Paula Hammond

Zierler:

OK, this is David Zierler, Oral Historian for the American Institute of Physics. It is December 16, 2020. I am delighted to be here with Dr. Paula Hammond. Paula, it's so nice to see you. Thank you for joining me today.

Hammond:

Thank you. I'm excited to talk with you today.

Zierler:

All right. So, to start, would you please tell me your titles and institutional affiliations? And you'll notice that I pluralize both because I know you have many.

Hammond:

Well, I am the David H. Koch Chair of Engineering at the Department of Chemical Engineering. I am the Department Head of Chemical Engineering at MIT. And I am a member of the Koch Institute for Integrative Cancer Research.

Zierler:

Have you met David Koch? Have you interacted with him at all?

Hammond:

Oh, yeah. There's multiple ways in which that has happened, in fact. MIT's Chemical Engineering Department has three Koch alum. So, the father of David Koch and two of the Koch brothers got chemical engineering degrees from MIT. So, before I even became a part of the Cancer Institute, David Koch was involved with giving to the practice school and some of the other educational components of the department. And I would say that later on, when the Koch Institute was formed, I met him in that context as well. So, I met him in the context of a faculty member in the department, he as a visiting alum, for example, and then, later, as a new member of the Koch Institute. And then, multiple times after that.

Zierler:

Now, are you the inaugural holder of the Koch Chair?

Hammond:

I am one of five inaugural holders of five Koch Chairs. And the others include Phil Sharp, the Nobel Laureate. Bob Langer, who's the incredible chemical engineer and inventor. And Michael Yaffe, myself, and the fifth one is evading me right now.

Zierler:

So, it was a class of endowed chairs that all came together at the same time.

Hammond:

Yes, they were a bundle, basically, that all came at the same time.

Zierler:

Paula, the Koch brothers, of course, are well-known in the energy sector. But I'm curious, in what ways are they supportive of the kind of research that you and your colleagues at MIT are doing?

Hammond:

Yes, actually, it's quite different in that the funds that went to MIT are dedicated to integration of engineering and biology to solve problems in cancer.

Zierler:

I'd like to ask a very current question right now, and that is, with remote work and the pandemic, in what ways do you have to have a physical presence at MIT, and in what ways are you able to manage things from your home or wherever else to be socially distant?

Hammond:

Ah, yes. Well, one of the things that is fortunate about the role that I have is that I can do just about everything remotely myself. So, I have two primary jobs. One of them is as a principal investigator of my research lab, and an educator of the graduate students in that lab, etc. And the other is as Department Head for the Chemical Engineering Department. And both of those can be done remotely. Now, it does become harder to actually pull together people to talk about ideas rapidly. It definitely helps when you're on the same floor, and you can bring people together in an instant. But it definitely has been possible with tools like Zoom to bring people together in Zoom formats and to have conversations. So, it does require more planning. And there's less of the spontaneity.

On the PI side, one of the things that I feel I've benefitted from at MIT is that at non-pandemic times, you are able to walk through the hallways and see your colleagues, and sometimes meet new colleagues that way. And I have actually had interactions that were unplanned and led to spontaneous conversations, which led to further discussions, and bringing students in post-docs together, and new projects and collaborations. So, that's something that's in the lifeblood of MIT, is this whole notion that people can come together from different fields who are really bright, really smart, and when they do, they can mix, they can intermingle, and especially when you have a diverse group of people, you get a huge and broad set of opportunities for new things to happen. So, that's something that I really love about MIT. It's harder to do that now.

Zierler:

Yeah, and what you're saying touches on something deeper, and that is that doing science is fundamentally a human and social endeavor. It requires that interaction.

Hammond:

Absolutely. It is incredibly human, it is incredibly social. Half of the things that happen, happen because people want to work together. It's actually interesting. There are collaborations that happen because two investigators know that they have relevant science, but they also would love the opportunity to engage with each other on the scientific level and have more of those incredible conversations. And so, that leads to, "Hey, we should write a proposal on X." "You think we can use A to do B?" You end up doing those things, just as you would with friends who get together and decide to start a business, or decide to launch a project together.

Zierler:

To get an idea of how your lab operates, I'm intrigued by the idea that you're able to do so much of it remotely. How much of that is about having colleagues, or post-docs, or graduate students who have a physical presence, and how much of it simply is computers and automated data analysis allow you to watch experiments and understand the data remotely?

Hammond:

For my own research lab, it is largely because the post-docs and the graduate students are present. So, I will typically go in once or twice a week and just do a walkthrough, make sure that the lab safety protocols are still in place, that benches look right, that students look spaced, and just do the kind of responsible PI walkthrough. And I have a lab manager who does that in alternation with me. But otherwise, the students and post-docs are doing the work. And that's something that is true for most of the investigators on campus. Typically, when we get started with our lab, we have just one or two students, and we're showing them how to do things. So, we're in the lab, showing them. But once you get your lab launched, and you have more members of the lab, engaged in the actual experiments, the better they get at the experiments, the better you get at articulating the science, and discussing the science, and innovating alongside them. And so, those roles change very rapidly.

Zierler:

To get an idea of all of your many responsibilities and how you handle them from a time management perspective, in the way that you're dual-hatted or even tri-hatted, do you sort of split your time up 30/30/30 within a given day? Do you tend to work in blocks of time in terms of days or weeks, wearing one hat and not the other? What's your general work style with all of the research and administrative responsibilities?

