Lab space + creativity:
The two requirements to cultivate great science and great scientists. Accompany us on a journey to uncover new chemical function and understand the complexities of biological interactions through polymer chemistry.
Graduate student Marcus Reis receives the UNC Hiskey Graduate Research Fellowship
A big congratulations to Marcus Reis for receiving the UNC Hiskey Graduate Research Fellowship! The Hiskey Fellowship will cover Marcus’s tuition, fees, and stipend for the Fall 2019 semester. Over the last three years Marcus has dedicated his time to uncovering fundamentals of polymerization in continuous flow, diving into programing to make automated systems utilizing flow chemistry, and innovating experiential programs for undergraduate students at UNC and patients at the UNC Children’s hospital (check out our outreach page!). This past year he developed a course for undergraduate students at UNC to build a “recyclebot” from the bottom up that extrudes excess 3D printer scraps back into filament for reuse. His passion for research and outreach earned him this fellowship, and the group is looking forward to more big things from Marcus!
Congratulations to Jill Williamson (Leibfarth lab), Christina Na (Alexanian lab), Rob Johnson (Leibfarth lab), and Will Daniel (Dingemans lab) for their recent publication in JACS on thermally induced xanthylation of polyolefins! The latest publication of the Leibfarth–Alexanian collaboration further expands photo-initiated polymer C–H xanthylation to include thermally initiated polymer C–H xanthylation, trithiocarbonylation, and dithiocarbamylation. Thermal initiation was transformational to this project as this new series of studies elucidated key steps in the reaction mechanism as well as made reactive extrusion possible, a technique often seen in industrial practices. This paper includes the first report of metal-free chemo- and regio-selective functionalization of isotactic polypropylene, the world’s second largest volume commodity plastic. Upon reactive extrusion, functionalized isotactic polypropylene proved to adhere to glass surfaces twice as strongly as the virgin polymer, indicating the translational potential of this method for plastic upcycling.
Jill has been traveling around the world over the last few months presenting this work at a number of presigious conferences. Jill began the summer presenting “Amidyl Radical-Mediated Polyolefin C–H Functionalization” at the Polymers Gordon Research Seminar (GRS) to fellow graduate students and post-docs in South Hadley, MA. Impressed by her work, GRS attendees voted for her to speak at the corresponding Polymers Gordon Research Conference (GRC) as well. More recently, she presented this work at the Ewha-Luce International Seminar (ELIS) at the Ewha Woman’s University in Seoul, South Korea. Jill participated in the 18-day leadership seminar in Korea, designed to support and encourage female graduate students in science, technology, engineering, and mathematics in the US and Asia. At ELIS, Jill presented her work in a TED-style talk called “Nature & Science” on “Upcycling Plastic Waste”. She also enjoyed learning about Korean culture, eating new food, visiting Jeju, and came back with lots of candy and gifts for the lab!
Sally Lewis (with help from UNC undergraduate Bradley Wilhelmy) has spent the last few years chemically decorating Styrofoam waste. The project began with a simple photoredox mediated trifluoromethylation of polystyrene, which was inspired by the creative work of the Stephenson group at the University of Michigan. To our surprise, this method was incredibly chemoselective, providing fluorinated products that were easy to purify and quantify with no observable polymer degradation. We attribute this high selectivity to the unique reactivity of electrophilic radicals, which would much rather react with aromatic rings than pluck off hydrogen atoms from the polymer backbone. As we began to increase the amount of fluorine incorporated, the polymer became soluble in a range of organic solvents and static water contact angles just kept increasing. This approach also worked on other high volume aromatic polymers, including polycarbonate and polyethylene terephthalate. To further demonstrate the utility of this method, Sally also found that functional units could be attached to the polymers, which enabled the graft-co-polymerization of other materials from the backbone of a commodity polymer. Diversifying the properties of commodity plastics earned this paper the title of Paper of the Week in Chemical Science and was highlighted in Chemistry World (C–H Fluoroalkylation Tackles Plastic Waste).
Frank is one of 10 scholars to be named a 2019 Beckman Young Investigator by the Arnold and Mabel Beckman Foundation. The award, which comes with $600,000 in funding over four years, supports the nation’s most promising young faculty members in the early stages of their academic careers in the chemical and life sciences, particularly to encourage work that opens up new avenues of research.
The Beckman Young Investigator Award will fund work in the group focused on developing the next-generation of sustainable plastics. The majority of current plastics are derived from petrochemical resources and persist in the environment long after their useful lifetime. While these materials would ideally be replaced by plastics that are both derived from renewable resources and degrade into environmentally benign byproducts, the majority of current sustainable alternatives do not have the properties to compete with petroleum-derived materials.
