Taking Aim at Plastic Waste

Taking Aim at Plastic Waste

UD wins federal grant to establish Center for Plastics Innovation

Every year millions of tons of plastic bottles, coffee cups, grocery bags and other waste enter our environment, from landfills to vast garbage patches in the ocean. These plastics can persist for decades, posing health threats to humans and wildlife.

Think about how the entire planet would benefit if more of this plastic could be recycled or reimagined instead of trashed.

The Center for Plastics Innovation (CPI), a new research center at the University of Delaware, is now taking aim at that challenge. Funded by an $11.65 million grant from the U.S. Department of Energy, CPI is one of six new Energy Frontier Research Centers (EFRCs) established across the U.S. to accelerate scientific breakthroughs in critical areas.

CPI will bring together researchers from UD, the University of Chicago, University of Massachusetts Amherst, University of Pennsylvania and Oak Ridge National Laboratory to “upcycle” plastic waste — chemically transforming it into fuels, lubricants and other valuable products in an energy-efficient manner.

UD’s LaShanda Korley, Distinguished Professor of Materials Science and Engineering and Chemical and Biomolecular Engineering, will lead the effort. Thomas H. Epps, III, UD’s Thomas and Kipp Gutshall Professor of Chemical and Biomolecular Engineering, will serve as co-director.

“Thanks to the exceptional leadership of Professors Korley and Epps, this new Center for Plastics Innovation will be a dynamic force for breathing new life into otherwise wasted materials and energy, thus tackling one of the most important challenges facing our world,” said UD President Dennis Assanis. “The University of Delaware’s researchers and students will be trailblazers in this critical field, making transformative contributions to the environmental health and sustainability of our planet. We wish this exceptional team, and all of its partners, great success with the exciting work ahead.”

As an Energy Frontier Research Center, UD’s Center for Plastics Innovation will play an important role in advancing the nation’s energy future.

“The EFRC program has been one of our most innovative and successful basic science research efforts, driving progress in a wide range of important scientific fields,” said U.S. Secretary of Energy Dan Brouillette.  “Through these research centers, the Department is mobilizing America’s scientific workforce to lay the foundation for the nation’s future energy innovation, security and prosperity.”

Upcycling plastic waste

Worldwide, more than 350 million tons of plastics were produced in 2018 alone. Only 12% of this plastic waste is reused or recycled, according to an industry report. Current recycling strategies fall far short in recovering material that is as high in quality as the material you started with — a major hurdle the CPI will be working to overcome.

Plastics are formed from polymers, which are chemically bonded chains of repeating units called monomers. These monomers, made up of atoms of carbon, hydrogen, oxygen, nitrogen, chlorine, sulfur and other elements, are the raw materials of plastics manufacturing.

The CPI team is focusing on the most difficult plastics to recycle because of their complex chemical structure. Examples include high-density polyethylene (HDPE), used in containers for milk, motor oil, shampoo and bleach; low-density polyethylene (LDPE) found in sandwich bags and plastic grocery bags; polystyrene used in Styrofoam coffee cups and other food packaging; and poly (methyl methacrylate) (PMMA), from which acrylic sheets such as Plexiglas are made.

“We have a unique skill set at Delaware, with strengths in catalysis, polymer science, computational design, synthetic biology and machine learning,” Korley said. “Our collaborators and partners bring great expertise in computational materials science and enzymatic catalysis, and also contribute characterization and computational facilities critical to advancing this work.”

The CPI team initially will investigate fundamental catalytic and functionalization approaches on the pristine polymers that comprise these plastics waste streams — processes that add new features or capabilities by altering the polymers’ surface chemistry. Then, the team will begin building various levels of complexity into the plastics, such as adding a colorant or a layered configuration, to test strategies on more realistic feedstocks.

In consultation with advisers from industry, academia and the National Institute of Standards and Technology (NIST) in the U.S. Department of Commerce, the team will pursue traditional and additive manufacturing techniques to simulate the manufacturing process of actual products, from a simple flat plastic film to fully dimensional Lego-like objects.

The team will apply different strategies to break down plastics waste — using chemical catalysts and selective enzymes — to “de-polymerize the polymers” and recover pure material for making high-value fuels and lubricants at low temperature. Other catalytic strategies will be explored to transform the recovered materials by changing their electronic properties or by incorporating a “stealth catalyst,” for example, that would activate only on demand.