Hammond:

That's a great question. So, I keep a to-do list that's actually this written pad. It's a little easier if I write it out because I can modify it so easily. And now, I draw a line across the middle of it and put the Department Head things at the top and the research things at the bottom. Not because that's the priority, but because typically, with the Department Head things, there's a hotter deadline. So, I have to sort through those. And then, I try to make sure that during the week, I'm checking things off of both lists.

When we were on campus, I would spend Tuesdays and Thursdays in my research laboratory office. So, I have an office in the Koch Institute. I love that office. It's sort of me, my personality, it's got a lot of color, all that stuff. And it's the same floor as my students. I share it with two cancer biologists, actually, in a suite, and we have a shared admin. So, typically I would go Tuesdays and Thursdays there and sort of spend my day there as much as we could. On Tuesdays, we have our group meeting. And then, when I have meetings that I need to cluster, I try and cluster them a little bit more on those two days for research. And then, Monday, Wednesday, and Friday were days I spent at headquarters. So, I had a geographic way of spacing things that, on the days that I'm in my Koch office, people in the department had to look for me, and the other way around when I was in the headquarters. So, that helped. Now, everything's a smudge. But I do try to get all the things checked off as much as I can.

Zierler:

Paula, let's take it all the way back to the beginning. I'd like to hear a little bit about your family background, starting with your parents. Where are they from?

Hammond:

So, my father is from Greenville, South Carolina. And he was actually the first in his family to get a college degree. And he has an interesting story because he grew up in a typical African-American family in Greenville, at that time, a very segregated town, of course. And then, he ran into a group of priests who ran a kind of mentoring and tutoring center, and that led him to go to college. That greatly shaped where he went. So, from there, he went to school at Xavier University, and then ended up at Wayne State University in Detroit. Dad is a biochemist PhD. He got his PhD at Wayne State. He was one of the first African Americans to gain–these are early days, so there weren't a lot. And he became the director of health laboratories for the city of Detroit. So, during my growing up period, that's what his job was.

Zierler:

I want to ask a very specific question, because this is something that I'm fascinated by, and I've learned a lot about this. Did your father ever talk about, when he was in school as a boy, even in high school, having teachers who were overqualified that, because of segregation, they didn't have opportunities to be college professors? And so, you had these brilliant people whose only job that was available to them was teaching a biology or chemistry class in high school. Did you ever hear stories like that?

Hammond:

I have heard stories like that. I haven't asked my father, though it would be easy for me to do that. That is a great question. Actually, I think that the best thing I can think of is that my father went to a high school in Greenville, South Carolina that was famous for how excellent the teaching was, but it was all Black. And a huge number of leaders, including Jesse Jackson, came out of that high school. Which I'll remember the name of later, of course. I just visited Greenville just before COVID hit. Like, the second week of March. And I toured the place. There's a statue for the high school. I would imagine that high school was full of highly, highly qualified African-American teachers. It actually got raided and partially burned down by a supremacist group sometime after my father's graduation. And they pieced it back together, but never completely. But yeah, I think that that is the typical case, that you have these very, very bright people who are teaching high school. And my father was a beneficiary of that.

Zierler:

Is your mom from South Carolina as well?

Hammond:

No. So, my mother was born in Claremore, Oklahoma. And she was essentially the daughter of a Baptist minister and his wife, both of whom passed away maybe four years apart from each other. And so, when my mother was 12, she moved into her aunt's home, which was in Little Rock, Arkansas. So, she had her high school growing up period in Little Rock. And she remembers stuff like Little Rock Nine and all those things. And the earliest home was in Claremore, Oklahoma, which is the home of either Roy or Will Rogers. I'd have to check that. One of the Rogers.

Zierler:

Maybe both.

Hammond:

Maybe both, exactly. They have a museum for him, I know that. So, she was from sort of the southwest South. And she moved to Detroit when members of her family moved to Detroit. But before that, she actually got her master's at Howard University. So, she got a bachelor's in nursing and then a master's in nursing from Howard. And then, she went back to Detroit, where by that time, a large amount of the Little Rock-ians had moved for auto jobs. And she started working at one of the hospitals. But ultimately, she ended up becoming the inaugural Dean of Nursing for the Wayne County Community College. Wayne County is Detroit's county. And Wayne County Community College is actually a really large community college in the center of downtown Detroit. So, she was unusual in that she helped found the nursing school and ran it.

And this would be in the middle-70s. So, Detroit was experiencing a period in which African Americans were becoming the dominant group in Detroit. It was after the riots in '68. And the NAACP was very strong there. My father was heavily involved in the NAACP. African Americans of every class were sort of thriving in Detroit at that time. But Wayne County Community College, mom was the only Black dean as I'm aware, and certainly was a woman dean. So, she was heavily involved in education as well as nursing. And I got to see her put on a power suit every morning. Because she used my closet for her closet. And she had those 70s power suits, and she'd come in and pick out the tweed one. The bow with a blouse and all the rest of that, and the hills. And she'd go out, and she'd power into her job.

Zierler:

And where did your parents meet?

Hammond:

A friend matched them up. So, they met on a blind date. A friend who knew this PhD who's really smart, and mom who's really smart, and she's got a master's degree, sort of put them together. And that's how they met essentially.

Zierler:

And for you growing up, science, and medicine, and education, that was the family business.

Hammond:

It really was. That was really a major theme: public health, science, and education. And growing up, we were told we could do anything in the world. And education was really stressed. So, I love school. I loved every subject. And I have an older brother and a younger brother, but we're only about two to two and a half years apart, so we're pretty close. And until high school, I was interested in being a children's fiction writer essentially. I was definitely going to be a writer, and I was writing stories, and putting them in contests, and all the rest of this kind of thing. And when I got to high school–I should mention that Detroit did have what may still be an existing sort of challenge with a number of its public schools. So, we went to Catholic schools, and that was what a lot of people did at that time. You could go to Catholic school, it wouldn't be extremely costly, and you could still get a strong education. And my father was Catholic because of the experience he had.

