The Department of Materials Science and Engineering welcomes Charles Schroeder, Ray and Beverly Mentzer Professor
Schroeder has been an affiliate faculty in MatSE since 2016 and will join our department as Professor of Materials Science in the Fall of 2020. He will hold a joint (25%) appointment with Chemical and Biomolecular Engineering.
Charles M. Schroeder’s research aims to understand the physical and chemical properties of soft materials using single molecule techniques. In recent years, his group has pioneered new methods to precisely interrogate single molecules to understand materials properties ranging from non-equilibrium dynamics to charge transport. A major focus lies in understanding how molecular scale properties give rise to macroscopic behavior in soft materials, including mechanical, electronic, or optical properties. He is an established leader in the field of single polymer dynamics and molecular rheology. At Illinois, his group has extended the field of single polymer dynamics to architecturally complex polymers such as branched chains and ring polymers. In a second area, his group studies charge transport at the molecular level in conjugated polymers relevant to organic electronics and redox-active materials used in flow batteries.
Schroeder is the Ray and Beverly Mentzer Professor in Chemical and Biomolecular Engineering and was promoted to full Professor in 2017. He retains his appointment in the Department of Chemical and Biomolecular Engineering, and he holds affiliations with several other departments on campus, including Chemistry, Bioengineering, and the Center for Biophysics and Quantitative Biology. Schroeder is the Co-Leader of the Molecular Science and Engineering Research Theme in the Beckman Institute for Advanced Science and Technology. He is also an affiliate at the Illinois Materials Research Laboratory and a member of the Biosystems design group at the Carl R. Woese Institute for Genomic Biology.
Schroeder’s research also extends into the areas of colloids and ‘squishy’ particles. In 2016, Schroeder’s group developed the Stokes Trap, which is a fundamentally new way to manipulate tiny particles or single molecules using just fluid flow. His group is using this new method to understand the process of vesicle adhesion and fusion, which will provide fundamentally new insights into a broad class of materials used in personal care products. In a different area of research, his group works at the frontiers of designing and synthesizing hybrid bio-synthetic materials such as electronically active polymers. Recently, his group studied the sol-gel transition and optoelectronic properties of synthetic pi-conjugated oligopeptides, materials that can be ‘programmed’ to assemble into specific shapes with unique electronic properties. In addition, Schroeder is part of a multi-institutional, multi-disciplinary team creating a new class of synthetic sequence-defined polymers that can be used in batteries, energy storage, and sophisticated lightweight electronics.
With his research, he aims to achieve a molecular understanding of functional materials, including their non-equilibrium behavior, which will inform how to process those materials.
Schroeder Research Group
A native of New Jersey, Schroeder gravitated to engineering and the sciences at an early age. His father was an electrical engineer who worked at Bell Labs and during the company’s open houses, he would visit the lab where his father drew fiber optic cables from a three-story-high furnace. In high school, he excelled in chemistry, and as a freshman at Carnegie Mellon University, he decided to major in chemical engineering.
At Carnegie Mellon, Schroeder received a rigorous undergraduate education, which he credits for establishing a strong fundamental basis that has helped move him forward in his career. As an undergraduate researcher, he worked on experimental projects related to colloidal suspension stability and computational modeling of film spreading with mentors Bob Tilton and Myung Jhon. He spent two summers of his undergraduate years at an internship at Intel in Portland, Oregon, working in a microchip fabrication facility. The experience helped solidify his decision to pursue fundamental research in the engineering sciences.
For his graduate education, he enrolled at Stanford University. As a graduate student, Schroeder knew that he wanted to work in soft materials and polymer dynamics, and several faculty members at Stanford were active in those areas. He joined up with Eric Shaqfeh, an expert in theory and computation of complex materials and soft materials. At the time, Shaqfeh had recently begun collaborating with physicist Steve Chu, who was conducting some of the first single molecule studies of polymer dynamics and biological processes.
“I couldn’t have asked for a better set of mentors. They were demanding and had high expectations. They were a superb set of mentors, both scientifically and in supporting my development as a young scientist,” he said.
At Stanford, Schroeder built his experience in conducting simulations and experiments. Back then, and still today, he was drawn slightly more to the experimental side of things, in imaging and microscopy. As his years as a graduate student wrapped up, Schroeder knew he wanted to expand his knowledge in biochemistry and biomolecular materials and, at the same time continue working in fluorescence microscopy and imaging. For his postdoc, he worked in the lab of Sunney Xie at in the Department of Chemistry and Chemical Biology at Harvard University. Xie ran a single molecule lab focused on biophysics and advanced imaging methods.
“That experience expanded my scientific horizons and my skillset. In addition to thinking about the physical aspects of materials, I became intrigued in the chemical and biological aspects of materials, how to synthesize them, and how to study them,” he said.
As a postdoc, Schroeder studied the fundamental process of DNA replication. Following his postdoc, and upon starting at Illinois, his research again became more materials-focused, including hybrid materials inspired by biology. That’s where his research program is situated today.
Understanding Materials at the Single Molecule Level
In recent years, Schroeder’s research has gone in the direction of sequence-defined polymers and single molecule charge transport. Broadly, Schroeder is interested in combining elements from biology, chemistry, and physics to understand how design and characterize new materials.
