Interview with Dr. Frank Leibfarth from the University of North Carolina at Chapel Hill about his group's exciting work in polymer chemistry as well as topics related to his collegiate football career and the challenges of managing an academic lab in the era of COVID-19.
Polymer chemistry has been one of the main disruptive forces in the last few decades, having a profound impact on materials used in all applications, enabling new technologies and profoundly impacting everyone’s life. Polymers are at the core of modern material science and despite having generated some concerning environmental challenges, it’s hard to imagine a future without them.
Dr. Leibfarth is one of the most creative minds in polymer chemistry today and he is leading some incredible innovation in the way these materials are made and applied. He shares a fascinating story of elite collegiate American football, science, inspiration and creativity, as well as where different disciplines converge and provide the disruptive force to change paradigms.
Paolo and Frank discuss stereo-controlled polymerization, novel functionalization, exploration of structure-function relationships, as well as Frank's personal and professional growth.
Frank Leibfarth 0:06
It's a really complex socio economic chemical problem, the problem of plastic waste. But we need to solve all these problems right because their plastic currently is polluting our oceans, it's filling up our landfills right in the status quo is not a sustainable way to move forward.
Paolo Braiuca 0:27
That status quo is what Dr. Frank Liebfarth is trying to change with his work on the chemistry of plastics as an assistant professor of chemistry at University of North Carolina at Chapel Hill. And it's what landed him on the Chemical & Engineering News' 2019 Talented 12 at least two brilliant young scientists taking on some of the world's toughest problems with clever chemistry. In Episode Two of the Science With a Twist series "Bringing Chemistry to Life", we speak with another member of the Talented 12 about their work and trends in their field. I'm your host, Paolo Braiuca, Senior Manager of Global Market Development at Thermo Fisher Scientific. We began by asking Dr. Leibfarth not about this postdoc with influential chemists Tim Jamison at MIT, or this Camille Dreyfus Teacher Scholar Award, but about a different accomplishment from earlier in his career. As a junior place kicker on the University of South Dakota American football team, he secured not one, but three USD kicking records.
Frank Leibfarth 1:29
A few years ago, somebody passed me. So I'm now the second all time leading score. But it hurt a little bit when somebody passed me. But the thing I was happy about it was another kicker, and I was a kicker. So we all stick together. So in the end, I'm happy for him. And records are made to be broken, but know that playing football was a fun, ephemeral, and now in my position, kind of it feels like another life ago.
Paolo Braiuca 1:54
So I guess being a kikah gives you an edge in terms of being an old leading all time leading scorer.
Frank Leibfarth 2:00
Sure, yeah. Every time the team scores a touchdown, I get to go and get a point. Right. One of the things is I played a number of years, I ended up playing three years there, so and we had a really good offense. So I benefited from that. And it was kind of the accumulation of points over time that got me there.
Paolo Braiuca 2:17
So I'm glad you were a kicker, because that's the only position of American football that Europeans understand. How does a record-scoring kicker become a high profile scientist?
Frank Leibfarth 2:26
That's a good question. I often ask myself that. I grew up playing athletics, you know, if you would have asked me what I was going to be, when I grew up, when I was a kid, I think the last thing I would have said was scientist, I grew up in a small town in an area that was dominated by agriculture. I didn't know any PhD scientists growing up, I really didn't really meet them until I went to college. But I always knew I like to make things my dad kind of had a side job as a carpenter. He drove a semi truck otherwise, and I love going and making things with him. But I also love the intellectual aspect of school and education. I even though I didn't know what I was trying to figure out a way to combine those things. And it was after my sophomore year in college, I really wanted to travel, but I didn't have much money. And I couldn't spend a whole semester abroad because I played football. So I was kind of in this pickle. And I asked my organic chemistry professor, hey, is there a way I could travel somewhere, but still get paid for it. And you know, do chemistry because I liked your class. And he pointed me to these National Science Foundation ru programs. And I think I applied for 10 of them and got rejected by nine of them. But the one I got in was at Columbia University. I say I went from a town of 10,000 people to a town of 10 million people, was overwhelmed by everything, the science, the city, but really found my passion in the lab. I love the intellectual atmosphere, I got to make things because I was doing synthetic chemistry. So it kind of combined all the things I liked. From then on out, I was committed to the career.