I went to Catholic school in my neighborhood growing up. But then, I started going to Academy of the Sacred Heart in Bloomfield Hill. So, I grew up in Detroit proper on the northwest side. Academy of the Sacred Heart is in Bloomfield Hills, which is a kind of posh-y setting. It was a wonderful all-girls school. It was small, there were 40 students in my class. And it was there that I was able to have a chemistry class that actually had a lab. And that was my first time actually doing chemistry lab was my junior year. And I'd been doing well in physics and math, etc., etc., etc. So, when I started doing chemistry, I got really excited. I was sort of mixing chemicals and watching colors change, generating heat, seeing matter transform. It was exciting. So, I would hang around for longer and help clean up. And the teacher was a woman. She was the only woman science teacher I'd had. So, her name was Mrs. Herr, which there's some irony there. But it's that classic German spelling, H-E-R-R. And she told me that I should really think about chemical engineering. And I asked her about it, and she said, "Well, you're strong in physics and math, so you would handle the engineering very well. And you love chemistry. And the world needs more chemical engineers. We need more engineers in general." So, I looked into it, and I decided to investigate. And that's how I ended up choosing chemical engineering.

Zierler:

Now, did your parents involve you and your brothers in their careers? In other words, growing up, did you know what it was like to be a biochemist or to be in academic administration and nursing? Were these things that were sort of tangible to you?

Hammond:

I think so. We didn't do a lot of go-to-work day. That was before they had the whole bring your kid to work type of thing. I knew what my mother's job was like in part because I would hear her talking about it. And I knew that a lot of that involved tangles with other members of the administration at times and discussion of curriculum, but also, huge pride in ceremonies like the pinning and the capping of the nurses, which she would share with me. And I was at a couple of those ceremonies, watching her confer these pins or caps. And we talked about it, and she said that these women's lives were being transformed by the obtaining of this degree, which allowed them to go out into the world and serve others, but also allowed them to make a very nice living. So, that was very meaningful. And my father was very interested in getting us involved in science. So, he would buy Christmas gifts like Build-a-Brain, or a heart with blood that you can pump through the plastic veins, and these kinds of things. We had a chemistry set. We had a few other things. But my father didn't talk a lot, so he didn't talk a lot about his job. It wasn't until I asked him as an adult about his job that I learned a little bit more about the fact that he was responsible for things like the water quality, and testing of all of the public facilities, and those kinds of things.

Zierler:

Growing up, did you have a sense of the very difficult racial injustices in Detroit? Was that a part of your reality? Or was your parents' social standing and education such that that was something that was a bit more removed for you?

Hammond:

It was not removed. It was definitely in front. As I mentioned, both my parents were actually very politically aware and active. And I hope I get this right because this is from my childhood memory, but I believe for a period of time, my father was one of the presidents of the NAACP Detroit chapter. Either that, or he was heavily involved. But he actually had meetings in our living room for some period when I was small. I remember we would go down the stair and look at who was in the living room. And they'd be meeting and talking about things. And he was very active in NAACP all the way through his mid to late age. So, by the time I was in high school, he was running the NAACP's Act-So Program, which is a program that is like an Olympics for Black youth. And I would say that he was also a Democratic delegate. I have memories of, at a small age, going through our neighborhood with the rubber band and the flyer and just putting them on doors. So, I remember that. It wasn't a lot, but it was enough.

So, I was aware of politics. I remember the TV would be on, and my parents were fairly open with commentary about the news. So, I remember comments about Nixon, and about the war, and definitely about Civil Rights issues. I was so small when Martin Luther King got shot that I don't have a very direct memory of it. But I remember the sadness that followed it. And I remember the impact on the community. And that was during the time when my neighborhood was going from mostly white to mostly Black. My parents told us many times that when they bought the house we grew up in, it was, like, 1961, and my mother was pregnant with my brother, who was going to be born in '62. And they looked at the house a few times. The first time they looked at the house, they were told something about how it wasn't available. And my mother said she could see people peeking at them when they stopped at the house and so forth, the neighbors and so forth. So, there was actually a campaign on that block to try to block them from buying the house. And this is common. This was happening all over.

So, they ended up being the first Black family in that part of the neighborhood. And eventually, people moved out, and there was a change, over time, in our neighborhood. But they definitely told me about it. My mother said she remembers standing pregnant with my father, waiting for the real estate agent to come. And cars went by, but nobody stopped. So, apparently they got stood up the first time they tried to see the house. And the second time, they were told it wasn't available. And so, a third time, they were able to get in. Growing up, we heard a lot about what their lives were like, and we saw a lot about what was going on. Detroit was changing in the way that I was describing. It was becoming a city with a Black mayor and Black elected officials over time. And I was observing that and observing the sense of power gained that the community was feeling. And it was very real.

Zierler:

And professionally, I'm sure your parents experienced, whether they talked about it or not, either overt racism or what today we might call microaggressions, right?

Hammond:

Yes.

Zierler:

Like, maybe people assuming that your mom was a secretary, or that your father was a janitor, or any of that kind of stuff. My question for you is, would they bring those terrible moments home as teachable moments for their children? As they emphasized education, did they want to give you a clear-eyed sense of the kinds of things that you might experience in your own successful future?