It is challenging work, in which the power of partnerships can really make a difference.

At UD, researchers from multiple departments will be involved — Materials Science and EngineeringChemical and Biomolecular EngineeringChemistry and Biochemistry, and Electrical and Computer Engineering — as well as the Delaware Energy Institute.

“This center brings together a highly collaborative and multifaceted team in order to provide transformative solutions to a critical problem impacting the environment,” Epps said.

Levi Thompson, dean of the UD College of Engineering, said this new center further cements the college’s status as a destination for talented people to collaboratively tackle important societal problems.

“We have deliberately worked to create a culture and climate that supports and celebrates innovation,” said Thompson. “LaShanda and Thomas have assembled an outstanding team that will, for many years, help improve the quality of life for everyone through research on polymeric and other soft materials.”

UD: A place for frontier research

The new center stands to impact UD and the broader community in numerous positive ways, according to Charles G. Riordan, vice president for research, scholarship and innovation.

“The Center for Plastics Innovation will advance solutions to the global plastics pollution crisis through ingenuity and teamwork,” Riordan said. “As an Energy Frontier Research Center — the second to be established at UD — CPI will bring together established and early career faculty to inspire creative solutions while also providing our students with valuable research experiences and opportunities for industry collaboration.”

UD’s existing EFRC, the Catalysis Center for Energy Innovation, directed by Dion Vlachos, the Allan and Myra Ferguson Professor of Chemical and Biomolecular Engineering, was established by the U.S. Department of Energy in 2009. The center has developed processes for transforming biomass such as wood chips and switchgrass into sugars and oils for use in products ranging from chemicals to advanced materials.

“CPI’s formation is exciting as it can profoundly impact one of our major ecological and societal problems and is a culmination of UD’s collaborative culture and the leadership of our polymers colleagues,” Vlachos said.

Korley credits the collaborative nature of UD’s research community as a key contributor to the funding success of both the Center for Plastics Innovation, and of UD’s recently announced Center for Hybrid, Active and Responsive Materials (CHARM), funded by an $18 million grant from the National Science Foundation.

“What is great about Delaware is that when I arrived two-and-a-half years ago, several faculty members began conversations about core research strengths and interests, and we started to brainstorm,” Korley said. “This collaborative atmosphere really allowed these ideas to take off. We are excited to launch these ideas from concepts to fundamental scientific advances with the ability to transform the state of our environment.”

The Center for Plastics Innovation team would like to offer a special thanks to Joy Mintzer, senior sponsored program coordinator in the College of Engineering, and Jaynell Keely of the Delaware Energy Institute, for proposal support.

| Graphic illustration by Christian Derr

$18 Million for UD center to advance materials research

$18 Million for UD center to advance materials research

Federally-funded center to advance materials research

A new center at the University of Delaware will advance research to transform the way materials are made.

The UD Center for Hybrid, Active, and Responsive Materials (UD CHARM) will drive fundamental materials science research with the potential to enable critical innovations in biomedicine, security, sensing and more.

The effort will be led by UD’s Thomas H. Epps, III, the Thomas and Kipp Gutshall Professor of Chemical and Biomolecular Engineering, with $18 million in funding from the National Science Foundation. Epps also holds a joint appointment in materials science and engineering. LaShanda Korley, Distinguished Professor of Materials Science and Engineering and Chemical and Biomolecular Engineering, will co-direct and coordinate operational aspects of the center.

The center is part of a network of academic partners and national labs focusing on the development of new materials. Regional research partners in the UD-led center include the University of Pennsylvania and the National Institute of Standards and Technology (NIST). It is one of 11 Materials Research Science and Engineering Centers (MRSECs) across the country funded by the NSF in 2020.

MRSECs are an important part of the materials science enterprise in the United States with a focus on fundamental research. They serve as hubs for national and international collaboration in research and industry partnerships, and also are critical developers of educational and outreach content for the materials community.

“We congratulate Professors Thomas Epps and LaShanda Korley for leading this transformational effort,” said University of Delaware President Dennis Assanis. “The new Center for Hybrid, Active, and Responsive Materials at UD will expand the boundaries of science and engineering and spearhead the materials revolution that will help create the future economy. The center will bolster our research and academic partnerships with Delaware State University and with Claflin University to provide more educational opportunities to students from underrepresented groups. We look forward to the exciting developments ahead by this amazing team!”

