Materials innovator Padma Gopalan: Bringing nature’s complexity to polymer synthesis

Posted on 27. Sep, 2013 by in Academic Departments, Annual Report, Features, Issues, Materials Science and Engineering, People, Research

Padma Gopalan

Padma Gopalan. Photo: David Nevala.

Associate professor, materials science and engineering
Director, Nanoscale Science and Engineering Center

Padma Gopalan’s research focuses on designing, synthesizing and characterizing new types of polymers with the ability to self-assemble into a wide range of useful nanostructures. Yet one of her favorite nanostructures comes not from the lab but from nature, on the wings of a blue Morpho butterfly.

Seeing a blue Morpho, one would assume its deep-blue wing color is the result of pigmentation. In fact, the wings contain complex, tree-shaped nanostructures of silica that reflect light and wavelength to create the perfect blue color.

Those elegant wings are self-assembled nanostructures in their purest form.

“It’s a never-ending quest for synthetic chemists like me to see how much of that type of nature we can mimic in the synthetic world,” says Gopalan, an associate professor of materials science and engineering. “The complexity is at a whole different level in nature compared to the synthetic systems we make.”

Gopalan’s research team works on synthesizing self-assembled nanostructures in polymeric materials anywhere in scale from 100-plus nanometers to sub-10 nanometers. These incredibly precise structures have applications in microelectronics, photonics, energy and bioengineering, but the key to their usefulness is control and replication across a larger scale.

“What we are looking for are the underlying rules of self-assembly,” Gopalan says. “How does the chemical structure influence the self-assembly, and how does the self-assembly influence the morphology and the macroscopic properties?”

Part of the fascination of Gopalan’s work is in the materials themselves, which are classes of block copolymers. These are comprised of chemical tandems that act like oil and water connected together, and the resulting thermodynamic factors govern the self-assembly process. “The information for self-assembly is already encoded in the chemical structure of the polymers we make,” she says.

That’s where the polymer design aspect comes into play in Gopalan’s lab. Can they mix in the right components, in the right portions, so that they self-assemble to produce valuable electronic, optical or magnetic properties? Gopalan has a number of patents through the Wisconsin Alumni Research Foundation, including a few that have recently been licensed by the semiconductor industry.

Gopalan joined UW-Madison 10 years ago, as a part of the functional organics cluster hire. She frequently collaborates with scientists across the spectrum, from physics and chemistry to, more recently, biomedical engineering. One current project is looking at how nanostructures help direct the differentiation of stem cells.

“That crossover from chemistry all the way to medicine is truly exciting for me,” she says. “We are able to bring in traditional materials science surface characterization tools and very precise quantification tools that biologists don’t use right now. We create new materials platforms as templates to study stem cell behavior, but bring in tools to build a fundamental understanding of cause and effect.”

Gopalan is trained as a chemist, but her choice of materials science allows her to delve into many different scientific worlds. She has dozens of collaborations in her work with the Materials Research Science and Engineering Center (MRSEC) and the Nanoscale Science and Engineering Center (NSEC), which she currently directs. “There are no hard walls, there are no hard boundaries, and that’s what I love about what I do here,” she says.

The Materials Genome Initiative has the potential to be transformative, both nationally and at UW-Madison, Gopalan says—in much the way NSEC and MRSEC have changed the
research culture of the campus. “The initiative will bring in computational modeling and theorists to work hand in hand with experimentalists like myself,” she says. “Much of the theory has lagged behind the experimental side, in terms of narrowing down the experimental parameters and creating a more predictive role.”

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