoyed. So, Stephanie decided she wanted to go into science, and she wanted to help people. And so, naturally, she set her sights on going into medical school. Arpita: 14:12 Classic. Aarati: 14:12 But again, money was tight, it's the Great Depression, as I said, her mom is raising two kids on her own, and they just couldn't afford for Stephanie to go to med school. So instead, she decides to enroll at the Carnegie Institute of Technology, which is now Carnegie Mellon University. And she majored in chemistry. And her plan was to get her bachelor's degree, work as a chemist for a few years, and save up enough money to eventually go to med school. Arpita: 14:41 Is this still in the time where a chemist is a pharmacist? Where does this overlap with Aarati: 14:47 Oh, good question. I don't think so. I think we've moved on since then, since Wilbur Scoville. Is that? Yeah, we've moved Arpita: 14:55 So this chemist is the way we would think about a chemist now as someone who is potentially working with a lot of different compounds and Aarati: 15:02 Yes. Much more like what we have today, a traditional chemist. Arpita: 15:07 Got it. Aarati: 15:08 So Stephanie attended college from 1942 to 1946, which meant that once she graduated, she was entering the workforce right at the end of World War II. And this was an interesting time because since the war had just ended, many men were coming back from the war and reentering the workforce. But they weren't all back yet, so there were still job opportunities for women due to the scarcity of men. But- I'm kind of extrapolating here a little bit- I think that if a man and a woman applied for the same job at the same time, the man would probably be given preference. And so while Stephanie had job opportunities that she could apply for, she was in competition with the men who were coming home from war. So that made it a little harder. Yeah. So she had two options at this point. Um, one was to go into teaching. A lot of women who had been in science research were leaving to follow careers in teaching where I'm guessing there was less competition from men. Arpita: 16:08 Yeah, I also feel like that teaching skews female, usually. Especially Aarati: 16:13 Yeah, exactly. But Stephanie was, in her own words, stubborn, and she decided that if she was going to work, she wanted to do research. So she applied for a position as a chemist at the DuPont Company, which is a chemical company in Buffalo, New York. Arpita: 16:30 That still exists. Aarati: 16:32 It does. Um, she chose this company because she was excited by the research that she saw going on there. She thought it had a lot of potential. And also because it was one of the few companies that paid men and women the same starting wage. Arpita: 16:46 Whaaat? Aarati: 16:46 Yes. Equal opportunity. Arpita: 16:48 What year is this? 1930 something? Aarati: 16:50 1946 or 47, I believe. Arpita: 16:53 1946. Okay, wow. That feels like a huge advancement. That doesn't even happen now. Aarati: 16:59 I know, right? We're still talking about wage gap here, 100 years later. Arpita: 17:05 Yeah, literally a hundred years later. Um, wait, DuPont made Teflon? Aarati: 17:11 That makes sense. Arpita: 17:12 It makes sense. And also, I think Aarati: 17:14 In the context of this story, that will Arpita: 17:16 in the context of the story. Yeah, that's exactly what I was gonna say. Yeah, Aarati: 17:21 Um, yeah. I'm going to talk about some of their, um, Some of their inventions, but I didn't get to Teflon specifically, they, they're all over as you will soon learn. DuPont is just everywhere actually. So it, Arpita: 17:36 I honestly, truly believe Aarati: 17:38 Yeah, it was kind of very surprising to me to hear that or like to know that because I'd never heard of DuPont before I researched the story and I'm like, they made everything. They've, they've, I think they made Tupperware too. Um, I think that, I believe so. Arpita: 17:53 Oh, after World War II, a man named Earl Tupper received a block of polymer from the DuPont company, Aarati: 18:02 Ah, okay. There you go. Arpita: 18:05 And then he was, he was hoping plastics manufacturers would invent peacetime uses for this new material. And then he tinkered with molds for months, and then he created the Wonder Bowl, which then he patented. And then branded as Tupperware. Aarati: 18:24 Yeah, but it says given to him by his supervisor at DuPont. So, I guess he did work at Arpita: 18:30 Oh, he did work there. Ah, got it. Aarati: 18:31 Yeah. So, yeah, they're, they're everywhere. They're everywhere. Arpita: 18:36 Yeah. Aarati: 18:38 Okay, so. Yeah, Arpita: 18:40 Carry on. Aarati: 18:42 I was actually thinking about doing him Earl Tupper for this episode, but Arpita: 18:46 Really? Aarati: 18:47 well, when I was researching, I was like, okay, which polymer person can I do? And I was Arpita: 18:51 Yeah, yeah, yeah. That's kind of