The group will use the Beckman Young Investigator funding to develop a new approach toward the production of sustainable plastics with the potential to dramatically enhance their mechanical properties. Dr. Aaron Teator in the group has recently discovered a new concept to control polymer stereochemistry using asymettric ion-pairing catalysis. Translating this concept to building blocks that are derived from biorenewable substrates such as corn, mint and trees will yield next-generation plastics with a significantly smaller environmental footprint. Additionally, the production of these high-value materials from renewable building blocks will result in plastics that are considerably easier to degrade either chemically or in the environment.
The Arnold and Mabel Beckman Foundation supports researchers and nonprofit research institutions in making the next generation of breakthroughs in chemistry and the life sciences. The list of current and past awardees of the Beckman Young Investigator comprise some of the most creative scientists conducting interdisciplinary research int he U.S.
Aaron Teator took a chance to begin his postdoc in our newly formed lab. He began working on an ambitious project to harness chiral anions to control the stereoselectivity of cationic polymerizations. The challenges were many, but Aaron overcame each of them to discover a method for the polymerization of a class of isotactic poly(vinyl ether)s. These materials have similar mechanical properties to commercial polyolefins but adhere to class 14 times stronger than low-density polyethylene.
We took inspiration from previous work in the field of asymmetric catalysis to design catalysts that control the facial addition of each monomer unit to the reactive polymer chain end. This enabled the realization of a general method for the synthesis of isotactic poly(vinyl ether)s. After the synthesis of these materials, we quickly noticed their impressive material properties. They felt exactly like a sheet of polyethylene, yet they stuck strongly to the vials in which we isolated them. After quantitative tensile testing, we determined that they had almost identical mechanical properties to commercially available samples of low density polyethylene but adhered to glass 14 times stronger than commodity polyolefins. We hope both the concept of chiral counterion catalysis for stereoselective polymerization and the utility of isotactic poly(vinyl ether)s will benefit the scientific community.
Marcus and Travis collaborated to determine how fluid dynamic phenomenon inherent to tubular microreactors affect polymer composition and structure in continuous flow polymerizations.
Summary: Continuous-flow chemistry is emerging as an enabling technology for the synthesis of precise polymers. Despite recent advances in this rapidly growing field, there remains a need for a fundamental understanding of how fluid dynamics in tubular reactors influence polymerizations. Herein, we report a comprehensive study of how laminar flow influences polymer structure and composition. We found that the breadth of the RTD has strong, statistical correlations with reaction conversion, polymer molar mass, and dispersity for polymerizations conducted in continuous flow. These correlations were demonstrated to be general to a variety of different reaction conditions, monomers, and polymerization mechanisms. Additionally, these findings inspired the design of a droplet flow reactor that minimizes the RTD in continuous-flow polymerizations and enables the continuous production of well-defined polymer at a rate of 1.4 kg/day.
Frank has recently been selected to receive the Young Investigator Prize (YIP) from the Army Research Office. YIP awards are one of the most prestigious honors bestowed by the Army on outstanding scientists beginning their independent careers. The objective of the YIP is to attract outstanding young university faculty members to pursue fundamental research in areas relevant to the Army, to support their research in these areas, and to encourage their teaching and research careers.
The Army Research Office bestowed Professor Leibfarth this award for his work making plastics with emergent properties from readily available building blocks. To accomplish this task, the Leibfarth group is seeking to use concepts derived from the stereoselective synthesis of small-molecule pharmaceuticals and apply them to the production of next-generation plastics. The three-year award will provide $360,000 to fund research on developing new synthetic methods toward these materials and testing their properties for applications in high-value composites, blends, adhesives, and more.
Our group is working hard to understand where and why methods for the C–H Functionalization of Commodity Polymers will be important. We have some ideas…and we also recognize the significant contributions made in the field by many scientists. To share our thoughts with the rest of the community and demonstrate the breadth of this field, Jill, Sally, Rob, and Irene compiled a Minireview on the subject. We hope you enjoy reading about a field that will think will make significant contributions to polymer science in the coming future.
Short Summary: Synthetic manipulation of polymer substrates is one of the oldest and most reliable methods to increase the functional diversity of soft materials. Modifying the chemical structure of polymers that are already produced on a commodity scale leverages the current high-volume and low-cost production of commodity plastics for the discovery of modern materials. This Review discusses the historical significance of and contemporary advances in the C–H functionalization of commodity polymers. The conceptual approach outlined herein presents exciting new directions for the field, including increasing the value of otherwise pervasive materials, uncovering entirely new material properties, and a viable path to upcycle post-consumer plastic waste.