In one area of research, his group aims to understand the mechanisms of charge transport in single molecules. Understanding charge transport through sequence-defined oligomers and polymers is a crucial step for designing new materials for energy storage and organic electronic devices. For these studies, his group uses custom in-house scanning tunneling microscope-break junction (STM-BJ) instruments to directly measure molecular conductance in synthetic organic materials and biomaterials such as DNA, RNA, and peptides.
Recently, his group has extended these experiments to electrochemical measurements at the molecular scale, such as charge transport in redox-active molecules as a function of the charge state. Broadly, this work will reveal the fundamental science behind charge transport mechanisms in materials used for energy storage and energy capture. This project was initially funded by the Department of Defense’s Multidisciplinary University Research Initiatives (MURI) with collaborators at Northwestern University at the University of Texas at Austin. The MURI team also includes Professor Jeffrey Moore from Illinois, which has resulted in a highly productive collaboration with the Schroeder group to synthesize and study sequence-defined polymers.
“Imagine a long polymer chain where we control at every site the chemical identity of each monomer. If this is possible, then we can directly determine how the charge transport properties depend on the monomer sequence.” A major result from this collaborative project was published in the Journal of the American Chemical Society in 2020.
“It’s interesting to think about charge transport in a single molecule to begin with, but then to also think about how you can control that by changing sequences is fascinating. This is an example of applying single molecule tools to characterize and ultimately design new materials for molecular electronics,” Schroeder said.
Recently, these investigations have focused on redox-active materials used in redox-flow batteries. Here, Schroeder’s group is developing new single molecule electrochemical techniques to characterize charge transport in ‘redoxmers’, which are redox-active small molecules or polymers. This work is funded by the U. S. Department of Energy (DOE) through the Joint Center for Energy Storage Research (JCESR).
Cryo-electron microscopy image of pi-conjugated oligopeptide gels (quaterthiophene-peptide) formed via concentration-driven self-assembly.
In a related area, his lab studies hybrid peptide polymers, which are conjugates between natural peptides and synthetic polymers that are good at transporting charge. His group is studying the self-assembly properties of these materials and aims to understand how the assembled supramolecular structures facilitate charge transport. In recent work, his lab is extending these ideas to nucleic acid conjugated materials and redox-active materials.
“At the same time, we’ve also been taking one of our main tools, which is direct imaging of single molecules using fluorescence microscopy, and applying that to more complex materials systems, such as branched polymers, ring polymers, and concentrated or entangled solutions.” Entangled polymer solutions generally exhibit complex topological chain crossings, not too different than a bowl of cooked spaghetti. Understanding dynamics in these systems at the molecular level is a grand challenge in the field.
One of the newer developments to come out of his lab is the Stokes Trap, a fundamentally new way to trap and “micromanipulate” multiple particles in a free solution using just fluid flow.
Manipulating a single colloidal particle using the Stokes trap. A small particle (2 micron) is moved along a complex parametric trajectory (nearly 1 mm long) in only 9 seconds. Images show snapshots of the particle at various instants of time, with the green line showing the past history. PHYSICAL REVIEW FLUIDS 4, 114203 (2019).
“Unlike optical trapping or electrical trapping, the Stokes trap doesn’t require external force fields such as electric fields or optical fields. It only uses gentle fluid flow to confine and manipulate particles. We’re using it now to look at interactions between soft materials like vesicles, capsules, or polymersomes, for example studying the process of vesicle collision and adhesion. Our work tends to be focused on these fundamental questions, but these are materials that are used in a wide array of applications ranging from personal care products to detergents and liquid fabric softeners,” he said.
Looking ahead to new projects, Schroeder is excited about combining elements of biopolymers with synthetic polymers to look at the additive or new properties that arise.
Schroeder’s research program is centered at the Beckman Institute for Advanced Science and Technology, where he is Co-Leader of the Molecular Science and Engineering Theme. This highly interdisciplinary research theme is focused on several strategic areas and combines faculty and researchers in theory-driven computational molecular science and experiments. For example, this group is rapidly moving into the area of automated chemical synthesis and combined efforts in high-throughput electrochemical characterization of materials. Broadly, this cross-disciplinary team aims to develop new synthetic pathways for new materials and medicines and to characterize the behavior of matter far away from equilibrium. The group also includes ChBE faculty members Charles Sing and Ying Diao, MatSE faculty Chris Evans, Ken Schweizer, Dallas Trinkle, and Qian Chen, and MechSE faculty Randy Ewoldt.
“This is a great opportunity for experimentalists to work with computational scientists in the area of molecular materials, combining new advances in automated synthesis with data-driven design and understanding of new pathways and molecules,” Schroeder said.
Since establishing his research program at Illinois, Schroeder has trained graduate students from the Departments of Chemical and Biomolecular Engineering, Materials Science and Engineering, Chemistry, Mechanical Engineering, and Biophysics. Ph.D. alumni from his group have obtained positions in academia, including faculty positions at Stanford University, Rice University, Duquesne University, and the University of California-Santa Barbara, and industry (such as Intel, Google, and Boston Consulting Group). Schroeder has had numerous undergraduates work in his lab—over 30 undergraduates, including several who have gone on to top-ranked PhD programs.
“We are excited to have Charles join the Materials Science faculty – he will be a leading figure in promoting soft materials research across the Grainger College of Engineering,” said Professor Nancy Sottos, department head and Swanlund Chair.
(A version of this story originally appeared in the 2017 Winter edition of ChBE's Mass Transfer magazine.)