funny that his name is Tupper and that's why it became called Tupperware. I definitely did not know it was named after a person. Aarati: 19:02 Um, okay. So back to Stephanie. So, she interviewed at DuPont, and she was interviewed by Dr. William Hale Charch, who was a research director whose claim to fame was that he had invented a way to make cellophane waterproof. Arpita: 19:19 Cellophane? Like the crinkly plastic Aarati: 19:22 Mm hmm. Arpita: 19:24 Is it not waterproof? Aarati: 19:25 Well, he invented the way to make it waterproof, so I guess now it is. Arpita: 19:29 But isn't it just like a piece of plastic? Why would water seep through it? Unless I'm I don't know what cellophane is. Cellophane I thought was like what candy wrappers are, you know, like that crinkly Aarati: 19:37 Yeah. But I think that's waterproof now. So cellophane itself is made of cellulose. Arpita: 19:45 Oh. Aarati: 19:47 Yes, it says cellophane is highly permeable to water vapor but may be coated with nitrocellulose lacquer to prevent this. So maybe that's what it was? Arpita: 19:57 And then if it's a lacquer that's probably why it is sort of like that shiny crinkly Aarati: 20:01 I would assume Arpita: 20:02 Okay, Aarati: 20:03 Yeah, yeah. so. that's his claim to fame. Um, so he's interviewing Stephanie. When the interview was over, he told her that they would let her know decision within the next couple of weeks and here Stephanie decides to go out on a limb. She told Charch that she actually had another offer from another company, which I don't think was true, technically, and asked if he could let her know sooner, whether she got the job or not, because she had to give the other company an answer. Arpita: 20:34 I've done this too. Aarati: 20:35 Have you? Oh my god. That's amazing. Has it Arpita: 20:40 I mean, there's like no Yeah, it did work. And there was really no verification either. Like, how are they going to Aarati: 20:46 How are they gonna, yeah. Because even if they ask you like, Oh, what are the company? You can just be like, Oh, I prefer not to say. Like, or. Arpita: 20:53 They can't ask you that. So, I mean, you can always say, and it, it did work honestly, that I did the Aarati: 20:58 Amazing. Arpita: 21:00 I feel like we a lot in Aarati: 21:01 You do. Because it worked for her too. Charch was obviously very impressed with her and he literally called his secretary into the office on the spot to dictate an offer letter for her. Yeah. Arpita: 21:15 Okay, that didn't happen to me, but Aarati: 21:17 Okay, not quite that, but still, yeah. So years later, Stephanie said that she suspected that he liked her assertiveness and that's why she got the job. So there you go. So Stephanie starts working at DuPont and I'm going to take a minute here to tell you a little bit about what I did research about DuPont as a company because it is important to the story. So shortly before World War II, DuPont had introduced nylon, which was the world's first synthetic fiber. Nylon is unique for a couple of reasons. First, because it's a synthetic polymer, meaning that nobody had to grow it like cotton or gather it from animals like wool or silk. Instead, you made it from petroleum, which made it a lot cheaper and faster and easier to produce than natural fibers. Arpita: 22:08 Yeah. Aarati: 22:09 And secondly, nylon is thermoplastic, meaning that its properties change when you change the temperature. So at very high temperatures, it melts into a viscous fluid, and at colder temperatures, it solidifies. So because it's thermoplastic, that means that you can mold nylon fibers into a number of different shapes, depending on what you're making. Nylon is also lightweight, strong, flexible, absorbs moisture, and dries out quickly, which made it really great in hot and humid conditions. And so pretty soon nylon was being used to make everything from ladies stockings to ropes, um, toothbrush bristles, carpets, parachutes, dresses, backpacks, like it just had so many uses. Yeah, so many uses, and that made it a huge commercial success for DuPont. Like, they were making millions. Arpita: 23:03 Isn't the reason that we don't use nylon a ton today is because it's super flammable? Aarati: 23:08 Um, I think we still use it quite a bit, like for clothing especially, like nylon clothing, but I don't know if they're, Arpita: 23:15 Not, um, polyester? Aarati: 23:18 That too. That too. Yeah. Arpita: 23:22 I was gonna say, the reason I remember this is, I don't know if you remember, but it's probably when we were in elementary school... Aarati: 23:27 Mm hmm. Arpita: 23:28 But there was a huge thing about making kids pajamas, uh, flame retardant. And I guess for some reason, a lot of kid's pajamas, just because they were so cheap, especially pajamas, I think, were made with nylon and I think there were these issues with, especially at night, if there's, you know, an