A major educational and outreach thrust of UD CHARM will be to improve the diversity landscape at all levels of the academic and research enterprise. Key initiatives include providing exciting research and education opportunities in materials science for students from underrepresented groups, in partnership with Delaware State University in Dover, Delaware, and Claflin University in Orangeburg, South Carolina, two historically black colleges and universities (HBCUs).

“This award not only provides a home for new research in our region, but it will allow students access to funding and opportunities and make these regional partners an even more attractive destination for top scientists,” said U.S. Sen. Chris Coons from Delaware, who is a staunch supporter of science and a member of the Commerce, Justice, and Science Appropriations Subcommittee.

Enabling ultra-small building blocks

UD CHARM is advancing foundational understanding of new materials driven by theoretical and computational predictions paired with cutting-edge experiments. The collaborative effort involves interdisciplinary teams of UD faculty from chemical and biomolecular engineeringmaterials science and engineeringphysics and astronomy, and chemistry and biochemistry.

One project team, led by UD researchers Darrin Pochan and April Kloxin, will work to design synthetic and artificial versions of proteins that can act as molecular scaffolds and, ultimately, as ultra-small molecular robots and devices. The hope is to program these molecular machines to perform functions that are difficult to accomplish with human hands, such as locating and soldering a loose wire on a computer chip inside a device or moving cellular material from one location to another inside the body.

The center will leverage expertise in computational science with Jeff Saven at the University of Pennsylvania to streamline the experiments driving this work and invest in advanced materials characterization equipment to make these devices. The partnership with NIST, a national laboratory, affords researchers involved in this effort the ability to directly study these machines at work in the environment where they will be used, rather than in an artificial environment like a petri dish.

“As a member of the network of Materials Research Science and Engineering Centers, UD will serve as an international hub for collaboration in research and industry partnerships, as well as developers of educational materials for the materials community,” said Charles G. Riordan, UD’s vice president for research, scholarship and innovation. “These facilities and capabilities will benefit the University community, as well as local industry and regional academic partners.”

A second project team, headed by UD materials scientists Joshua Zide and Matthew Doty, will focus on designing next-generation quantum materials and devices that can improve our ability to sense everything from chemical weapons, such as anthrax, to viruses or changing oxygen levels in humans.

To do so will involve creating precise, high-quality and high-purity materials to develop and validate new theories in physics. In turn, these theories will enable faster, cheaper, more sensitive and more reliable sensors, energy conversion devices and computing approaches.

“These interdisciplinary efforts build upon UD’s core strengths in materials research and will drive new innovations that will have transformative impact in technology and education,” said Korley.

Improving diversity, climate and community

To help build a diverse and inclusive pipeline of future engineers and scientists, UD CHARM will support undergraduate pathways for Black and Latinx youth. This will include paid internships through TeenSHARP-DE, a college prep program, along with other mentoring initiatives to expose younger students in basic science and engineering.

According to Epps, one particularly exciting component of the partnership with DSU and Claflin University is the MRSEC fellows program, which will create a pathway to graduate school for undergraduate students by exposing them to materials science early on in their college careers. DSU, for example, does not offer a materials science degree program. Through the MRSEC fellows program, DSU and Claflin students will have the opportunity to participate in UD undergraduate research opportunities and materials science courses at no cost to them, with the goal of furthering their educational objectives and curiosity.

Annually, the center will support approximately 40 undergraduate and graduate students and postdoctoral researchers, along with five high school students over the six-year grant.

“Coupled with networking and mentoring opportunities, students will be able to envision themselves in these spaces, and find trusted resources and role models for guidance,” said Epps.

Along with Epps and Korley, UD co-principal investigators and technical leads on the project include:

  • Matthew Doty, professor of materials science and engineering;
  • April Kloxin, Centennial Development Professor of Chemical and Biomolecular Engineering, with a joint appointment in materials science and engineering;
  • Darrin Pochan, professor and chair of materials science and engineering; and
  • Joshua Zide, professor of materials science and engineering.