Jill Williamson, a third year in the Leibfarth Group, was one of four UNC Graduate Students to receive the Clare Boothe Luce Fellowship! The $300,000 grant for which Jillian Dempsey is the principal investigator and director, supports three new graduate fellowships for women in chemistry at UNC-Chapel Hill. The fourth fellowship is provided by UNC. The fellowships will be used to support and nurture women graduate students who are aspiring to tenure-track academic positions.
Since its first grants in 1989, the Clare Boothe Luce Program has become one of the single most significant sources of private support for women in science, mathematics and engineering.
Clare Boothe Luce, the widow of Henry R. Luce, was a playwright, journalist, U.S. Ambassador to Italy and the first woman elected to Congress from Connecticut.
In her bequest establishing this program, she sought “to encourage women to enter, study, graduate and teach” in science, mathematics and engineering. Thus far, the program has supported over 2,300 women.
The second paper from the Leibfarth Group is live in Angewandte Chemie International Edition!
The Leibfarth group is thrilled to announce the publication of another manuscript! The paper is entitled “Regioselective C–H Xanthylation as a Platform for Polyolefin Functionalization” and can be found in the latest edition of Angewandte Chemie International Edition. This work is the first of a burgeoning collaboration between the Leibfarth and Alexanian labs at UNC Chapel Hill.
In this manuscript, Jill Williamson of the Leibfarth group and Will Czaplyski from the Alexanian lab develop a platform C–H functionalization methodology to functionalize commodity polyolefins with xanthate functional groups. The use of a reagent originally developed by the Alexanian group for the functionalization of complex small molecules allowed the selective functionalization of secondary or primary carbon sites along the polymer backbone. This enabled a tunable degree of polymer functionalization without deleterious chain-scission or chain-coupling side-reactions.
This project has a short history…but both Jill and Will knew each other long before they became collaborators as alumni of the College of William and Mary. Soon after we initiated the project in April 2017, we immediately realized that this might be one of the most efficient and versatile functionalization methods of branched polyolefins in the literature. By the time we got the results of commercial polyolefins such as high density and linear low-density polyethylene in November, we had already proven that the xanthate can be transformed into a wide-variety of useful functionality. Even though Will recently graduated and moved onto another town covered in red brick (Boston), he and Jill laid the foundation for an exciting and rapidly expanding collaboration between the two groups. You can expect more polymer C–H functionalization chemistry to be emanating from Chapel Hill in the near future!
The Leibfarth Group participates in the 10th annual Triangle Soft Matter Workshop
The Leibfarth group represented itself well at the 10th annual Triangle Soft Matter Workshop at NC State University. The workshop, annually alternating between NC State, Duke, and UNC, featured soundbites and poster presentations by students and postdocs, invited lectures by members of the three participating universities, and a plenary lecture by Professor Christopher Bowman of the University of Colorado at Boulder.
The Leibfarth group presented five soundbites and their corresponding posters this year, with contributions from Marcus, Sally, Jill, Travis, and Aaron. Furthermore, Frank gave an invited lecture in the afternoon entitled "New Approaches to Polar Polyolefins." The groups thanks the organizers for a fantastic meeting and looks forward to next year's event at Duke University!
Three members of the Leibfarth Group receive NSF fellowship honorable mention
Three second year graduate students in the Leibfarth group received honorable mention for the NSF graduate research fellowship program. Sally Lewis, Jill Williamson, and Travis Varner all submitted compelling applications to the NSF GRFP program encompassing their research and outreach endeavors and future plans. This recognition puts Jill, Sally, and Travis in the top 30% of the 12,000+ applications to this competitive program. Congratulations all!
A comprehensive list of awadees can be found here: link.
The first paper from the Leibfarth group, entitled "Continuous-flow chemistry for the determination of comonomer reactivity ratios" has been published in Polymer Chemistry. The group was proud to contribute this manuscript as part of Polymer Chemistry's Emerging Investigators themed issue, which includes an impressive array of young scientists in the international polymer science community.
In this manuscript, Marcus Reis (along with his UNC undergraduate collaborator Cullen Davidson) developed an operationally simple flow system to rapidly determine comonomer reactivity ratios. Key to this method is the ability to systematically vary comonomer composition in situ by varying flow rates to produce nine copolymer samples in a single flow experiment. This high throughput synthesis is an advantage of flow chemistry compared to analogous reactions run in batch and allowed us to validate our approach by determining five reactivity rations with good agreement to literature values and three previously unknown comonomer reactivity ratios.
