How Chromatography Helps Build Better Catalysts

Chemistry doesn't end when the reaction is finished. In many research labs, chromatography is what allows scientists to understand whether their chemistry actually worked.

In this episode of Concentrating on Chromatography, we sit down with Dr. Madalyn Radlauer, Associate Professor of Chemistry at San José State University, to discuss how her research group combines polymer chemistry, catalysis, and chromatography to answer fundamental questions about catalyst design and reproducibility.

We explore how polymer microenvironments influence catalyst performance, why star polymers have become an exciting research area, and how techniques like TLC, silica gel chromatography, gel permeation chromatography (GPC/SEC), and emerging GC-MS methods help guide discoveries in the laboratory.

Dr. Radlauer also discusses mentoring undergraduate researchers, the importance of reproducibility in chemistry, and why chromatography is far more than just a purification step—it's a tool for scientific discovery.

In this episode:

• How polymer-supported catalysts work
• Why catalyst microenvironments matter
• The role of TLC, column chromatography, SEC, and GPC in research
• Developing more reproducible catalytic reactions
• Using chromatography to solve research problems
• Transitioning from purification to GC-MS analysis
• Mentoring undergraduate researchers
• The future of polymer-supported catalysis

Video transcription

Catalysis, polymer chemistry, and chromatography come together in unexpected ways in the research of Madalyn Radlauer, Associate Professor of Chemistry at San José State University. In a recent episode of Concentrating on Chromatography, Radlauer discussed how polymer architectures can create new environments for homogeneous catalysts, why rigorous benchmarking is essential for understanding catalytic performance, and how chromatography—from TLC and SEC/GPC to GC-MS—has become central to answering questions across her laboratory.

Radlauer’s path into chemistry began well before she encountered polymer-supported catalysts. Growing up in New Orleans in a family without a scientific background, she was drawn to science through educational programs, school projects, and an influential high-school chemistry teacher. Her interest in organometallic catalysis developed as an undergraduate at Stanford University, where research with Robert Waymouth introduced her to both catalysis and polymer chemistry. She later continued her training at Caltech and, during postdoctoral work with Marc Hillmyer at the University of Minnesota, expanded her understanding of fundamental polymer science. interview concentrating on chro… interview concentrating on chro…

Today, Radlauer leads a research group at San José State University, a primarily undergraduate institution where mentoring students is an integral part of the laboratory’s work. Her group draws students from chemistry and biochemistry as well as biology, forensic science, chemical and materials engineering, and biomedical engineering—an interdisciplinary mix that brings different perspectives to the same scientific problems. interview concentrating on chro… interview concentrating on chro…

Using polymers to control the catalytic microenvironment

One of the central questions in Radlauer’s group is whether a synthetic polymer can do more than simply support a catalyst.

Traditional homogeneous catalysis often involves a relatively small catalyst molecule dissolved in the same phase as the reactants and products. In that environment, the catalyst can interact freely with solvent, reagents, products, and other components of the reaction mixture. Radlauer’s group is exploring whether placing a metal center inside a structured polymer can alter those interactions and create a more controlled microenvironment around the catalytic site. interview concentrating on chro… interview concentrating on chro…

The inspiration is partly biological. Enzymes demonstrate how a larger molecular scaffold can control access to a small active site, influencing both reactivity and selectivity. Synthetic polymers are far less precisely defined than proteins, but their structures can still be manipulated to influence what reaches a catalyst and under what conditions.

Among the architectures explored by Radlauer’s group are single-chain nanoparticles and star polymers. A flexible polymer chain normally adopts a disordered, collapsed structure in solution. If different points along that chain are cross-linked, it can be locked into a single compact particle. Incorporating a metal-binding site inside such a structure creates the possibility of positioning a catalyst within a polymer-defined local environment. interview concentrating on chro…

The same concept can be applied to star polymers, which consist of multiple polymer arms connected through a central core. By positioning ligand precursors and ultimately metal complexes within this core, the polymer architecture may help isolate or protect the catalytic center from components outside the particle.

Why synthetic polymers are not enzymes

The analogy with enzymes is useful, but Radlauer emphasizes a fundamental difference: synthetic polymers are inherently heterogeneous.

Most conventional polymerization reactions do not produce chains with exactly the same number of repeating units. Instead, the resulting material contains a distribution of molecular masses, expressed through polymer dispersity. Biological proteins, by comparison, are typically produced with a defined amino-acid sequence and molecular mass. interview concentrating on chro…

This creates both a challenge and an opportunity. Synthetic polymers are comparatively straightforward to prepare and modify in substantial quantities, allowing researchers to rapidly vary structures and generate new materials. But those materials are not molecularly identical, making it essential to distinguish effects arising from polymer architecture from effects caused by other experimental variables.