emergency, your clothes are not flame retardant, they're very flammable. And so I think bedding and especially pajamas, whereas there's like this big thing, I remember seeing all these labels on clothes to be like, this is not flammable, like not flammable fabric. And I wonder if that's when it was like somewhere around there was maybe when things became less nylon. Aarati: 24:11 Yeah, because I don't think I, Arpita: 24:13 verify that, Aarati: 24:14 I don't think I read about, like, I definitely don't think it's flame resistant at all, but I read more that it would melt at high temperatures versus catch on fire, which would still be a problem for, yeah, still bad for making clothing and, uh, kids pajamas and stuff in a fire. You definitely don't want clothes that melt. Arpita: 24:33 Yeah. Anyway, side note, Aarati: 24:36 At the time, nylon was being used for everything. It's this huge commercial success. And so this kicked off a race between DuPont and other companies like Monsanto to create more synthetic polymer fibers. And therefore, Stephanie is put into a laboratory where the team was trying to develop new types of synthetic fibers with different properties, like different strengths, flexibility, flame resistance, things like that. So all these different, um, characteristics. And she really loved it. She found it very challenging and fulfilling. And over the years, she was part of research teams that created a number of different synthetic fibers, including polyester, which you mentioned, and spandex. Arpita: 25:20 These are huge. These are... Aarati: 25:21 so many millions. Arpita: 25:23 So like crucial to all the different types of fabrics and materials we use today. And I can't believe all of these came out of one company. Aarati: 25:32 It's crazy. Arpita: 25:33 I don't think I realized how pervasive it was. Aarati: 25:35 And that Stephanie had a hand in all of them. It doesn't sound like it was like, you know, ten different research teams all working on Arpita: 25:41 Right, Aarati: 25:42 It's like this small group that's working on synthetic fibers that Stephanie was part of, so it's pretty remarkable. Arpita: 25:50 Yeah. Aarati: 25:51 About her time at DuPont, she said, quote,"I was very fortunate that I worked under men who were very much interested in making discoveries and inventions. They were very much interested in what they were doing, and they left me alone. And I was able to experiment on my own and I found this very stimulating. It appealed to the creative person in me." End quote. Arpita: 26:11 Love that. I like that part where she says, they left me alone. That's key. That's so key. Aarati: 26:17 I was like, Arpita: 26:18 I relate to that so much. Yeah. Aarati: 26:20 Same. I'm just like, why do you want a meeting? Just leave me alone. We don't need to talk. I'm doing my job. Leave me alone. Arpita: 26:27 That's so relatable. Aarati: 26:29 So she loved her job at DuPont. And in fact, she loved it so much that even though it was supposed to be just a temporary way for her to earn money so she could go to med school, she ended up staying at DuPont for her entire career. She stayed there for 40 years. Arpita: 26:43 Wow. I feel like that's not very common. Like that's her first job and then she just stays there her whole career. Aarati: 26:48 Not anymore. I feel like that's what the like, you know, the older generations are like, stay there, work your way up the company. And it's like, that just doesn't happen anymore. Arpita: 26:58 Right. Aarati: 26:59 Um, in 1950, her lab moved to Wilmington, Delaware. And in 1959, Stephanie won an award from the American Chemical Society for a paper she co authored with her supervisor, Paul W. Morgan, called the Nylon Rope Trick. This paper demonstrates a process called step growth polymerization, which is pretty much what it sounds like. Um, so like, as I mentioned, polymers are long chains of repeating units called monomers, and in step growth, polymerization to monomer units come together to form a dimer. A third one gets added on to form a trimer. A fourth one gets on to be a tetramer and so on until you have this really long polymer chain. Stephanie demonstrated that anyone can make a nylon polymer using this kind of step growth polymerization reaction. What you do is you take a beaker of a chemical called hexamethylene diamine, and then you gently pour another chemical called sebacoyl chloride in cyclohexane on top of it. So now you have two layers of liquid in the beaker, and at the interface where the two liquids meet, the hexamethylene diamine, and the sebacoyl chloride react to form nylon monomers. And then a bunch of those monomers will link up one by one to form a nylon polymer. Arpita: 28:27 Okay, and this is happening in the beaker. Aarati: 28:30 In the beaker. Yeah. And so then the reason it's called the nylon rope trick is because when you see it