One of the most impressive aspects of this work was not able to be included in the written manuscript. As is common when constructing a new flow system, many different aspects of the engineered system had to be optimized to make it function reliably. Due to the tight timeline of this invited manuscript, Marcus finally made the last tweaks only two weeks before the due date. Marcus was able to take advantage of the high throughput nature of the flow system to make and analyze 90 copolymers of varying comonomer compositions in two weeks! This was a true tipping point for flow chemistry within the group, and we are now looking to take advantage of high throughput copolymer synthesis for a number of contemporary challenges in biomedicine and materials science.
Dr. Aaron Teator wins the paper of the year competition, breaking Sally's winning streak
Dr. Aaron Teator won the second annual Leibfarth group Paper of the Year competition for his presentation on the paper "Crystal Structure Determination of the Pentagonal-Pyramidal Hexamethylbenzene Dication" (Angew. Chem. Int. Ed. 2017, 56, 368). The competition was hotly contested, with six excellent presentations splitting votes. For his efforts, Aaron received the highly coveted "Curios [sic] Henry: Limited Edition 1996" award. He has promised not to break it (unlike previous winners of the award). On another note, this marked Sally's first loss in any group competition. She has vowed to reassert her dominant performance during the Summer 2018 Method of the Year challenge. The week concluded with the group Christmas party and gift exchange. Luckily Frank was able to secure the Voodoo doll and ensure no black magic will plague him in the coming year.
Frank was honored during Homecoming weekend at the University of South Dakota with the Emerging Leader Award from the USD Alumni Association. The recognition honors an alum who has graduated within the last ten years that best exemplifies leadership in public service or professional accomplishments. The award recognized Frank's achievements throughout his young scientific career. A large group of family and friends were on hand for the event, making it a particularly special reunion.
Three of Frank's mentors and friends helped make a video commemerating the event. The weekend was even more exciting because the Coyotes defeated Youngstown State by kicking a field goal as time expired. Frank, being a former USD kicker, was especially thrilled.
The Leibfarth group receives funding from the Air Force Office of Scientific Research!
Professor Leibfarth is one of 43 scientists and engineers from 37 research institutions and small businesses who has been selected to receive an award from the Air Force's Young Investigator Research Program, YIP. The Air Force Office of Scientific Research has announced it will award approximately $19.1 million in grants to those who submitted winning research proposals. Frank will receive the grant over a 3-year period totaling $450,000.
The YIP is open to scientists and engineers at research institutions across the United States who received Ph.D. or equivalent degrees in the last five years and who show exceptional ability and promise for conducting basic research.
The objective of this program is to foster creative basic research in science and engineering, enhance early career development of outstanding young investigators, and increase opportunities for the young investigators to recognize the Air Force mission and the related challenges in science and engineering.
Press Release highlighting Leibfarth Group work with UNC Wonder Connection
An article highlighting our group's work at the UNC Maker Space was released. The article highlighted Marcus Reis, a second year graduate student in the group, and his work with Ollie making a hydraulic powered robotic arm. Marcus and Ollie met through UNC Wonder Connection and Ollie has been visiting the lab each week during the summer to complete the project. Marcus and Ollie took advantage of the 3D printing and laser cutting facilities in the UNC Maker Space for their final prototype.
Marcus and Ollie plan to make their project into a "kit" that other UNC Wonder Connection volunteers can use to build simple robots with patients at the UNC Children's hospital. This work is part of the Leibfarth Group's partnership with UNC Wonder Connection, a non-profit, one-of-a-kind program that provides pediatric patients with a connection to the natural world via hands-on natural science activities. .
Leibfarth Group Coordinates Event with the UNC Wonder Connection
The Leibfarth group recently organized and put on a scientific outreach event at the Ronald McDonald House of Chapel Hill. The group, in partnership with the UNC Wonder Connection, set up three hands-on science demonstrations to educate and excite children and parents alike about chemistry and polymer science. The UNC Wonder Connection is an organization run through the UNC Botanical Garden with a mission to empower pediatric patients with the wonders of nature and science through multi-sensory learning experiences that promote joy and well-being. More information can be found here. Our groups seeks to both complement their existing efforts and help expand their organizational scope to include chemistry- and polymer-specific programing.
The group is excited to continue working with patients and the Wonder Connection through a combination of individualized and large-group engagements. We seek to engage and empower pediatric patients by unlocking their scientific creativity, increasing their scientific knowledge, and acting as an inspiration for their futures.
Professor Frank Leibfarth, a recent addition to our faculty, is the recipient of the 2017 3M Non-tenured Faculty Award.