That need has pushed benchmarking from a routine control into one of the central scientific themes of Radlauer’s research. Before evaluating a polymer-supported or otherwise modified catalyst, the group first examines a well-established small-molecule catalyst under comparable conditions. Doing so helps determine whether observed changes genuinely arise from the new polymer environment rather than differences in laboratory procedures, reagents, equipment, or other uncontrolled variables. interview concentrating on chro…

Star polymers: pursuing an approach the literature warned against

The development of star polymers in Radlauer’s group provides a striking example of how research can evolve when an apparently straightforward approach proves much more difficult than expected.

The group wanted to prepare arm-first star polymers, first synthesizing linear polymer chains and subsequently joining them through cross-linking reactions to form the central core. Controlled radical polymerizations had previously been used for this purpose, especially nitroxide-mediated polymerization (NMP) and atom-transfer radical polymerization (ATRP). Radlauer, however, wanted to use reversible addition–fragmentation chain-transfer polymerization (RAFT) because of its tolerance toward a broader range of functional groups that could later serve as ligand precursors for metal complexes. interview concentrating on chro… interview concentrating on chro…

That functional-group tolerance was particularly attractive for incorporating phosphines, amines, amides, and other potential metal-binding motifs. These functionalities can be problematic for some alternative polymerization strategies.

But RAFT synthesis of arm-first star polymers based on styrenic monomers proved considerably more difficult than expected.

Initial GPC measurements with a refractive-index detector showed an earlier-eluting peak consistent with formation of a larger cross-linked material. Because larger macromolecules generally elute earlier in size-exclusion chromatography, the data initially appeared to confirm successful star formation. interview concentrating on chro…

The picture changed when the laboratory gained access to light-scattering detection.

The new detector revealed that some of the apparently successful products contained only around five polymer chains joined together—far fewer than the tens of arms Radlauer envisioned for a star structure capable of effectively shielding its core. This additional information showed that the refractive-index data alone had not provided enough information to understand the actual polymer architecture. interview concentrating on chro…

By systematically revisiting the reaction parameters, the group ultimately developed conditions capable of producing star polymers from several different monomer classes, including styrenic, acrylate, and acrylamide monomers. Combining refractive-index and light-scattering detection became essential for characterizing what they had actually synthesized. interview concentrating on chro…

Only later did Radlauer encounter a paper that effectively warned against using RAFT for the particular styrenic arm-first star-polymer chemistry her group had been attempting. Rather than rendering the work futile, the difficulty became part of the scientific question itself: why does a method work readily for one monomer class but struggle with another? interview concentrating on chro…

Benchmarking the details that experiments often hide

The star-polymer project reinforced another lesson: apparently small differences between laboratories can have substantial consequences.

Humidity, light exposure, laboratory environment, operating procedures, and even the history of a chromatographic column can influence experimental results. Radlauer argues that repeating benchmark experiments is therefore not merely unoriginal repetition. It is a way to establish whether a new result genuinely reflects the variable the researcher intended to change. interview concentrating on chro…

That philosophy is increasingly central to her group’s work. Benchmarking provides a reference point that makes new catalytic results easier to interpret and easier for other laboratories to reproduce.

Chromatography throughout the synthetic laboratory

Although Radlauer describes her group primarily as a synthesis laboratory, chromatography appears throughout its workflow.

Thin-layer chromatography (TLC) is routinely used to monitor reactions, including synthesis of ligand precursors used to prepare metal-based catalysts. TLC also helps determine conditions for subsequent preparative purification. interview concentrating on chro…

For preparative separations, the group increasingly uses dry-column vacuum chromatography. Compared with conventional silica-gel column chromatography, Radlauer has found the method can reduce solvent consumption, silica use, and purification time while still effectively separating reaction mixtures. interview concentrating on chro…

But the chromatographic technique most deeply embedded in the laboratory’s polymer research is gel permeation chromatography (GPC), a form of size-exclusion chromatography (SEC).

The group combines refractive-index, UV, and light-scattering detection. RI and UV signals provide concentration-related information, whereas light scattering responds strongly to molecular size and enables access to absolute molar mass information. interview concentrating on chro…

This distinction matters enormously for structured polymers.