The UD CHARM team would like to offer special thanks to David Barczak, communications manager in the UD Research Office, and Joy Mintzer, senior sponsored program coordinator in the College of Engineering, for their proposal support.

| Graphic illustrations by Don Shenkle

Aqua Plants

Aqua Plants

UD research shows that submerged vegetation helps to offset Chesapeake Bay acidification

For many years, the world’s oceans have suffered from absorbing human-made carbon dioxide from the atmosphere, which has led to the decreasing pH of saltwater, known as ocean acidification, and threatened the health of marine organisms and ecosystems. While this process has been well documented, the acidification process is complicated and poorly understood in coastal waters.

For example, the main stem of Chesapeake Bay, the largest estuary in the east coast, has suffered from low oxygen and acidification for years in its bottom waters. Unlike ocean waters, acidification in estuaries like Chesapeake Bay is driven by both fossil fuel-derived carbon dioxide as well as carbon dioxide released from the intense decomposition of algae spurred by nutrient inputs from surrounding land. Although scientists are improving their understanding of the causes of acidification, the ways in which coastal waters like Chesapeake Bay fight back and resist acidification are less known.

Photosynthesis by the plants in submerged aquatic vegetation (SAV) beds can remove nutrient pollution in the bay, can generate very high pH, and elevate the carbonate mineral saturation state, which facilitates the formation of calcium carbonate minerals. When these calcium carbonate particles and other biologically produced carbonate shells are transported downstream, they enter acidic subsurface waters where they dissolve.

One possible way the Chesapeake Bay is combating ocean acidification comes in the form of an already present ally: submerged aquatic vegetation (SAV). While there was a bay-wide decline of SAV from the 1960s through the 1980s, restoring these once-abundant SAV beds has been a primary outcome of efforts to reduce loads of nutrients and sediments to the estuary and SAV cover has increased by 300 percent from 1984 to 2015.

One of the largest recovered SAV beds lies in an area of the bay known as the Susquehanna Flats — a broad, tidal freshwater region located near the mouth of the Susquehanna River at the head of the bay.

The University of Delaware’s Wei-Jun Cai was part of a research group that recently conducted a study of the bay, including in the Susquehanna Flats, in order to understand how the Chesapeake Bay uses a defense mechanism against acidification – known as buffering – to help reduce carbon dioxide and acidification in its waters during the summer time.

The research team included researchers from Xiamen University in China, St. Mary’s College, Oregon State University and the University of Maryland Center for Environmental Science’s Chesapeake Biological and Horn Point Laboratories.

They found that strong photosynthesis by the plants in SAV beds at the head of the bay and in other shallow, nearshore waters can remove nutrient pollution in the bay, can generate very high pH, and elevate the carbonate mineral saturation state, which facilitates the formation of calcium carbonate minerals. When these calcium carbonate particles and other biologically produced carbonate shells are transported downstream, they enter acidic subsurface waters where they dissolve.

This dissolution of the carbonate minerals helps to “buffer” the water against pH decreases or even support pH increases. “Just like people take Tums to neutralize the acids that cause heartburn, the idea is that SAV beds send carbonate minerals to the lower Bay to neutralize acids there,” said Jeremy Testa of the University of Maryland Center for Environmental Sciences and a co-author of the study.

The research was recently published in Nature Geoscience. The first author, Jianzhong Su, was a UD-Xiamen University Dual Degree doctoral student and had Cai as an adviser.

Calcium carbonate dissolution

In previous work, Cai, the Mary A.S. Lighthipe Professor in the School of Marine Science and Policy in UD’s College of Earth, Ocean and Environmentshowed there was a lot of calcium carbonate dissolution in the subsurface water of the lower bay but they didn’t know where that carbonate was coming from.

“This paper shows unique evidence that the carbonate comes from these submerged aquatic vegetation beds,” said Cai. “Shallow waters in the upstream heads and nearshore areas can have a vast amount of submerged aquatic vegetation.”

Wei-Jun Cai is the Mary A.S. Lighthipe Professor in the School of Marine Science and Policy in UD’s College of Earth, Ocean and Environment.

In these areas during summer time, sunlight combines with nutrients to allow dense SAV beds to initiate high rates of photosynthesis that causes the pH in the water to increase, meaning the water is less acidic.

Because the pH is so high, the researchers were able to collect and measure the carbonate particles on the surface of the leaves, which they could scrape and analyze. Co-authors Chaoying Ni, professor in UD’s Department of Materials Science and Engineering and Director of the W.M. Keck Center for Advanced Microscopy and Microanalysis, and Yichen Yao, who was a master’s level student in materials engineering, did the mineral analysis.