in real life, it looks like you're just reaching in and magically pulling out this long unending strand of nylon out of this beaker full of clear liquid. Arpita: 28:46 That's so cool. Aarati: 28:48 You can just keep on pulling it out and pulling it out and it keeps on, because it's step growth polymerization, the monomers just keep on getting formed and added to the end of the string, so it's really cool. Arpita: 29:00 Big is this string? Like is it super thin? Aarati: 29:05 Yeah, it's really thin, but it's big enough that you can, like, hold onto it and, like, pull it. Yeah. Arpita: 29:11 so It's actually like quite substantial. Aarati: 29:13 Can, like, wind it around your finger. Arpita: 29:15 That's crazy. So then it's the reaction is happening where the two liquids meet, assuming they're different enough densities that they stay separated. But then, as you pull the thread out, it's gonna continue reacting, I assume, until both liquids have run out. Aarati: 29:30 That... in theory, yeah. Arpita: 29:31 So cool. That's super cool. Aarati: 29:33 Fun side note was a lot of people call this the Spider Man web shooter experiment because one could imagine that Peter Parker has these two chemicals hidden in his suit and when he needs to, he just like mixes them and magically creates this instant nylon rope to swing on. So I thought that was pretty cool. Arpita: 29:51 Okay, high key, that is so cool. Like, even if you obviously aren't like swinging on it, like, what if you had a Spider Man suit that like, this reaction was happening inside, and you could just like, produce the thread? That is so sick. Like, what an amazing party trick. Aarati: 30:03 And Peter Parker was smart, like, canonically, he was, you know, a genius, so this is highly possible that he, he was, like, really good at chemistry and he figured this out. Arpita: 30:14 Wait, wasn't he, wasn't he like, in a radioactive, like, dumpster or something? Isn't that how he became Spiderman? Aarati: 30:20 He, He was bitten by a radioactive spider. Arpita: 30:23 Bitten by a radioactive spider. Okay, not the dumpster. Aarati: 30:26 I think he, like, went to a laboratory or something and, or, like, this radioactive spider escaped from a laboratory where they were testing radioactive spiders and he got bit by it. Yeah. Arpita: 30:37 Got bit by the spider. You're right. You're right. Aarati: 30:40 Um, okay. So, tangent, but back to the Arpita: 30:44 No, I love, I love those tangents. Aarati: 30:47 So, in the 1960s, economists started warning people of an imminent nationwide gasoline shortage. Yeah. So the higher ups at DuPont were like, Hey, if we can make a polymer fiber that is lightweight, hard as steel and holds up against extreme conditions, maybe we could replace the steel wires that run through car tires, which would make the wheels lighter and the car would have better fuel efficiency. So, less petroleum. Arpita: 31:15 I didn't realize they used to be steel wires. Aarati: 31:17 Yeah, I didn't either. Arpita: 31:19 That feels so cumbersome. Aarati: 31:21 It does feel, it does feel really heavy and slow. Arpita: 31:26 Totally Aarati: 31:27 So Stephanie was one of the researchers who took up this challenge and at the time she was working with these very long extended polymers called aramids or aromatic polymers because they were made up of these long chains of benzene rings. And a benzene ring, for anyone who needs a reminder, is made up of six carbons in the shape of a hexagon called an aromatic ring. So her polymer was made up of a bunch of these rings in a row. And she and her supervisor, Paul W. Morgan, calculated that because the benzene rings were so big and bulky, if they were able to form fibers out of them, the fibers would be very stiff and strong. But, um, there was a problem because to actually make a fiber out of any polymer, you first have to get the polymer into a liquid state and then put it into a machine called a spinneret, which, like its name sounds, spins around and extrudes, it extrudes the polymer out of tiny holes to form fiber strands. Arpita: 32:33 I liked that they called it a spinneret and not just like a spinner. Like a Aarati: 32:36 a spinneret, yes. It's dainty. Arpita: 32:41 So cute. Aarati: 32:42 So the question was, how do you get the polymer into liquid form? And one way we already talked about with nylon is heat it up and melt it. Um, but with the aramides that Stephanie was hoping to use, the long repeating chain of benzene rings also meant that these polymers would only start to melt at really high temperatures, like 400 degrees Celsius, which is 750 degrees Fahrenheit. So they figured it would probably be easier and more cost effective to try to dissolve the polymer into a solution. So that was Stephanie's first job, to find a solvent that would actually dissolve these types of polymers. But when she succeeded in getting