Paolo Braiuca 3:53
Okay, let's jump to the most recent years, right? And let's try to to try and position you somewhere in the chemical science. So am I correct? If I define you as a polymer chemist,
Frank Leibfarth 4:05
I'd say I self identify as a polymer chemist,
Paolo Braiuca 4:08
would you, would you recognize yourself as an organic chemist in any way?
Frank Leibfarth 4:14
Sometimes I get,
I don't know labeled as being an organic chemist, definitely a synthetic chemist. We do in my group, a lot of organic chemistry, I would say in synthetic chemistry. But really the innovations we're seeking to make are in polymer science and in polymer chemistry. So that's, that's why I think I clearly fit in as a polymer chemist. But that's one of the great things about polymer chemistry. And polymer science in general is it's inherently interdisciplinary. It sits kind of at the interface of all these different disciplines and you get to put on different hats depending on you know who you're talking to, or what day it is.
Paolo Braiuca 4:45
It can you tell us a bit more about the lines of research that you're currently pursuing in your in your team.
Frank Leibfarth 4:51
So I'd like to say our lab is not so much problem driven, but it's really driven by the chemistry and the chemistry we find interesting, and we want to Soon. So the application space we're pursuing is actually pretty vast. But it really distills down into a few fundamental chemical innovations we're seeking to make. And the three of those broadly, that I would say we're focused on. The first one is stereo selective polymerization. So that's trying to use the tools of asymmetric analysis to control the stereochemistry, during polymerization. And then ideally, right identify valuable material properties from those new materials we make. The second is in polymer, ch functionalisation. This is taking the polymers that we make on millions of tons scale that you know, most people and truthfully, myself when I was going through my education kind of found boring. And actually trying to make them interesting through really powerful but selective ch functionalisation techniques where we can take these really strong bonds and the polymers, modify them. And ideally, our focus right now is using those to upcycle, these really high volume polymers, and in the end upcycle them to the point where they can be reused over and over, so actually improve their recycling at the same time. And the third area is really on the interface with chemical engineering and polymer chemistry. And that is using continuous flow technology to automate polymer synthesis. Plug that into making large libraries of materials using things like artificial intelligence to help guide our synthesis, and discovering material properties that seemed counterintuitive, by being able to really probe large structure spaces.
Paolo Braiuca 6:30
So from your work on the stereo control polymerization, that was what won you the consideration for the Talented 12 if I'm not wrong, and I was reading your extremely interesting paper you published on Science, congratulation for that, by the way, polymer isotacticity is not really a new concepts. So what is, what is the real innovation of your work there?
Frank Leibfarth 6:52
Yeah, it's not a new concept at all. Giulio Natta won the Nobel Prize in, I believe, 1963 for discovering or defining what an isotactic polymer is and discovering isotactic polypropylene isotactic. polypropylene is made at over 60 million metric tons. It is the largest application of statistical analysis in the world. But since the time of nada, and he he had this he found the same problem, the mechanism through which you make stereo controlled alpha olefin polymers is this coordination insertion mechanism. And the problem since then is these are usually used using early transition metal catalysts. And if you add any Lewis basic component into that polymerization mixture, it will shut down catalysis or inhibitors
Paolo Braiuca 7:33
'cause it binds strongly to the metal, I suppose,
Frank Leibfarth 7:36
exactly. So, I guess that's the story of kind of how I came up with this project really started from just a fundamental interest. Ben Liszt came and gave a talk at MIT when I was a postdoc there and talked about these really beautiful catalysts he was making that were chiral counterions, I just was really inspired by that talk, and thought, Hmm, I wonder if I can do the same thing with polymers. So it started kind of from that pretty naive place. And I had, I did not have any experience in asymmetric analysis. In my training, I built the idea from there to identify a polymer class that was of interest that really hadn't, sterile control polymerization of that hadn't been solved yet, identified some properties that I thought would be really interesting, if we were able to control the stereochemistry of those polymers, nature's ability to control the structure of bio polymers, everything from their sequence, to their stereochemistry to their length is exquisite. There's a long history of polymer chemists being inspired by that, and moving towards that. And I think stereochemistry is one of the areas that has been underdeveloped in polymer science, we're pretty good at controlling the length of polymers, we're getting better at controlling the sequence. But the stereochemistry, especially of polar polymers, that have these loose basic sites, is really a big challenge. And I think area of the field that is really open for innovation in the near future.