“The lab did an image for us and showed the carbonate in these sediments and the sediment on the leaves, the particles, their concentration was a lot higher than the bottom sediment,” said Cai.

Theoretical carbon formations

When the researchers went to a shallow area upstream of the Susquehanna Flats, they also found the carbonate, which led them to their theory that the carbonate forms in one location, particularly, in the SAV bed of the Susquehanna Flats, and then it’s transported to the lower bay.

“We know there is a lot of carbonate dissolution in the lower bay, and we know the upper bay is where the carbonate is formed. So in the paper, we hypothesize that it’s that formation in the SAV bed that gets transported downstream and dissolves and we reproduce this downstream transport with a numerical model,” said Cai. “This carbonate that is transported from upstream actually acted as a way to resist, to buffer the pH of the system.”

While there was a bay-wide decline of submerged aquatic vegetation (SAV) from the 1960s through the 1980s, restoring these once-abundant SAV beds has been a primary outcome of efforts to reduce loads of nutrients and sediments to the estuary and SAV cover has increased by 300 percent from 1984 to 2015. One of the largest recovered SAV beds lies in an area of the bay known as the Susquehanna Flats—a broad, tidal freshwater region located near the mouth of the Susquehanna River at the head of the bay.

There are important ecological ramifications of this finding in that coastal nutrient management and reduction not only help to fight against low oxygen stress but also acidification stress to the environments and organisms that live there via the resurgence of submerged vegetation.

Cai said that while their preliminary results are encouraging, the next steps are to determine if the carbonate particles are really transported by the currents and tides to the lower bay and if so, how fast and under what conditions this happens. He wants to go back to the Bay to nail down the missing link between where the carbonate forms and where it dissolves.

“This is a very interesting thing,” Cai said. “People talk about ocean acidification and very rarely talk about what resists it, what can buffer the system against ocean acidification. So that’s what we want to find.”

| Photos by courtesy of Wei-Jun Cai and Jeremy Testa |

Engineering Honor for LaShanda Korley

Engineering Honor for LaShanda Korley

Professor named Fellow of American Institute for Medical and Biological Engineering

LaShanda Korley’s lab at the University of Delaware has an unofficial motto: The Korley Lab — where unicorns are real. The fanciful motto represents an undeniable truth. By creating new materials inspired by nature for applications in healthcare, sensing, soft robotics and more, Korley is pushing the boundaries of what materials scientists and engineers previously thought possible.

For outstanding contributions to bio-inspired materials design and manufacturing, Korley, Distinguished Associate Professor of Materials Science and Engineering and Chemical and Biomolecular Engineering at the University of Delaware, has been named to the College of Fellows of the American Institute for Medical and Biological Engineering (AIMBE).

Election to the AIMBE College of Fellows is among the highest professional distinctions accorded to a medical and biological engineer. The College of Fellows consists of the top two percent of medical and biological engineers. Korley is one of 156 new Fellows being inducted in 2020.

“I am extremely honored to be elected to the 2020 Class of AIMBE Fellows,” said Korley. “The recognition by such an esteemed engineering community is particularly important to me, as it highlights the impact and relevance of my research lab’s focus on bio-inspired strategies to develop mechanically-robust and responsive soft material systems with applications from tissue engineering scaffolds to gradient coatings. It also reinforces how blessed I am to have such a talented team of researchers – past and present — in my lab.”

Korley leads a laboratory that focuses on the study of soft matter, polymers and bio-inspired materials — materials with properties like those found in nature. For example, she is designing materials inspired by strong spider silk and by the flexible jaws of sea worms. She is the principal investigator of PIRE: Bio-Inspired Materials and Systems, a five-year, $5.5 million grant from the National Science Foundation.

Doctoral student Chase Thompson (left) is mentored by Prof. LaShanda Korley.

In a photograph taken before the coronavirus pandemic necessitated social distancing, doctoral student Chase Thompson (left) is mentored by Prof. LaShanda Korley.

She is associate director of the new Center for Research in Soft Matter and Polymers (CRISP) at UD and associate editor of the Journal of Applied Physics. She has published 55 peer-reviewed publications, which have garnered 1,342 citations, according to Google Scholar.