Hammond:

What I remember is, and I'm going back now to think about it, there's always an awareness that we needed to be better than anyone else to make it in this world. And they were very open about that, that, "You have to achieve on a higher level because you're Black. Because people will make assumptions about you, people will judge you, they will assume you don't know anything, they will assume you aren't capable. So, you need to project your best self all the time." So, we heard that message multiple times. And when things happened that seemed a little bit askew, there was always a discussion about, "This could be a factor." And typically, they would be things that are subtle, but, "Why did the teacher imply that you should do A instead of B?" These kinds of things. And we would have conversations about that. So, they were very open about the fact that the world is not going to treat you the same. It's simply not. And you're going to have to run ahead of the crowd and show them what you can do. And don't listen to what they think you can do. So, that was really solid messaging that they brought home all the time.

Zierler:

And what might they have taught you about channeling certain inevitable emotions like anger, or despair, or frustration when these were things that inevitably you would have to deal with?

Hammond:

My parents would come home and talk to each other about their frustrations. And I knew that a lot of this had to do with what they were experiencing, which were these aggressions or pressures at work. My mother trying to maintain her authority. My father doing the same as director of Health Laboratories. And I would hear them say, my father more frankly than my mother, "This is racist." I would hear them talking to each other, right? So, we knew that was there.

And we knew that it was OK to express it amongst each other. But we also knew that there was huge effectiveness in being able to present your case and slam it in place with class. So, the whole idea is, to express your anger can be effective if you are able to articulate it, sharpen words with reason, and then aim it. So, that was sort of the kind of thing that we talked about was just being effective and getting those points across. But we were never told to hide our anger. I think the whole idea was more around being able to channel it in a way that you can actually get your point out there. And it's hard to do that if there's noise and fury. So, you do have to take a step back to be cool, right?

Zierler:

As you tell it, in high school, as you were coming into your own as a budding chemist, obviously, there's no way to know what would've been otherwise. But in what ways was being in an all-girls environment important? Or did it supercharge your initial academic interests?

Hammond:

I think that was important because it allowed me to feel a sense of ownership around science and math in a way that might've been a little different had I not been in an all-girls environment. Because I think in that all-girls environment, you felt like the playground is level, right? The playing ground is level. And you can essentially run out there and speak without being sort of self-conscious about what you're saying. You can ask questions without having something in your head that is telling you, "You're probably wrong." A lot of those barriers go away.

And especially at that time, but I think in these times, too, there's a tendency to think, "The boy over here's probably got the right answer, so I probably won't raise my hand on this one." Or, "I put myself out there, and I'll look foolish in front of my peers, and that's not worth the risk." But in an all-girls environment, a lot of those risks get swept aside, and you just go for it. And you feel that the math that you're studying is entirely yours, the science that you're studying is entirely yours to own. There's not a sense that there's someone else who has somehow the greater access or greater ability or facility in that. And that helps you shake the image or the false sort of perception that, "This boy is better than me because he has to be. He's a guy. He's got to know the math better than me," right?

Zierler:

Who was it that instilled in you a sense of confidence that applying to a place like MIT was within range?

Hammond:

Ah, that's a good question. I think it was a combination of my parents and my teachers. I'd always gotten really good grades. Even to the point I was teased about it in elementary school. But I loved school, I loved problems, and I skipped a grade in 6th grade and still felt really comfortable with the material. So, I was around people who were always telling me I was smart. And especially my parents. They told all three of us, "You're smart. You can do anything. Go for it."

So, I didn't think there were barriers. Certainly did not think that there were barriers to getting into places. I knew that they were challenges, and I really want to get into them. But when I applied to universities, I applied to MIT, Cornell, Columbia. I didn't apply to any California schools because that seemed further away somehow. But yeah, I applied to these top schools, and I was like, "OK, I want to get into a place where I get challenged." I really wanted to be challenged and to go for the top. And all of the textbooks that I was reading would have citations about MIT, or, "So-And-So at MIT discovered something or another." I thought, "Well, this is one of the top places to be. So, I've got to go for it and see if I can get it."

Zierler:

MIT was the most attractive one for you, of course.

Hammond:

It was. When I got into these schools, I did do a visit tour. I went to Cornell, I think I went to Columbia, I visited a couple of other places. And, of course, University of Michigan. But when I visited MIT, it was totally different. It was as if I walked into this world where all of my people were. All of these people were talking about things that fascinated them. They got all excited about science, they got geeked up about getting into a lab and doing experiments. I loved the fact that they were into gadgets and devices for fun. It felt like I was at home. I spent most of my time in elementary and high school well-treated by my teachers, and I had some good friends, but to a large extent, treated as a little bit weird by my peers. Just a little different, reading all the time, kind of quiet, really into math. I was sometimes respected, sometimes not with a sense of otherness on that level for me. So, coming to MIT was like, "Oh, no, everybody is like me." It felt great.

Zierler:

You mean intellectually, of course. But as an African-American woman, you were probably very much in the minority in two regards.

Hammond:

Absolutely. Yes. It was 17% women the year that I entered. And I think that there might have been 35 or 40 African-American students out of the 1,000 the year that I entered. And that was considered a good, healthy size for that time. So, it was small on both sides. So, everyone was like me, was more about, "Everyone else is kind of a little bit geeky, other, into the science." However, the diversity was definitely low. Most of the students were white males, with some Asian males, and then some women. And then, that little population that I described of African Americans, and there was a small population of Hispanic students. So, in terms of going into the classroom, I felt intimidated. I did. And maybe it was great that I had that affirming experience at Sacred Heart. For the first time, entering a classroom and thinking, "Well, these other people must know the answer." I think I'd had the experience of having conversations with people and understanding they had more math than me and maybe been exposed to more computing and things of that nature.