Conventional SEC calibration provides a relative molecular-size estimate based on how a polymer behaves compared with reference standards. Polymer conformation, however, depends on interactions with the mobile phase. A polymer that collapses tightly in a poor solvent can appear smaller than expected, even when it is technically soluble. Radlauer gives the example of poly(N-isopropylacrylamide), which behaves very differently depending on whether it is analyzed in THF, DMF, or water. interview concentrating on chro…

For cross-linked star polymers, this becomes especially important because their hydrodynamic dimensions change when chains are tied together. Light scattering provided the group with an independent estimate of absolute molar mass and, from that, a way to estimate the number of polymer arms within each star—information that could not be obtained reliably from relative RI-based calibration alone. interview concentrating on chro…

Replacing dozens of purification columns with GC-MS

Another current project brings chromatography directly into the group’s work on olefin metathesis.

Radlauer’s team is interested in establishing a standardized way to compare different catalysts for olefin cross-metathesis. A large number of ruthenium catalysts and reaction conditions have been developed, but comparisons across studies are difficult because new catalysts are often evaluated under different reaction conditions or for different substrates. interview concentrating on chro… interview concentrating on chro…

Previous landmark work classifying olefins according to their metathesis behavior relied on performing reactions, purifying products by column chromatography, and determining isolated yields. Repeating that workflow across dozens of substrates and catalysts requires a substantial investment of time, solvent, and labor. interview concentrating on chro…

Radlauer’s group is therefore developing a GC-MS-based benchmarking workflow in which separation and characterization occur during the same analysis.

Rather than isolating every individual product before characterization by NMR, a reaction aliquot could be cleaned up rapidly, combined with an internal standard, and injected directly into the GC-MS system. The group is currently working through practical questions such as response factors and selection of appropriate internal standards for the range of olefins being investigated. interview concentrating on chro…

The goal is a low-touch method that could eventually be transferred between laboratories. A researcher developing a new catalyst could run the same benchmark reaction, use established response factors and an agreed internal standard, and directly compare its performance with existing catalysts.

The approach could also make time-course experiments substantially easier. Rather than performing separate reactions followed by purification at every time point, several aliquots could be taken from a single reaction and analyzed by GC-MS. interview concentrating on chro…

Research as a training ground for independent scientists

For Radlauer, building a research group at San José State University was closely connected to her interest in undergraduate education.

She deliberately sought an environment where she could remain actively involved in the laboratory and help students connect classroom knowledge with current research. Her view of successful scientific training is deliberately broad: students may continue into PhD programs, industry, medicine, pharmacy, or other careers. What matters is that research gives them the opportunity to begin seeing themselves as independent scientists capable of defining and solving their own problems. interview concentrating on chro…

That philosophy is reflected in a group that has at times included more than 20 researchers and students from several different scientific disciplines.

Keep asking questions

Radlauer closes the interview with advice that connects almost every part of her research: keep asking questions.

Scientific progress does not always begin with an obviously novel or sophisticated problem. Sometimes it begins with a result that looks strange, a reaction that changes color in air, a literature result that does not reproduce as expected, or a question that seems so obvious that a student assumes someone must already have answered it.

Her group has encountered precisely these situations. In one project involving spontaneous oxidation, a seemingly simple observation led them to discover that a question they assumed had already been investigated directly had not actually been addressed in the way they expected. interview concentrating on chro…

The lesson extends beyond chemistry. A useful scientific question is not invalid simply because it appears basic. What matters is asking it genuinely, testing it carefully, and repeatedly returning to the fundamental question behind an experiment: What are we actually trying to find out, and what evidence will answer that question? interview concentrating on chro…

Radlauer’s research illustrates how that mindset can connect seemingly different areas of chemistry. Polymer architecture becomes a tool for designing catalytic environments. Chromatography becomes much more than a final analytical step—it becomes a means of understanding materials, benchmarking reactions, challenging assumptions, and building experiments that others can reproduce. And unexpected results, rather than being obstacles, become opportunities to ask the next question.

This text has been automatically transcribed from a video presentation using AI technology. It may contain inaccuracies and is not guaranteed to be 100% correct.

Concentrating on Chromatography Podcast

Dive into the frontiers of chromatography, mass spectrometry, and sample preparation with host David Oliva. Each episode features candid conversations with leading researchers, industry innovators, and passionate scientists who are shaping the future of analytical chemistry. From decoding PFAS detection challenges to exploring the latest in AI-assisted liquid chromatography, this show uncovers practical workflows, sustainability breakthroughs, and the real-world impact of separation science. Whether you’re a chromatographer, lab professional, or researcher you'll discover inspiring content!

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