The award recognizes outstanding new faculty, nominated by 3M researchers and selected based on their research, experience, and academic leadership. The award encourages the pursuit of new ideas among young faculty and gives them an opportunity to interact with their peers and 3M scientists at the annual 3M Faculty Appreciation Day.
Professor Leibfarth received the award for his proposal entitled “Biorenewable Fluorine-Containing Polymers.” In addition to the honor, the award provides $15,000 per year for three years to support research efforts. The purpose of the award is to help young faculty achieve tenure, remain in their teaching position, and conduct research. This award is administered by 3M’s Research and Development Community in partnership with 3Mgives.
Group Christmas Party & Paper of the Year Competition
The group had their first annual "Paper of the Year" competition & Christmas Party. After 5 entertaining presentations and a contentious vote, Sally Lewis won the competition by convincing the attendees that "A bacterium that degrades and assimilates poly(ethylene terephthalate)" was the paper of the year. For her efforts, Sally received the highly coveted "Curios [sic] Henry: Limited Edition 1996" award. After the competition, the group ate, drank, played games, & had a fitting send off to an exciting 1st semester.
When the UNC public relations department was brainstorming stories for their back-to-school media, they ran across one of Frank's tweets about his first delivery to the lab. While they usually focus on students coming back-to-school, they realized that few undergraduates on campus realize that a new crop of faculty is also moving in!
The team stopped by the lab numerous times through the summer as things were getting started and they documented the process quite accurately in the following story and accompanying photoessay. We've come a long way AND we are just getting started. Exciting times!
Frank is absolutely ecstatic to announce that he will join the UNC Department of Chemistry as an Assistant Professor. UNC has a strong tradition as a premier institution of higher education and the reputation and bright future of the Chemistry Department is an ideal infrastructure for a young scientist. Frank is excited to set up his new lab and work with the many great students and colleagues within the UNC community. Research in the Leibfarth group will focus on polymer science, spanning each stage from molecular design and synthesis to material function. The program will provide students with a diverse and competitive skill set bridging organic and polymer synthesis, small molecule and macromolecule characterization, and applied studies in materials science and biotechnology.
Frank wins the RSC Best Poster Prize at the Continuous Flow Chemistry Zing Conference!
Frank's poster, entitled "Flow IEG: Scalable Synthesis of Sequence and Architecturally Defined, Unimolecular Macromolecules," won the RSC best poster prize the the Continuous Flow Chemistry Zing Conference held in Alburfeira, Portugal. The speakers at this biannual conference was outstanding and Frank was humbled to be honored by such an excellent group of scientists.
Watch Frank's TEDxUSD lecture now on YouTube
Frank TEDx lecture entitled "Rise of the Machines: How automated polymer synthesis will accelerate the pace of scientific discovery" at the TEDxUSD event was held on Saturday, Nov. 7th at the University of South Dakota's historic Farber Hall. Listen to Frank describe his research at MIT on automated polymer synthesis.
Alex Albanese interviewed Frank for the first episode of his new podcast; Glimpse is a podcast created and produced by Alex where he seeks to learn about the research going on at MIT by speaking to postdocs on the "front lines." In this episode, Alex and I discuss the power of ketenes, polymers, and continuous flow chemistry. We also talk about the crucial difference between table salt and sodium hydroxide (hint: I learned this the hard way as an undergraduate researcher). Alex is a postdoc working in the Laboratory for Multiscale Regenerative Technologies in the Koch Institute for Integrative Cancer Research for Professor Sangeeta Bhatia. Subscribe to Glimpse to learn more about the research going on at MIT and listen to my episode here: link.
Frank's recent paper published in the Proceedings of the National Academy of Sciences USA [Scalable synthesis of sequence-defined, unimolecular macromolecules] has been highlighted in a full page article in the August 24th edition of Chemical & Engineering News, the weekly magazine published by the American Chemical Society. The article, written by Stu Borman, contains quotations from preeminent polymer scientists Prof. Craig J. Hawker and Prof. Jean-Francois Lutz.
Frank's paper on continuous flow systems for polymer synthesis published
The manuscript describing Frank's postdoctoral research has recently appeared online. The paper, entitled "Scalable synthesis of sequence-defined, unimolecular macromolecules" is published in the Proceedings of the National Academy of Sciences USA.
The paper describes our work to expedite polymerization processes empowered by the convergence of multi-step continuous flow chemistry and iterative exponential growth (Flow-IEG). The user-friendly nature, scalability, and modularity of Flow-IEG provides a general strategy for the automated synthesis of sequence and architecturally defined, uniform macromolecules. We envision this polymer synthesis machine will serve as an enabling tool for both fundamental explorations and advanced applications in biotechnology, medicinal chemistry, and materials science.