And some of them had the unfortunate tendency to share things like SAT scores and all of this, so I'm feeling very intimidated already. And I learned later that there were many students who tended to just sort of exaggerate their abilities. Maybe that's the way some people dealt with their insecurities. But they say, "Ah, that was an easy test." "Ah, that's easy. This is easy stuff." So, you're sitting there trying to read, and learn, and grasp aspects of calculus that you haven't had before, and the people around you are giving the impression of, "I've got this stuff down," and you're just going, "Oh, my God. Am I the only one who's, like, drowning here, just trying to keep up?" And when it comes to answering questions in class, for that freshman year, I just said, "Let me just catch my breath, and hang in the background here, and see if I can just keep up."

After the first semester, I felt much better. I thought, "Oh, you know what? I survived. I survived the first semester. And I did stuff, and it worked. And I was able to pass these classes." Fortunately, MIT is pass/no record, at that time, for the entire freshman year. So, that helped a lot. But that experience did a few things for me. I learned that I could do it, even when it was really challenging. That was important. I learned that I can find friends who can help me because the other Black students did get to know each other, and we did form a network, and we did help each other out. And there's a Black Student Union tutorial session that I would go to. And so, I really became engaged with the Black student community. And we were really supporting each other. Without that, it would not be possible. I will say, if I were totally isolated and did not have that network, it would've been a very different experience for me. And from that, I learned that it's OK to poke my head out and push myself forward a little bit. So, in the next semester, I started to raise my hand again, I started to take little risks. I just needed to have a sense of foundation, of support first.

Zierler:

And was it chemical engineering from the beginning? Or you were sort of open to a wide variety of majors to possibly pursue?

Hammond:

I came in [to study] chemical engineering. That was it, after those experiences in high school. And so, I signed right up for that. But at MIT, you choose your major at the end of your freshman year. So, I had time to think about it, and we all took the same classes and what we call the General Institute Requirements. And freshman year, it's stuff like Physics 1 and 2, Chemistry 1, Calculus 1 and 2 basically. And then, your humanities classes.

Zierler:

Were there any professors in the Chemical Engineering Department who became mentors to you at all?

Hammond:

Yes. As I became more engaged in the material, I found that I really wanted to get close to the part of the field where I could actually connect molecules together. And that, for me, became polymer science. Making large molecules out of small units, small ones. And generating all these materials that have different properties. So, because I loved my chemistry class, I was looking for where I could have more of that. Those classes were taught by the chemical engineering faculty.

So, there were two faculty members, Professor Ed Merrill and Professor Bob Cohen, who taught polymer classes. And this was in my junior and my senior year. And those were really incredible, meaningful classes for me. I thought, "OK, this is cool stuff. I like it." And I would talk to them afterward. To the extent that they remembered me afterward and became mentors for me later in life as well. But yeah, those were two faculty members that really stood out as having an impact early on. I thought, "This is really exciting stuff." Ed Merrill in particular had a way of teaching, because he was an English and drama major as an undergrad, as well as chemistry – he had a flair. He had all of these Gilbert and Sullivan references to the effects of polymer chemistry. Yeah. So, he pulled you in.

Zierler:

In the world I usually live in, in physics, of course, there's this key divide between theory and experimentation. I wonder, in chemical engineering, as an undergraduate, if you sensed that there was a theoretical side to it, an experimental side, and where you sort of fell on one or the other.

Hammond:

In chemical engineering, there's a computational side, which is theory-based. People are using computation to simulate things like fluid flow, and heat and mass transfer across boundaries. Because chemical engineering is all about engineering processes. And that is hugely engaging sort of the physical chemistry of systems and the mechanics and fluid dynamics of those systems at the same time. And transposing them, of course, with a beautiful set of differential equations, right? So, the computational folks will focus more on how we can better replicate what we see and use that as a predictive mode. Or, how we can use that to uncover phenomena in fluid flow and reactive systems.

And so, I would say, for example, right now in our department, there are, I believe I'm correct in saying, 11 out of 35 of our faculty, roughly a third of our faculty, are heavily computational. Then, the experimental side is everything else. It's essentially looking at how we can actually implement experiments to build systems that are driven to do or achieve a set of applications. And because it is an engineering field, typically, the experimental work can be looking for fundamental phenomena and sometimes is, but is more frequently directed toward the design of a final system, or product, or device that achieves something. Like a battery with high efficiency, as an example, or a drug delivery device.

Zierler:

Were there any summer internships or semester laboratory experiences that were most formative in you figuring out what you were good at, what came natural to you?

Hammond:

As an undergraduate, I had a couple summer experiences. The more memorable one was at Dow Chemical Company in Midland, Michigan just before my senior year, just after junior. And there, I actually was working with research engineers who were looking at the structure property relationships in high-impact plastic. This high-impact plastic is used as the resin miner in refrigerators. So, it has kind of a temperature range that applies to it for impact resistance. And we looked at how changing the three different monomers that are used to make the polymer changed those characteristics. So, I actually ran the reactor. It was a mini-reactor. Very nice, because by changing the pumps, how much of each of these monomers is introduced – it's actually a little bit more complex than I'm describing because it was a rubbery material that then had a hard shell. It was actually a particulate material that then got melded together. And so, you had soft and rubbery, you had kind of glassy tough properties, and you were balancing those to softness, versus hardness, versus brittleness. And you're looking at temperature resistance to low temperature.