Paolo Braiuca 8:58
So you've got the inspiration for these ionic polymerization from the work in a different field of chemistry.
Frank Leibfarth 9:06
Yeah, absolutely. I've been talking to my students a lot about this, like, there's a question in science, right? How do you teach creativity? How do you teach somebody to be creative? It's kind of one of the large existential questions that I don't think anybody has a great answer for. But I've identified how I'm creative, is I have a deep knowledge in polymer chemistry, right? That is my core discipline. But I try to learn as much as I can about fields that are kind of tangential to polymer chemistry, and really look for the places where those fields intersect. And then obviously, with with my core expertise in polymer chemistry, I think it's important then, once right, we are able to make an innovation, we can actually go and characterize those materials and see what they're good for. So that started selective polymerization paper, we didn't just do a stereo selective polymerization. We then actually made films of those materials we pulled on them until they broke and saw how strong they are. We saw how adhesive they were. Right, so we can take those fundamental chemical innovations and relate them to properties engineers really care about.
Paolo Braiuca 10:07
Am I understanding correctly, Frank, your using ionic polymerization in this application will open new opportunity to look at sort of different types of monomers for for your polymers, things that are slightly different than the traditional oil feedstock.
Frank Leibfarth 10:25
Yes, very good observation. One of our real goals as we develop as catalyst is to use feedstocks that are derived from bio renewable resources, right things that we can derive from lignin or sugar, or other natural resources like that. What nature loves to do is oxidize things, right? And that really doesn't fit with kind of the classical coordination insertion polymerization that makes petroleum derived polymers in some ways. coordination and search and polymerization are kind of the bedrock technology for polymer science in the last 70 years, is perfectly suited for petroleum derived products. But we really need to think rethink that catalysis if we want to start making plastics, from renewable resources, so we need to create polymerization techniques that are amenable to the oxidation processes that nature loves to do. Usually, you have highly functional products that come from nature, can we develop selective polymerization processes to use those products? So yeah, you're you're spot on in that observation.
Paolo Braiuca 11:26
So the future is going to be potentially from relatively simple small hydrophobic compounds, to fairly complex, multi functional ones. As monomers, they could potentially lead to completely different final products with completely different properties?
Frank Leibfarth 11:43
I mean, the scale these things are made, are made that is tremendous, almost unimaginable. If you're just sitting there trying to picture how much synthetic plastics are made per day, right, it would probably fill the building you're in, if you're in like a large building, I mean, these things are made, they're shipped by the railcar, more than a million tons of plastic is made per day. And that's, that's a lot of plastic, right. Because of that, it's going to be a combination of everything, I think there will be a large role to play for completely new materials from bio renewable building blocks, ethylene and propylene is actually a byproduct of petroleum refining. So in some ways, that's a waste product that we kind of have to get rid of. And the best way to get rid of it is to solidify it. And of course, then we can use that solidified product, right or something. So I think the important thing to do is right, most of the polyethylene and polypropylene, those petroleum derived polymers we use are single use. And I think that's we have to start moving away from can we also develop new chemistry to extend our use beyond single use, right, and ideally, that we can start reusing them?
Paolo Braiuca 12:43
So do you foresee a world where plastics will be chemically completely different materials?
Frank Leibfarth 12:49
I think some plastics will be completely different materials, and some will be modified from what they are now. And then there are some applications that are really high value is really, really important. I can think of things like sanitizing medical equipment, right? That we want to ship around the world to places maybe that can't effectively clean medical equipment. And when you open that syringe to give somebody a vaccine, you need to know there's no bacteria in there, it's completely clean, it's probably worth using the best polymer for that job, even if it may be single use, but your milk jug that you get from the grocery store, if that's a completely different material that can be recycled better, you know, that's probably good, or the plastic bag you get from the grocery store, right? So it's a really complex socio economic chemical problem, the problem of plastic waste, but we need to solve all these problems, right? Because their plastic currently is polluting our oceans, it's filling up our landfills, right. And the status quo is not a sustainable way to move forward. You know, money tends to talk, right? So if you can create something that is more valuable than the original material, I think that will catalyze a larger incentive for actually recycling materials, right.