Korley is well recognized as a leader in her field and received the 2019 Lloyd N. Ferguson Young Scientist Award for Excellence in Research from the National Organization for the Professional Advancement of Black Chemists and Chemical Engineers (NOBCChE).

Darrin Pochan, Chair of the Department of Materials Science and Engineering, said: “Professor LaShanda Korley’s deep expertise and prolific research in biomimetic, composite materials for a variety of sustainability and biomedical applications make her a well-deserved candidate for Fellowship in the AIMBE. She is an international leader in the development, processing, and understanding of new polymer materials and soft matter that will have an impact on a wide variety of technology in the future. The Departments of Materials Science and Engineering, Chemical and Biomolecular Engineering, College of Engineering, and UD are proud to call Professor Korley a colleague with all looking forward to many future successes in research, mentorship, and more.”

Eric Furst, Chair of the Department of Chemical and Biomolecular Engineering, said: “LaShanda is a tremendous colleague. I admire her scholarship in soft materials that she pursues with her students, often inspired by nature and natural systems, but I also deeply appreciate her dedication and contributions to the service missions of the college and her departments. Her leadership in activities like Future Faculty Workshop and large center initiatives enrich our community and college research neighborhoods.”

Korley joined UD in 2018 from Case Western Reserve University, where she was the Climo Associate Professor in the Department of Macromolecular Science and Engineering. Korley holds a doctoral degree in chemical engineering, with a focus in polymer science and technology, from the Massachusetts Institute of Technology. She received a bachelor’s degree in both chemistry and engineering from Clark Atlanta University as well as a bachelor’s degree in chemical engineering from the Georgia Institute of Technology.

UD has a strong tradition of biological engineering. Other UD faculty members who belong to AIMBE’s College of Fellows include: Thomas Buchanan, Prasad Dhurjati, Dawn Elliott, Jill Higginson, Kristi Kiick, Kelvin Lee, Abraham Lenhoff, David Martin, Terry Papoutsakis and Millie Sullivan.

Photo by Kathy F. Atkinson

Cracking the Code

Cracking the Code

UD researchers explore methods to turn biomass into sunscreens, shoe soles and more

Lignin is a major waste product of the pulp and paper industry that can be converted into chemical building blocks to create other materials. It comes from trees, grasses and other biomass.

Over 70 million tons of lignin is left over annually as a byproduct of pulp and paper manufacturing processes. Biorefineries and paper manufacturers currently burn lignin for heat or discard it in landfills. This inefficient use of a potentially valuable raw material is a massive economic, environmental and societal stressor that needs a renewable solution.

With a $3.69 million grant from the National Science Foundation, University of Delaware’s Thomas H. Epps, III and an interdisciplinary team of experts will unlock new routes to sustainably develop materials from lignin. The funding is part of a broader NSF effort to support research driven by specific and compelling problems, in this case materials life cycle management, which includes everything from how materials are developed and created to how they are disposed of at the end of their useful life. The UD work is among the first cohort of awards in the new Growing Convergence Research initiative — one of NSF’s 10 Big Ideas.

Epps, the Thomas and Kipp Gutshall Professor of Chemical and Biomolecular Engineering at UD, is the project’s principal investigator. He has assembled a team of researchers with expertise in catalysis, polymer chemistry, polymer engineering, environmental toxicity and ecohydrology to tackle this problem.

The research team aims to develop and evaluate comprehensive strategies to convert lignin into more valuable products, such as lubricants, sunscreens and adhesives, or impact-resistant materials, from rubber bands, gaskets and shoe soles to car tires, dashboards or bumpers.

The project leverages UD’s institutional strengths in catalysis, energy and polymeric materials, and it involves faculty from three of UD’s eight colleges: the College of Engineering, the College of Earth, Ocean and Environment and the College of Agriculture and Natural Resources.

Major faculty participants and co-principal investigators (PI) on the project include Dion Vlachos, director of the Delaware Energy Institute and the Catalysis Center for Energy Innovation, and the Allan and Myra Ferguson Professor of Chemical and Biomolecular Engineering; Delphis Levia, professor of ecohydrology and chair of geography; Aditya Kunjapur, assistant professor of chemical and biomolecular engineering; Changqing Wu, associate professor of food toxicology; and LaShanda Korley, Distinguished Associate Professor of Materials Science and Engineering.