So, I actually did experimental design. That was my first experience with designing an experiment so that you get the most out of the numbers of experiments that you're doing to find trends. And I did the trend-finding, and I think I got excited about the fact that I was able to both create the materials, and understand what the trends were and how to design a system that had a specific set of properties that I was looking for. And I took that back, and I think I used it later in my graduate work as well as just in general. I think that was really important because I got to see the application end of things as well.

Then, in terms of undergrad research in labs, as a UROP, what MIT calls Undergraduate Research Opportunity Program, or UROP, which is what the undergrad researchers are called, and I worked in Charlie Cooney's lab on a bio-separations reactor. And that was fun. I didn't end up choosing that part of chemical engineering to work in, but I had to some of my own design of glass, where I remember going to the glass shop, and requesting this separations setup, and determining the parameters of that. So, I think it gave me a sense of ownership of research.

Zierler:

It sounds like even as an undergraduate, you had a very healthy balance between doing basic science just because it was fun and really being motivated by applications and societal value.

Hammond:

Absolutely. Absolutely. I think that the basic science sort of drives the curiosity and, "What's going to happen if I change this, or change that? And can we understand what this molecule or what this system is doing, and how it responds?" But then, you start thinking, "If we can do that, then what if we...?" And that leads to the invention and the ability to then translate that into something that performs a task that you want or has a function that you need.

Zierler:

Did you ever think that you would go into industry, given the fact that chemical engineering is such an industry-specific and job-friendly kind of path from an undergraduate perspective?

Hammond:

I did. In fact, when I was approaching the end of my senior year, I had thought about grad school, and I had thought about working. And I actually worked for a couple years before going to grad school. And this was also a set of complex decisions. I was engaged at that time to my first husband. For reference, I later remarried. And my late husband passed away a few years ago, but that was really the marriage that was for most of my life. But I was engaged at that time to another African-American engineer the same year, mechanical engineer. And because of my path, I was maybe a bit young. I was 20 at the time of graduation and wasn't sure if I wanted to go into grad school right away or if I wanted to do it at all. I was still thinking about it. I was still intrigued by polymers, but also had gone through a pretty intense bachelor's degree program. So, we decided to take jobs in Fort Lauderdale, Florida. And I was a process engineer at Motorola. So, that was my first job.

Zierler:

What was the motivation to go to Georgia for a master's degree?

Hammond:

So, after two years of working in Fort Lauderdale, Florida, I came to realize, "I'm not going to move any further along a path that I want to move along." I was only essentially responsible for a major plant that had high yield, and I could make improvements that were meaningful because they saved money, but they wouldn't really make a huge difference. And so, it was harder to get excited. On top of that, the work environment was not great. This is where a lot of, again, these more explicit race and gender issues were definitely present in my workplace. But primarily, I pushed to get my first promotion, and then decided, "I really want to get into research. And to do that, I need to get a degree."

And at the same time, my then-husband was feeling the same thing and wanted to get an MBA. And he is from Louisiana. So, the South was kind of the region that he had an affinity for. So, a good compromise was to move from Florida to Georgia. He got into Emory to get his business degree, and I applied to Georgia Tech Research Institute so that I could work while he was getting his MBA. But GTRI pays for your master's, so I could also get a master's degree. So, that was how that all sort of came together, in that move to Atlanta. And it was good. I think it worked out.

Zierler:

Was it a terminal master's degree? Could you have stayed on for the PhD? Or it was a self-contained program?

Hammond:

I could've stayed on for the PhD. And that was actually originally the plan. "I'll get the master's. He'll finish his MBA. He'll start working. I'll go full-on into the PhD." And I really did love being back on a campus. Georgia Tech provided me the opportunity to get back into research. I had a great boss, I met a number of great people and formed some good friendships. And I took the qualifying exams and passed the PhD qualifiers to go out of work. I took all the classes required for both the master's and PhD. But I found out that MIT had a new program specifically for students interested in polymer science. And it was called the Program in Polymer Science and Technology, and it was launched by Bob Cohen, one of those two professors that I mentioned earlier. And I wrote him and asked him about it. He had just started it in 1986. And I think I asked him in '87. And I decided to apply for it, just in case I could get back into MIT. And I got accepted into the program.

And as much as I was having fun at Georgia Tech, the chance to go back to MIT was just incredible for me. It's just an incredibly different place. I felt that in getting back to MIT, it's sort of like you go from kind of a monochrome palette to this huge color bouquet. The diversity is different now, but at that time, the diversity was, in terms of where people were coming from, in terms of the nationalities, and backgrounds, and things that people brought from different places was just huge at MIT and in that area. So, I loved the fact that there were people from everywhere. Still need to increase the number of underrepresented minorities. But it is cool to know that you can engage with somebody from Turkey or Singapore, and that you're getting all these different perspectives.

On top of that, the level of excellence everywhere is so high that you feel like you can engage any and everyone. And because of that, there's a kind of leveled high respect for everyone, I think, from the scientific perspective. Everyone listens to everyone. Because you're bringing something to the table. That's why you're here, right? And I love that about MIT. So, the chance to go back was really meaningful for me. So, I went back to MIT after finishing the master's. So, I finished out the master's and then went back.

Zierler:

I wonder in what ways leaving MIT and then returning broadened your horizons and made you appreciate things that you might not have otherwise had you sort of gone straight through from undergraduate.

Hammond:

Yes. I think that's a very good point. If I had just stayed there, I think I wouldn't have been able to grow in the same way. First of all, at my first work experience, I learned how to stand up for myself in a very different way. I actually had to deal with a very broad set of behaviors, and attitudes, and perspectives. I was in a place where a large number of people were trained in different settings, that maybe there are people who just had different levels of enlightenment about things like race, gender, and expectations. And so, I learned how to kind of sharpen my elbows and push my way forward in that way. I also learned, in that first experience, what it was like to be responsible for a huge operation, and what it meant to actually be thinking about that, and to be involved in the maintenance and the well-being of that part of a company. So, that was meaningful. I learned a lot about the workplace in general.