Paolo Braiuca 14:08
And it's very clear how your work in this direction is supporting real real life application and particularly for remediation and environmental pollution and waste treatment as does that's very clear. And I want to take a segue from you're saying that some of the plastic we just need to be functionalized in a different way. So speaking about the ch functionalisation. Can you tell us a bit more on how you you go along the kind of work.
Frank Leibfarth 14:36
That work was originally inspired by some work I did in graduate school. I published a paper in graduate school. That allowed me to crosslink polyethylene. Well, there's two main applications for crosslinked polyethylene, the first of which is actually the piping that is starting to replace copper that goes from your hot water heater around your house, because it's nice and thermally stable, usually called pecs, tubing. Another bad guy. application is in replacement joints. A lot of replacement hips, the cup is made from ultra high molecular weight, cross linked polyethylene. But right now those are all cross linked and kind of a really messy radical process, usually using gamma radiation, so really high energy. in graduate school we I was able to collaborate with geepas on and my advisor Craig Hawker at us at UCSB, University of California, Santa Barbara. And we were able to take a bottom up approach to crosslinking, polyethylene where we're able to add in these unique monomers that that underwent a secondary reaction that created a more thermally stable Polymer. But then, when I got into my current position, you know, that project that I had done eight years earlier, kind of came back to be really valuable because I was in a oral exam of one of my colleagues, students, and she had just this really powerful reagent that could functionalize ch bonds, aliphatic ch bonds really selectively. And she was using them to do late stage functionalisation of pharmaceutical compounds. And I told her during that meeting, and then you know, my colleague, her advisor, that that could really work on polymers. And there's this problem in polymer chemistry, every time we try to crosslink, these branch polyolefins, right, you have to use these really harsh conditions, and you end up getting a bunch of side reactions. And it's just pretty messy. So we started working together, we developed a method that was really selective for polyolefins. It's a radical functionalisation process. And we show that we could do that to isotactic polypropylene within a reactive extruder. So our active extruder is essentially kind of a big oven that pushes polymer through with a screw. So you can really mix through sheer high viscosity materials. Also, that selectivity had not been seen in metal free type functionalisation. And we now are thinking of ways to use that to compatible eyes, polymer blends that are otherwise really difficult to separate and recycling streams. So when recycling streams, polyethylene and polypropylene, for instance, they have similar densities. And if you just melt them down and blend them there have really poor material properties. We're thinking, you know, can we develop a method where if you just take that bland sprinkling a little bit of reagent, can you now get out more interesting thermoplastic properties and actually be able to use that material mixture?
Paolo Braiuca 17:17
So reading your Chemical Science 2019 article? Seems like you're using photocatalysis, as well as that's quite interesting. It seems to be a hot topic at the moment in, maybe not in polymerization science, but in other fields of chemistry, am I right?
Frank Leibfarth 17:32
Yeah. photocatalysis is really unlocking interest in chemical transformations that a lot of people thought were impossible for a long time, or it could be done with other means that were far more complicated. Actually, after conceiving this first project that I talked about on the ch functionalisation of polyolefins, my group started thinking more broadly like, well, could we see functionalize other polymers? And how would that be useful? And we identify this photocatalytic method that was originally recorded by Corey Stephenson, he's at University of Michigan. And so we started testing that we found out that we could add these foreign aid units to polystyrene really efficiently. And you could use commercial polystyrene to actually even show that you could use post consumer waste to polystyrene. So if you just take like an old styrofoam cooler, chip off a little bit that was just as effective in the reaction as a pure feedstock. And that was good. And we had for a while a collaboration with industry who was interested in some of those materials. Another interesting route to possibly upcycle polymers make them more valuable than the initial material to create that economic incentive to reuse. Otherwise, single use plastics.
Paolo Braiuca 18:37
polymer science has been around for for for a lot of time, or several decades now. And and yet, the innovation that you're bringing into the field seem to be coming from your ability to get ideas from other parts of chemistry, or maybe from collaborations with other scientific disciplines. It's really inspiring.