these aramid polymers to dissolve, the liquid looked really weird. It was cloudy and fluid and kind of had the consistency of buttermilk. And when she, yeah, kind of like lumpy and weird. Yeah. And when she stirred it, she noted that it had this shimmery opalescent quality. Arpita: 33:49 I feel like nothing in a chem lab or a wet lab should be chunky liquid. You have done.... Like something has gone awry. If something looks chunky, that's disgusting. Aarati: 33:59 That's exactly what people thought. It was like, this is very different from the other polymer solutions that the scientists at DuPont were familiar with. Most of the other polymer solutions were clear and viscous. And usually, like you said, if a researcher saw something like what Stephanie was seeing, they would thrown it away thinking it was contaminated or something had gone wrong. But Stephanie had this intuition about it. She's like playing with it and she's like, I think this will work. And so she took it to the guy who's in charge of running the spinneret and was like, Hey, can we put this in the machine and try spinning it into fibers? And he was like, no, absolutely not. Like, Yeah, yeah, like, no, Arpita: 34:44 Get that shit away from me. Like, Aarati: 34:47 He's like, it's got some weird, like, Arpita: 34:50 Pearlescent milk away from me. Yeah. Aarati: 34:54 He's like, it's going to clog up the holes in the machine. It's going to cause a big mess. I'm not doing it. Um, yeah. But Stephanie, remember is stubborn. She was very persistent and she kept asking him and asking him and asking him for days until finally he was just like, okay, fine, geez, you know, let's just do it. So they put it in the spinneret and to both of their surprise, this weird polymer solution had absolutely no problem creating fibers. It didn't clog up the machine or anything. It was beautiful. And these fibers were also very different from anything that had been created before. They were extremely hard and stiff. Stephanie said, quote,"The first sign that we really had that something unusual occurred as I stood by the spinning equipment and tried to break some of the newly spun fibers. Unlike ordinary nylon, this fiber was very difficult to break by hand. At that moment, I knew we had a most unusual fiber." End quote. Arpita: 35:53 So interesting. I'm imagining them coming out super stiff, like dry spaghetti. Aarati: 35:56 Yeah, I don't know. I haven't actually seen a video of this. I've seen a video of nylon coming out of a spinning machine, which is pretty cool, but I haven't seen like aramid polymers. Arpita: 36:07 Just based on the description of it being difficult, like it being stiff and then it being difficult to tear. I'm imagining Uncooked spaghetti coming out of it. Aarati: 36:16 So it turned out that the weird solution that Stephanie had created is is called a liquid crystalline solution, and it has the ability to flow like a liquid so it didn't clog up the spinneret, but also all the molecules are oriented in the same direction, just like in a crystal. So when you look at a crystal's atomic structure, it is very organized. All the atoms are forming this very neat arrangement, and that's what makes it very strong. And it was the same with this fiber. Once it was extruded, all the molecules in the fiber line up in this very organized way, and that's what made the fiber very strong and durable. Obviously, this was a pretty incredible breakthrough. Stephanie did a bunch of testing to confirm that what she had made was real and repeatable before taking it to the higher ups at DuPont. And they were immediately like, wow, this stuff has potential. And they assigned a whole group to work on developing different products out of it. But this is what I found interesting. Stephanie herself had no idea what these fibers could be used for. She wasn't really part of the development process at all. She was just experimenting and trying to make fibers with different properties. So she didn't know, like, what they would be turned into. Arpita: 37:34 What they'd be used for. That's so interesting. Like she was so far upstream that she was just interested in having certain qualities or certain combinations of qualities, but didn't really think about... That's, that's so interesting because when I think of drug development, it's almost the opposite. It's like you have a specific use and then you're trying to think of how to generate or engineer a molecule or whatever your mechanism is to then have that effect. So it's interesting that she was just creating things and then being like, well, I don't know what it's going to be used for. Aarati: 38:05 Yeah. It's like, we have a disease that we're trying to create a cure for, and you always know that. You always know what the end game is, Arpita: 38:11 You have the end point. Aarati: 38:12 But yeah, she was just like, oh, I'm just, you