And then, at Georgia Tech, I think I had an opportunity to completely rebuild my confidence because the Motorola experience, though I learned a number of things, was not one that was boosting my confidence because of the environment. It also helped me reengage my joy for academia. And when I got back to Georgia Tech's campus and was able to walk on a campus, get involved in campus interactions, get back in the classroom, I realized that I wanted to be a faculty member. So, that was where I really had that revelation, "This is what I want to do. So, let me figure out what I need to do to be able to actually become a professor." The whole idea that you can develop an idea, and as long as you can find someone to fund it, you can make it real was huge for me. And those were all realizations that I made in going back from work into an academic setting, which was Georgia Tech. And so, that really shaped me in that sense.

Zierler:

How did you develop your relationship with Michael Rubner?

Hammond:

Ah, yes. So, Michael Rubner was, I think, one of the coolest professors in polymer science at that time.

Zierler:

Was he there when you were an undergraduate? Did you know him from then?

Hammond:

No, he actually, if I'm getting my timelines right, may have started when I was graduating. But I wouldn't have known him because he would've been too junior. And he was in materials science, and I was in chemical engineering. But when I came back in the Program for Polymer Science and Technology, you can have an advisor in any of the departments as long as the professor works in polymer science. So, I came back as a chemical engineer, but I could choose from faculty in all of the different departments, any faculty who works in polymers. And when I came back, I was really interested in working on materials systems that had sort of really interesting and cool structure property function. But I talked to a number of faculty members, and what struck me about Michael Rubner was, he was the youngest of these faculty members, he was still a junior faculty member, and he was incredibly high-energy, and engaged, and intense about his work, doing well, but he also had a life. And that struck me as incredibly encouraging. Because I had already decided I was going to be a professor, but, "This is going to be a hard road." I was already thinking about how I would have a family as a married grad student. And I knew that this would be something that might happen during grad school. And I also wanted to find somebody that I could model in terms of how I might be able to work or deal with my own career.

So, when I met with Michael and talked about research, he was totally animated. Just high-level excitement. And he was making materials that underwent these dramatic color shifts when you stretch them and when you applied different fields to them. And he was also designing materials with electronic conducting properties and all the rest of this. So, really excited. But I had a couple of experiences. One was, I think I stopped by his office early one time, and there was music coming out from under it, so I walked away and came back. He was like, "Oh, I think you came by. I was just finishing my flute lesson." And I'm like, "Wow, he has a flute lesson." It was so cool that he would still have something else about him that he fostered. And then, the other time, we were talking about the next time to meet, and he was saying, "I can meet then, but it would have to be a shorter meeting because I have to leave at 4:30. There's traffic, and I need to see my wife every night." I was like, "Oh, wow. I heard that junior faculty live in their offices and in their labs, and don't go home until late." In fact, I encountered junior faculty later in my life who were like, "Oh, yeah, I make it home for the late show." But Mike Rubner, he went home, he saw his wife, he had a life. And he thought of it as very important. So, I thought, "OK. I can do this. If he can do this, then I can do this."

Zierler:

And his style as a mentor, did he essentially hand you a problem to work on for your thesis that was related to his research? Or did he let you come up with something on your own, and that's how your dissertation developed?

Hammond:

It was really a combination of both. So, he started me on this diacetylene containing polymer project where you get these color changes because I was really fascinated with that. And there was a student who was in his lab, who was just graduating, who had just finished establishing these materials as polyurethanes. And the idea was, "The polyurethanes stretch, and they change color. Maybe we can make a high-strength fiber, and that will give us this high-strength fiber that will show how much stress it's undergoing with color change."

So, I started on that project. And for two years, I labored away, learned the chemistry, and was making these nylons, but it was very difficult to make the precursor to the nylons. So, it got very low yields, hard to generate the materials system. So, I made some progress in part of my project, which was a completion of the polyurethane one, but I hadn't moved into the new material. And in the middle of that, I went off and had a baby. And by the time I came back, maybe because I had all of that time to turn things over in my head, but I thought, "You know what? We don't have to make a nylon. Why should it be a nylon?" So, I proposed to Michael, "It's really difficult to make this monomer for the nylon, but I can make great polyesters with this other monomer. It has the same diacetylene in it. And it won't be a high-strength fiber, but it may be a good film-former." So, he said, "Well, go ahead and try it."

So, I made those materials. They actually ended up being liquid crystalline. So, they ordered in a specific way. And they had these very sharp transitions in that order at different temperatures, so they would undergo these sharp color changes at given temperatures. And I therefore had a thermal-chromic materials system. And I was really excited about that. I was able to look at structure property function and determine how to tune these. And it became, for me, a big success for my thesis. So, Michael gave me the room to change the program and take things in a different direction because we certainly didn't propose those materials in any kind of grant. And he also was patient with me when the other stuff would not work. And that's worth a lot, too.

Zierler:

Paula, after you graduated, given that you already had Dow and Motorola under your belt, did you feel like that was all you needed in terms of industrial research? The move to Harvard, was that very much self-consciously staying in academia?

Hammond:

Yes. In fact, I was finishing my PhD. In chemical engineering, it still is a little, but then it was very common that almost everyone would interview as a PhD. So, I interviewed in my last year of my PhD while I was finishing my thesis for faculty positions. And when I received the offer from MIT, the idea was, "OK, you're from MIT. We're hiring you. It would be good if you had experience elsewhere, and a post-doc is good experience anyway. So, why don't you go away and then come back?" So, I took a year and a half away before starting the position. But I was able to start my post-doc knowing that I already had accepted the offer at MIT.