Frank Leibfarth 18:59
I often tell my students, this term is used kind of in business a lot to be T people, like capital T. So what a T person is, is the downstroke of the T is your deep expertise in one discipline. In our case, that's polymer chemistry, right? I'm, I'm a polymer chemist, the students that come into my lab will be trained to polymer chemists. I want them to be really knowledgeable in that. But the horizontal aspect of that large T is your knowledge and all these other disciplines. I would never call myself a biochemist. But I love to go to my biochemistry colleagues seminars and try to learn something and try to pick up little tidbits right, that I could bring back to my own discipline. And if you can have an expertise in that, but a curiosity about other fields and where they can make a difference. I think that's a nice pathway towards being creative and making impactful contributions.
Paolo Braiuca 19:57
That makes me very curious. You mentioned the use of cntinuous flow to generate these libraries of polymers. And that's an interesting concept when you think continuous flow and polymers been solid materials, how does that really work?
Frank Leibfarth 20:12
Many plastics are solid at room temperature. But if you heat them up enough, often they flow and you can shape them into different parts, right. So that's what we usually call thermoplastics. Actually, most polymerization processes are done in some kind of continuous fashion. polyethylene, for instance, ethylene itself is a gas. So often, right, this is a gas continuously flowing over catalyst that creates that solid Polymer. And there are numerous different ways that have been engineered to isolate that continuous flow technology in a way, and polymer science isn't new. But I think there is a place to do this kind of what I would call intermediate scale, continuous flow technology, where you have really discrete control of all the different variables that could go into making a complex product. And if you can do that, and if you can automate it, you can start to make large libraries of materials pretty easily. And there are, I think, a lot of challenges in polymer science that we haven't started to tackle yet, just because they're so complex, when you start adding lots of different ingredients to a polymer, kind of like when you started adding lots of different ingredients, when you're cooking, you never know what's going to come out, right? You might taste it, it might be fabulous, if you buy taste you buy might be like, Whoa, I never want to do that again. So when you start making these large libraries, right, you get into the structure space, and you have all these variables that are interdependent. So you, oftentimes you can't predict a priori what's going to be the best material. So if we have an easy way, a user friendly way to make these large libraries, maybe we can start to discover, right, those materials that can solve really challenging problems in kind of as haystack it's kind of the needle in the haystack approach.
Paolo Braiuca 21:48
So is the long term goal of having a sort of toolset or toolbox to be able to explore systematically, their the accessible chemical space for any given combination of monomers and trying to get to all the possible different combinations and see the correlations with their functions?
Frank Leibfarth 22:08
Yeah, absolutely. And we Yeah, we really do see this, you know, once we're able to build it, we see it as a platform. Where right we would have the tools to make all these things. It's kind of like an automated peptide synthesizer, right? Maybe someday, we'll even get to the point where right other other labs could buy, right this tool, and then use it to solve the problems they want to solve. So if we can start to make these systematically, as you said, if we can make it so you know, a non synthetic chemist can operate something like this. I recently won the Beckman fellowship and Arnold Beckman had a really inspiring vision. And his vision was, you know, he makes tools that then other people can do science with. That's our goal with the continuous flow work is to put those tools of polymer synthesis that I think are really valuable, because I'm a polymer chemist into other people's hands and allow them to explore structure spaces.
Paolo Braiuca 23:02
How far are we from having this platform ready?
Frank Leibfarth 23:06
So the first application we're targeting is making some MRI imaging agents. And we started with six different monomers. So the total structure space we could possibly make, when we combine these monomers that at 5%. increments is about 65,000 materials. And again, these display interdependent properties, so you add a little bit of one monomer, that increases one parameter, but then you know, lowers another parameter that you're interested in, and it's back and forth. And it's hard to figure out. So now we've developed an instrument that can make one individual polymer sample every two minutes. We've now made over 250 samples. Right now the machine from selecting starting materials to synthesis is all automated. So my student just typed salt, he know he now built this instrument. So he types all this information, the information, the materials he wants into an Excel sheet, uploads that Excel sheet into the software he has and pushes go. Right now, still, we have one of the big challenges is automating purification and automating characterization. We can do that for some properties. But for really interesting properties, I would say that is still a work in progress.
Paolo Braiuca 24:15
It sounds to me you're not that far. It is which is very exciting. So I really look forward to speak to you again in a couple of years. And you'll you'll tell me about this beautiful final platform and how it works and what you can achieve with that.
Frank Leibfarth 24:28
I hope so too.