know, Throwing things around, experimenting with something. Hey, look, I found this cool thing. I don't know. You could use it for something maybe, you know. Um, that's not my Arpita: 38:24 It's like a very different approach. Totally. Aarati: 38:27 So her discovery of aramid polymers gave rise to a bunch of very unique types of fibers. In 1967, DuPont released an aramid fiber called Nomex, which is flame resistant. Um, it can withstand temperatures up to 370 degrees Celsius or 700 degrees Fahrenheit. Yeah, so really hot. Kids pajamas made of Nomex. That's what we need. Yeah, Arpita: 38:56 Definitely what kids need. Aarati: 38:57 That's what we need. Um, but it is a common material used in firefighting equipment, aircraft, circuit boards, and transformer cores to prevent fires. Another type of fiber, marketed under the name Kapton, forms a film that is stable across a wide range of temperatures from-270 to over 400 degrees Celsius. Yeah, Arpita: 39:19 That's a huge range. Aarati: 39:23 Yeah. It also works in high vacuum environments. And so because of this, it's used in flexible printed circuits, space blankets, and satellites. Arpita: 39:33 I don't think I really thought about all the different materials that exist in this world. I'm not going to lie until just now, Aarati: 39:39 Space blankets! Did you know we need space blankets? In 1971, they released Stephanie's most famous aramid polymer, Kevlar. And, again, like we said, when Stephanie created Kevlar, she wasn't thinking, like, Oh, I want to create a fabric that can withstand bullets. She was just focused on pushing the boundaries of what types of fibers she could make, and was inventing new fabrics. And when she tested the new Kevlar fibers, Stephanie found that they were five times stronger than steel and fire resistant while still being very lightweight. Arpita: 40:16 Wow, what? That's such a crazy intersection of qualities too. And it's like, you think of steel as basically being impermeable. I mean, obviously that's not true, but you think about it in your head. And then also just so dense and heavy. Wow. Amazing. Aarati: 40:30 Um, so she created this material, this fiber, and then it was actually another researcher at DuPont named Joseph Rivers, who had been looking for fibers that he could use to make bulletproof vests. And he saw the potential for Kevlar to be used this way. When he heard about this new fiber that Stephanie had created, he asked if she could possibly spare just a tiny bit for him to test. And as we know, the rest is history. So yeah, Arpita: 40:58 It also is kind of interesting that these two departments are working, sorry, this is back to my original point. Like they're just working so apart from each other. So there's this like whole section of DuPont that's like, how do we solve XYZ problems? And then there's this other group of people who are just like, We made this today. Aarati: 41:15 yeah, there's like the experimental team and then there's like the development team and it's like the experimental team is just like, We created a fireproof thing. Okay. Now it's waterproof. Okay. We create another one that's like super strong and I don't know what to do with it, but here you go. And then the development team is like supposed to find uses for all this stuff. Arpita: 41:36 Yeah. I'm like, I'm imagining the experimental team, almost spinning like a wheel of fortune style wheel being like, what's it going to be today? Like today. Yeah. You're just like, what's it going to be today? It's going to be like flame retardant today. It's going to be super strong. Today's going to be super light. And then. Yeah, it's just so interesting because I'm really comparing it to drug development, which is really the opposite. So, it's very interesting that this is the way that, you know, pipeline goes. Aarati: 42:01 Yeah. Especially that, because I think part of it in biology, like we don't have. The money or the time to just kind of like, you know, be like, okay, we, we just created this thing that we have no use for right now, you know, like, Arpita: 42:15 Yeah, that would not get funded. So, I don't Aarati: 42:18 Exactly. Arpita: 42:20 Yeah, I wonder if it is just less cost prohibitive. So, if you're doing biological research that, you know, involves animals or You know, like all these, like all these pieces that are maybe more expensive. I don't know if this is true, but maybe it's less cost prohibitive to do some of these chemical experiments. Like maybe it doesn't matter because all these raw ingredients are less expensive. I Aarati: 42:45 Yeah. I could totally see that. I'm, I'm not sure, but I can definitely see that. It's like, oh, you ran out of this? Just make more. It's Arpita: 42:53 Right. Exactly. Aarati: 42:54 Yeah. And petroleum was super cheap back then, Arpita: 42:57 That's True. That's a good point. Aarati: 42:59 That's a big reason