Recyclable, friendly materials

One major challenge is that lignin traditionally is the hardest part of the biomass to break down. Additionally, different kinds of biomass (trees, grasses) have different chemistries, which can influence the types of molecules and materials that can be generated from the lignin.

The researchers plan to develop a roadmap that links environmental factors, such as where the biomass comes from and how it grows, to how the end products created from the biomass perform, while also considering the downstream impacts of biomass use.

“One of the big problems that we want to address is sustainability,” said Epps, who also holds a joint appointment in materials science and engineering and directs the Center for Research in Soft Matter and Polymers at UD. “Not just thinking about whether we can make new polymers or catalysts from biomass, but understanding the impact of these polymers on the environment, in terms of toxicity and in terms of the resources.”

An exploratory aspect of the work involves looking at whether these molecules can be broken down into their original components after their useful life is over. Epps explained that when polymer materials are reused, the new material’s properties, such as strength or flexibility, are normally not as robust as the original polymer. A material’s performance typically degrades each time it is reprocessed.

Instead, the UD research team is exploring ways to break materials back into their chemical building blocks so that they can be regenerated in a way that retains the full properties of the original material.

“This regeneration would make things that are infinitely recyclable,” Epps said. “If we could break polymer materials back into their monomer building blocks, we would have a blank slate. We could build the exact same thing or maybe something even better.”

Each member of the research team brings knowledge and experience critical to driving forward sustainable materials development. For example, Vlachos’ extensive expertise in catalysis — processes that accelerate chemical reactions — lends itself nicely to creating the molecules that Epps and others need to make polymer materials. Similarly, Epps’ monomers and polymer designs can help Korley develop polymer networks with specific mechanical properties, like toughness. These skills, Epps said, can help other scientists and engineers turn polymers and other materials into functional items like toy action figures or airplane wings.

Meanwhile, Levia’s hydrology and forest ecology know-how can help the research team explore noninvasive methods to predict the chemistry in trees so that they can design ways to make materials from biomass that are not only better, but also environmentally friendly and nontoxic. Wu can lend a hand here, too, by providing the research team with information about how different structures lead to more or less toxicity in materials, which can inform Kunjapur’s work engineering different enzymes and organisms to make specific molecules.

Six graduate students from across the project’s three collaborating colleges will work as an integrated team to link stem flow chemistry in forests to the structural properties (strength, impact resistance) that the researchers are finding in polymers being developed out of the biomass.

“This interdisciplinary work has potential to drive forward a circular economy that eliminates waste and encourages the continued reuse of resources. UD can be a leader in this area,” said Dion Vlachos, director of the Delaware Energy Institute and a co-PI on the project.

Bundlemers

Bundlemers

New polymer units created by UD, Penn researchers could enable materials breakthroughs

From tires to clothes to shampoo, many ubiquitous products are made with polymers, large chain-like molecules made of smaller subunits called monomers, bonded together. Now, a team of researchers from the University of Delaware and the University of Pennsylvania, with primary support from the U.S. Department of Energy Biomolecular Materials Program, has created a new fundamental unit of polymers that could usher in a new era of materials discovery.

The researchers designed and created rigid, self-assembling, customizable polymer chains by linking together new building blocks called bundlemers — a term coined at UD. They recently described their work in the journal Nature.

[su_youtube url=”https://youtu.be/0bbj9-SQRng”]

To create bundlemers, the team assembles four individual peptides, themselves short chains of amino acids, into nanoscopic cylinders. The bundlemer cylinders are then linked together, end-to-end, through a highly efficient and controlled series of chemical reactions known as “click” chemistry. The resulting polymer chains are rigid, rod-like molecules that are based in biology yet do not exist in nature. Bundlemer chains can then be modified with components such as synthetic polymers or inorganic nanoparticles to create new hybrid nanomaterials.

“There’s a basic premise in materials that if you can control function and structure, then you can essentially build anything,” said Chris Kloxin, study author and assistant professor of materials science and engineering and chemical and biomolecular engineering at UD. “We have a very well-defined structural unit, this bundlemer, upon which we have the ability to add chemical functionality at any location.”

Because of their rigidity and customizability, bundlemers could be used to design new materials with a wide range of applications, from high-performance fibers to single-use plastics to biologics, medicines that employ biological components instead of traditional chemistries. Biopharmaceutical research and development is a growing area of expertise at UD, home to the National Institute of Innovation in Biopharmaceutical Manufacturing (NIIMBL).

