Answering “Why?”

Everyone knows a kid who constantly asks, “Why?” “Why is the sky blue?” “Why do people have teeth?” “Why are hurricanes given names?” According to Benjamin McDonald, he was that kid. “I kept asking ‘Why?’ to the point of exasperation on the part of my parents,” he says. Because McDonald always wanted to get to the root of things, each answer was met with another “why” question. “I saw science as a clear mechanism for trying to answer some of those questions,” he explains.

Currently, McDonald is a postdoc and the self-described “regular old organic chemist learning new tricks and new questions” in Professor Tim Swager’s lab. The Swager lab uses concepts from basic chemistry to create new applications such as materials that react to different chemicals. This has led McDonald to flip the question from “Why?” to “Why not?” He’s still interested in why substances behave as they do, but he has also begun tinkering with these substances. Specifically, he’s modifying polymers to give them new applications.

The language of chemistry

For as long as McDonald can remember, he always knew he wanted to be a chemist. He took a short detour during his first year at the University of North Carolina at Asheville after a disappointing general chemistry class. “I was like ‘I’m going to be a biologist,’” McDonald remembers. He hedged his bets, choosing to double major in biology and chemistry. “And then I took organic chemistry my sophomore year and something just clicked,” McDonald says.

Organic chemistry introduced McDonald to what he calls the hieroglyphic language of molecules. The two-dimensional sketch of a molecule is the hieroglyphic, and reading it allows you to picture the molecule in three dimensions in your head. “We can then understand some of the properties of the molecule, such as the collagen in your skin, based on its structure and how that relates to how our body works and even how the universe works.” He dropped biology, graduating with a bachelor's degree in chemistry in 2012.

For McDonald, organic chemistry offered the perfect level of detail to understand questions like how different types of life processes work — without getting tied down by big-picture complexities such as appearance, behavior, and systematic taxonomy. “I was addicted to it,” he says. McDonald got involved with organic chemistry research, moving systematically from undergraduate research to a doctoral program at Northwestern University.

“My PhD was in total synthesis and reaction development,” McDonald says. This is a field that harkens back to the 1960s, explains McDonald, when the magic-bullet concept developed by Nobel laureate Paul Ehrlich was in full force. Ehrlich believed that molecules could be developed to specifically target a germ while leaving the rest of the body unscathed. “Total synthesis is the art and science of making these small organic molecules, and reaction development is figuring out how to make a specific chemical bond,” McDonald says.

“I was trained in that, which a lot of times sets you up to be a chemist in a pharmaceutical company, which wasn’t that appealing,” McDonald says. Becoming a postdoc in the Swager lab allowed him to find an application for that training outside of the focused approach of the pharmaceuticals industry, he says. “Tim [Swager] is particularly unique because he knows a lot of organic chemistry, but he also knows polymer chemistry, material science, even some electrical engineering,” says McDonald. “As he says, he knows enough about many things to be dangerous.”

Swager, the John D. MacArthur Professor of Chemistry, also makes sure his lab members represent a number of scientific fields. “I strive to bring in a mix of all different types of people,” he says. To this mix, McDonald brings the pure synthetic chemistry. “It takes a lot of skill to make complicated molecules, do multi-step reactions, and to do these fast,” Swager explains. The molecules McDonald is synthesizing require dozens of steps in a row and the yield goes down with each step added. “You need really good chemistry to get any material out, and Ben brings that skill.”

Coming to Swager’s lab was, according to McDonald, a paradigm shift: “to go from being exquisitely focused on one specific space, to seeing someone who is able to use it simply as a tool towards more interesting applications.”

These applications are wide-ranging, from responsive polymers on the surface of materials that can create uniforms that protect against chemical warfare to polymers that can act as functional surfactants, changing the surface tension of droplets in an emulsion. McDonald is one of the polymer chemists in the lab, but these projects are collaborative, involving work with chemists with other specialties, as well as engineers. “Our group is very interdisciplinary, and that is also great training for modern science,” he says. “No one has the one skill set to rule them all.”

Bringing in voices

The same way no scientist can master every skill set, no single person can represent every perspective or human experience, which is why McDonald is concerned with increasing representation in chemistry. “For me, diversity in research is necessary to keep fresh ideas and questions in science,” says McDonald. And when it comes to technological progress, diversity guarantees that as many of society’s stakeholders are involved in the process. “This is important for an equitable society, but also for an  informed and engaged one.”

During his PhD, McDonald was involved in a number of initiatives focused on diversity and inclusion, particularly through the graduate-student-led NU BonD (Northwestern University’s Building on Diversity). “It’s still going on, and it’s an effort to make chemistry more reflective of the general population and bring in more voices.” NU BondD organized workshops, seminar series, and monthly social events that promoted diversity and focused on how microaggressions and implicit bias can impact scientific research.

At MIT, McDonald has focused his efforts on the question of “How?” — How do people get to MIT? “I noticed that a lot of people at MIT always do summer research rotations here,” he says, which allows future graduate students to start building connections at MIT while still in college. “If we want to make the community more balanced, an obvious answer is to have programs that get people who are not the majority in the door,” he adds.

Last year, Swager nominated McDonald for the MLK Visiting Professors and Scholars Program, which enhances and recognizes the contributions of scholars in the community, and in October 2019 McDonald was announced as one of the six MLK Visiting Scholars for 2019-20. “Ben is an outstanding scholar and he’s doing a lot for diversity at MIT,” says Swager.

Recently, McDonald has started talking with the MIT Chemistry Alliance for Diversity and Inclusion (CADI) to create a program that gets more underrepresented groups in the summer research rotations. Similar programs exist in other departments at MIT; the MIT Summer Research Program, for instance, brings underrepresented minorities and underserved students to MIT for nine weeks of research on campus in fields including biology and brain and cognitive science. “I think this is the simplest way to affect bottom-up change,” says McDonald.