they were doing all of this. So, by 1975, Kevlar vests were being made available to police departments. DuPont partnered with the International Association of Chiefs of Police, or IACP, To promote the use of body armor by creating the IACP/DuPont Kevlar Survivors Club. Since it started in 1987, they have honored over 3, 100 officers whose lives were saved or escaped a serious life altering injury because they were wearing a Kevlar vest. Arpita: 43:35 Wow. Aarati: 43:36 Yeah, and that's just law enforcement. It does not take into account the thousands of military personnel it's probably saved... Arpita: 43:43 Mm hmm. Aarati: 43:44 ...over the years as well. Arpita: 43:45 Mm hmm. Aarati: 43:46 There are now over 200 end use applications for Kevlar, including being used to line military helmets, in paraglider suspension ropes, to sheathe fiber optic cables, as a structural component in cars, cell phone cases, and to reinforce concrete. Arpita: 44:05 Wait, cell phone cases? That feels like the out one, thing Aarati: 44:09 Like the Otter box. Arpita: 44:11 Yeah, seriously. Aarati: 44:12 I needed one of those last episode. Arpita: 44:15 You did. I'm, your list, like, made so much sense. I'm like, oh yeah, super intense. Like, yeah, that for sure needs to be reinforced. It's like, your cell phone. Aarati: 44:24 Yeah, your cell phone. Yeah. But I mean, given how much we depend on it and everything, you know, I actually had a dream last night that my cell phone shattered again. I was like, freaking out. Arpita: 44:36 It's haunting your nightmares. Aarati: 44:37 It really is. Arpita: 44:40 You're never going to go ride a roller coaster ever Aarati: 44:43 I Arpita: 44:43 again. Just like, for real. Aarati: 44:44 Or maybe I will if I have a Kevlar cell phone Arpita: 44:47 A Kevlar case. That is so funny. Aarati: 44:51 Yeah, but it's these Kevlar fibers used everywhere. And Stephanie said, quote,"I guess that's just the life of an inventor. What people do with your ideas takes you totally by surprise." Arpita: 45:04 Does she get, um, I guess not royalties, but I assume that the intellectual property belongs to DuPont. So she just doesn't get anything out of this. Aarati: 45:13 Well, she actually signed over all of her royalties to DuPont. So she was given the patents and I'm not sure why she did this, but like, she was not in it for the money at all. She just gave them the royalties and they generated billions. Billions of dollars from her work and it's not just Kevlar also remember she was like on spandex too and nomex and polyester and like all these different things so she just didn't seem interested Arpita: 45:42 get don't That's... Aarati: 45:43 I don't either. Arpita: 45:44 Well, largely because they're a corporation, you know, like I could understand like, Oh, I don't want the royalties. They're going to go somewhere else, but why would you give it to a corporation? That feels crazy. And how did patents work? If you were awarded the patent and it was in your name, then how do you, is it anytime someone uses your patent to create something? Do you get some small percentage of that? Is that how patents work? Aarati: 46:08 I think so I'm not a hundred percent sure because I would assume that even if she did have the patent in her name DuPont would have gotten something because was creating it with their lab equipment and you know in their facilities So that's what I would have assumed but I... so I would have guessed that they would have gotten something out of it anyway, even if she didn't sign over all the royalties, but she just did. And I guess part of it is because she didn't marry or have any children. Her, like, work was her life. just very focused on her research. And so, and she loved her job, like I said, so just gave it all back to them because she loved it so much, which I can't comprehend, really. Arpita: 46:53 I don't relate to that one bit, but good her. I guess maybe also like if she didn't have like a clear person to leave it to, then there was maybe less of an incentive to keep the money in some way. Well, okay. Aarati: 47:06 Yeah. So she retired from DuPont in 1986 and spent the rest of her life tutoring high school kids in chemistry and encouraging young women to become scientists. In 1995, she was the fourth woman to be inducted into the National Inventors Hall of Fame. fame. DuPont also awarded her the Lavoisier medal, hope I'm saying that right, for outstanding technical achievement as a quote, persistent experimentalist and role model whose discovery of liquid crystalline polyamides led to Kevlar aramid fibers. Arpita: 47:44 Wow. Aarati: 47:45 End quote. Yeah. Arpita: 47:47 Do we have someone else who was also in the International Inventors Hall of Fame? Was it Hedy Lamar? Aarati: 47:52 Oh, it might have been. Arpita: 47:54 Yeah, I think it might have been. I thought we had someone else who was in