The rigidity of bundlemers could also make these materials useful as substitutes for famously strong materials such as the steel in bridges, the silk in parachutes or the Kevlar in bulletproof vests.

Practically every day, co-author Darrin Pochan, chair of the Department of Materials Science and Engineering at UD, and Kloxin come up with a new application to pursue — enough to keep them and their students busy for years.

The researchers designed and created rigid, self-assembling, customizable polymer chains by linking together new building blocks called bundlemers — a term coined at UD.

The researchers designed and created rigid, self-assembling, customizable polymer chains by linking together new building blocks called bundlemers — a term coined at UD.

“Our idea is that these bundlemers truly are building blocks in every sense of the word,” said Pochan. “We are going to build many, many materials and technologies out of these building blocks.”

The team has applied for one patent and plans to file more.

The origin of bundlemers

Pochan and co-author Jeffery Saven, professor of chemistry at Penn, have collaborated since 2012, when they received a National Science Foundation DMREF grant to study designer materials. Kristi Kiick, Blue and Gold Distinguished Professor of Materials Science and Engineering, was also a collaborator on that project.

Saven’s computational chemistry group designs and models specific peptide sequences to identify promising candidates for synthesis and characterization. “Our group is involved in designing and identifying what to make, then modelling these systems to try to understand their stability,” Saven said about his group’s role in the collaboration.

Saven collaborates on new molecule designs with Pochan and now Kloxin, who joined the collaboration later, where they discuss the pros and cons of different peptide sequences and how to best create a new material with a specific property. Then, at UD, Pochan and Kloxin make the materials.

“It’s good to have feedback on important features to include in the calculations,” said Saven about the importance of iterative discussions between groups at UD and Penn.

Said Pochan: “We computationally design and then experimentally create the molecules to do the assembly into the bundlemer building blocks. We are not limited to nature’s toolbox.”

Still, despite careful planning, the initial experimental results surprised Pochan and Kloxin — in a good way. When they first saw measurements of the bundlemer chain stiffness, they assumed that something was wrong. Usually polymer chains are loose and flexible like spaghetti, but polymers created from bundlemers are more like long, thin, sturdy rods.

“The rigidity was quite surprising and stunning,” said Pochan. It wasn’t a mistake. Additional testing revealed that bundlemers have a much higher stiffness by weight than almost any other polymers, such as synthetic polymers and DNA.

After synthesizing bundlemers, the research team characterized the materials using transmission electron microscopy and cryogenic transmission electron microscopy in the Keck Center for Advanced Microscopy and Microanalysis. They also confirmed the size and structure of the bundlemers through small-angle neutron scattering experiments at the National Institute of Standards and Technology’s Center for Neutron Research, which has a cooperative agreement with UD for the Center for Neutron Science.

Chris Kloxin and Darrin Pochan in the lab.

“These are tools for anybody to use, whether you’re a chemist, engineer, or physicist,” said Darrin Pochan (right), chair of the Department of Materials Science and Engineering at UD. “It’s hard to think of an equivalent material or experimental tool people use widely. It’s like a toolbox for anybody to design future things.”

Jeff Caplan, confocal microscopy expert and director of BioImaging at the Delaware Biotechnology Institute, performed Stochastic Optical Reconstruction Microscopy (STORM) Imaging to visualize tiny segments within the bundlemers. Caplan is a co-author on the Nature paper.

This project wouldn’t have been possible without the complementary expertise of the principal investigators. Saven excels in computations and theory. Kloxin excels in polymer chemistry. Pochan excels in materials synthesis and characterization.

“We have plenty of overlap with our expertise, but the point is that without one of us, none of this would have happened,” said Pochan. “Without facilities, such as UD’s Keck Microscopy Lab, the BioImaging Center at the Delaware Biotechnology Institute, and our relationship with NIST and the Center for Neutron Research, this kind of work would not happen.”

The future of bundlemers

Next, the team aims to make bundlemers more accessible, easier to synthesize, and scalable.

Scientists around the world could use bundlemers to address a wide variety of grand challenges in engineering.

“These are tools for anybody to use, whether you’re a chemist, engineer, or physicist,” said Pochan. “It’s hard to think of an equivalent material or experimental tool people use widely. It’s like a toolbox for anybody to design future things.”