Paolo Braiuca 24:30
So as we're coming towards the end of our chat let's speak a little bit about your sort of small, daily, technical and maybe personal challenges you face in your work, the things that you know, you need to deal with on a daily basis, you and your team.
Frank Leibfarth 24:47
There's a lot of things to deal with, and then a global pandemic started. So now there are even more challenges to deal with. You know, I'm not too far away from starting as an assistant professor. I just celebrated my four year anniversary. at UNC, so I'll put it in that context, building a lab has been the most exciting and most challenging thing I've ever done. The most important thing that I identified at the beginning and I would say is still the most important thing is building a positive and innovative lab culture. Right, because everything stems from some of the, you know, we have some of the smartest students in the world coming to you and see. And, you know, they're excited about chemistry, they want to innovate. So how do you keep that spark alive? Well, they're going through a growth process, personally, that everybody goes through from the time that they're right 22 to 28, when, you know, they start to focus on one problem really intensely and, and have failures and deal with challenges. So that that has been a big challenge. But that's been a really fun challenge. That's really hard to begin with, both from the student perspective, and from my perspective, figuring out how to manage these people the best figuring out how to fund them through different funding avenues, also learning to teach everything at the same time. But having this all up ended by COVID. And having right stop research, and then start research and have so much uncertainty around this has been especially challenging for, for my students for their research progress, they still want to graduate on time, they're still looking to get jobs, but their resumes are going to be significantly hit. The same goes for me as an assistant professor, it's been challenging for their mental health, I have a 10 month old, it's been challenging, just technically, trying to figure out childcare. It's been challenging for my mental health, dealing with all these things that are coming at me when the job of an assistant professor is already difficult. I would never trade this job for anything, the ability to be creative and work with excited young people is super fun. I never thought I'd have a job this fulfilling as I was growing up in South Dakota, you know, that really always was my goal as I was growing up is I want to I want to have a job that's isn't horrible to go to. My dad drove a semi for for many years when I was growing up. And he never complained. But it was very obvious he didn't enjoy getting up at 4am every day, and getting in that truck. So I saw him. And I was inspired by him but also knew like, you know, my goal in life is to not hate getting up in the morning. And I've achieved that goal, for sure.
Paolo Braiuca 27:23
I can only give you my congratulations. And I'd like to ask you one final thing. You know, you're a very accomplished and successful scientist, despite you're still very young age. And I'm sure you have a bright future ahead of you. What's one piece of advice you'd pass on now to a young chemist, or scientists just starting their career?
Frank Leibfarth 27:46
I think the biggest thing I can say is trust yourself, you will get so much different advice, you will have imposter syndrome, you will see all these other people successful and feel like you're you're being left behind. But in the end, you go through all this training, you in many ways commit large portions of your life to educating yourself in science, it is a calling for those who are committed to it like that, you know best. definitely get advice, right? Lean on mentors, that is really important. But in the end, when it comes to those make or break decisions, you know, best. The thing I think of is pursuing kind of this this research area on asymmetric analysis, I didn't have any experience in asymmetric catalysis. I asked some people and they're like, that seems pretty risky jumping into that area. It's you know, it's not for the faint of heart. But I just some part of me knew that there was something really interesting down that road. And I guess another piece of advice goes along with that. Once you get a job as a professor or industry after your PhD, that does not mean you're done learning. You actually just learned faster. You know, trust yourself and embrace that continued learning because you can continue to get better. And those those skills will just keep building, right. It's not, it's not like you lose any of the skills you've built over over those years. Take the swings. And sometimes they work sometimes they don't. Everybody's career is different. And the nice thing is everybody, there's many different definitions of success in science, if you're if you're committed and if you're flexible, and if you trust yourself, it'll probably work out.
Paolo Braiuca 29:23
That was Dr. Frank Leibfarth, assistant professor of chemistry at UNC Chapel Hill, and one of the Chemical & Engineering News' Talented 12 thanks for joining us for this episode of bringing chemistry to life. A Science with a Twist series. We'll bring you more conversations with the Talented 12 every other week. For new episodes, subscribe wherever you get your podcasts, and you can visit labchemresources.com for more information about Thermo Fisher Scientific Laboratory Chemicals. This episode was produced by Matt Ferris, Gabriel Orama and Emma-Jean Weinstein.