the Hall of Fame. Anyway. Aarati: 47:59 Yeah. When would Hedy Lamarr have been in there? Because she was only, like, Stephanie Kwolek was only the fourth woman, so, Hedy Lamarr, if she was in there, would have had to be number one, two, or three, I would guess. Arpita: 48:14 Yes, she was, uh, inducted in 2014. Aarati: 48:18 Oh, she was inducted much later. Okay. Arpita: 48:20 She was inducted posthumously, I think. Aarati: 48:23 So Stephanie Kwolek was inducted when she was still alive. Um, in 1996 Stephanie was awarded the National Medal of Technology for her work on synthetic fibers. And this is a medal that was awarded by the U. S. president. So there's this kind of. hilarious video clip where she's getting the medal from President Bill Clinton. Um, and he's like this ginormous 6'2 man and she's this tiny 4'11 woman. And so like the discrepancy between her heights is just amazing. Arpita: 48:55 That's so funny. She's teeny tiny. Aarati: 48:58 She's tiny. I'll put a picture of it on the website so you can see because it's, really funny. Arpita: 49:02 That's so Aarati: 49:03 funny. In 1997, she received the Perkin medal from the American Chemical Society, and in 2003, she was inducted into the National Women's Hall of Fame. And there are a bunch of other honors and awards, but literally we'd be here all day. So I'm gonna leave it at that. Arpita: 49:23 So many accolades. Aarati: 49:24 Yes. She died on June 18th, 2014, at the age of 90 over her lifetime, she was granted 17 patents. Um. But as I, as we said before, she signed over all the royalties, so never saw money from it. So I wanted to end on a quote from a biography that was written about her by Edwin Brit Wyckoff. And he wrote that"Young Stephanie wanted to save lives as a doctor. Instead, she grew up and learned to save lives as a chemist." And I thought that was, really nice. Arpita: 50:03 That is really nice. I think it's interesting too, because I think a lot of young people and like kids think about wanting to do good in the world. And it does feel like being a doctor is like the very clear path to do that. But there are, I feel like even just as this podcast, we've just seen so many different ways to, you know, change the way we think about the world in ways that are not just straight medicine, you know? Aarati: 50:25 Yeah. It's, it's really incredible to think about how the world is so different now. Like, I was just thinking when you said, um, you hadn't thought about how many different materials... Arpita: 50:36 Yeah. Aarati: 50:37 ...existed until just now. And I was like, so that means that, like, before they invented Nomex, these firefighters were just rushing into fires with, like, normal clothes on. Isn't that crazy? Arpita: 50:49 And I don't think about, like, all the smaller things, like, you were talking about, like, what they were used in switchboards, or used to encase fires, and it totally makes sense, right? You have these, like, huge servers, and, like, all these machinery, and you, like, even things that you don't interact with or touch on a daily basis, like, all those components need to withstand certain stressors. Aarati: 51:07 Yeah. And Arpita: 51:08 did not think about Aarati: 51:09 one tiny little spark and it sets the whole thing aflame, like our whole world comes down, like the internet breaks because... Arpita: 51:16 Yeah, Aarati: 51:16 You know? Arpita: 51:17 Exactly. Aarati: 51:18 So yeah. So it's, it's pretty incredible. Yeah. Yeah. Arpita: 51:21 That's so interesting. Aarati: 51:23 That's the story of Stephanie Kwolek. I hope that my brother is happy and will get off my case a little bit. Arpita: 51:30 This was good. I feel like this was very approachable. I totally, yeah, it's not too technical. I got really nervous when you started and you said, you're going to talk about polymers, I was going to be like, Oh God, really got to turn my brain on for this on my day off. Aarati: 51:42 No. Arpita: 51:43 It was great. Aarati: 51:44 Well, that's why I was resisting him so much too. I was like, polymers! Talk about polymers. But Arpita: 51:51 There's like, you and I are like biologists. Every time we have to do something, that's not biology. We're just like, oh shit. Like, what are we going to do? Aarati: 51:56 Yeah, exactly. Exactly. Yeah. Arpita: 52:00 like math at one time. We're both just like, huh, Aarati: 52:03 God. I'm, I'm still like traumatized from that episode. Arpita: 52:08 Yeah. I don't know if we're going to go run it back for another mathematician, but Aarati: 52:12 Yeah. Well, I don't know. It's up to our audience. If you want us to do another mathematician, write in and tell us and we will have to do it. So, Arpita: 52:19 We'll try. Aarati: 52:20 Up to you guys. Arpita: 52:23 Great story. I loved it. Aarati: 52:25 Thank you. Arpita: 52:26 Thanks for listening. 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