Zierler:

I wonder, maybe it didn't affect you at all, if having that security allowed for greater intellectual adventurism as a postdoc, that you could not feel encumbered by job considerations, and publications, and all the things that you need to do. Did that factor into your postdoc at all?

Hammond:

Absolutely. It gave me sort of a carte blanche in my post-doc. Because I was coming in, and I was also sort of self-funded. I ended up with an NSF post-doctoral fellowship. So, I was coming in already funded and without a need to get a job afterward. So, I used it as an opportunity to think about how I can manipulate surfaces in a way that might help me in my career as I launched as a faculty member. And George Whitesides had just gotten papers out on microcontact printing, which is this method of taking a silicone stamp and inking it with these singular molecules that self-assemble on a surface, so that you have this Angstroms-thick layer of assembled molecules, these alkane thiols that present a certain functional group on gold. And you can pattern the gold. And you can do the same thing with silicon surfaces and other surfaces with the right molecule. So, it was really about printing molecule-thick films and patterns, and the patterns were micron-scale.

So, that was really a big sort of uncovering. The terminology for this area became soft lithography because you could get lithographic-scale features just by stamping this chemistry down. So, I first started looking at electrochemistry on patterned surfaces. And that came from a conversation with George Whitesides. But then, I became really interested in charged polymers, polyelectrolytes. And this was something that was born in part because I had seen talks about polyelectrolyte absorption.

Mike Rubner, my former advisor, had become interested in aspects of layer by layer as well. And I thought, "Maybe I can use this patterning method and layer by layer to direct polyelectrolytes to certain parts of the surface." So, I began working on layering thin films onto these patterned surfaces where one chemical functional group attracts the polymer, and the other one repels it, and then building films of plus and then minus charge on the portion that builds the film. And this is the layer by layer technique, which had just come out. Those papers came out maybe a year or two before I started my post-doc on absorbing positively charged species, just a single monolayer, and rinsing anything that's not fully absorbed, and then, absorbing a single monolayer of the negatively charged species. And as long as the species have two or more charges, you get this overcharged compensation. So, you keep reversing the charge. So, you build these kind of layers on layers on layers. And that creates a stable film.

So, I started with that general idea. And that became a part of my research lab when I started up as a faculty member with the idea that we could understand fundamentally how to control where layers go and use that to assemble things on surfaces. And what that became was, essentially, in my lab, an opportunity to incorporate things into the layers. And that's how we began working on some of the things that I have in my earlier career, which include electrochromic thin films, and conducting thin films, and a range of sort of device-style systems. And then, ultimately looking at batteries, battery electrodes that were assembled, not just of polymers, but carbon nanotubes and nanoparticles. I started working with colleagues like Angela Belcher, incorporating her viruses that can be used as templates for inorganic oxides and a range of other materials that become interesting for these battery and solar applications. And I was working with Yang Shao-Horn, who is an electrochemical engineer, on carbon nanotube electrodes for high-density batteries. So, it became this entire area in my lab, which really helped with my sort of first seven of eight years or so. Maybe more, I would say.

Zierler:

When you got back to MIT, in what ways were you looking to establish, intellectually and academically, new pathways forward? Finally, not as a student, not as a graduate student, not as a post-doc, but as a professor, in terms of the classes you wanted to teach, in terms of the kinds of graduate students that you wanted to take on, what were the most exciting and compelling academic pursuits for you at that time?

Hammond:

All right. At that time, I was very interested in being able to control where different material sets would go on a surface. So, this whole idea of very selective deposition, as I was calling it. And we published a good deal of controlled deposition based on hydrogen bonding, electrostatics, and other methods. I was also very interested in creating functional thin films using this method and being able to advance those functional thin films into devices to create lightweight thin film device systems. So, those were all part of my original vision.

I also had a part of my lab that was looking at liquid crystalline block copolymers. These are polymers that also have self-assembly on different levels, on the level at which the liquid crystal rod-like structure orders itself into layers, and then there's a polymer backbone, to which these rods are connected, that separates and creates sort of a hierarchy of order. And with those systems, the idea was, we might be able to create highly ordered thin films that would give us interesting electro-optical properties, but with the curiosity piece, would also have morphologies that are driven by how the liquid crystal orders. And the question was, "We have two different kinds of ordering going on. What would control that order? Which element would win?" And in that early work, we looked at fundamental questions like that, "How does it order, and why? And what's driving it? And why does it go on the surface, and why?" and whether that's a strong or a weak interaction.

Collaborations, really, are what helped me move these toward application. Because we began working with colleagues who were interested in building devices, be they optical devices, switches, or systems that would go into electrochemical energy systems. But ultimately, I did transition. My outlook at that time was to have an impact there in terms of science. And I believe I did, and we were able to set several examples. But I did shift my focus as I moved on through tenure and began looking at biological systems as well and biomaterials. So, in terms of research, those were the original questions. And you find in your academic life that you keep changing, and adjusting, and getting interested in different kinds of problems. And so, that portfolio changes. And then, you asked about grad students and so forth. Do you mean along the lines of grad education?

Zierler:

Yes, but let me first ask about your budding interest in the biological side of things. To come back to this divide or the dual interest in the basic science and the applications, of course, in the realm of biology, there can be such a powerful human and poignant dimension to the research that you can really contribute to not just basic science, but really fundamental breakthroughs and discoveries that can really help people. So, I wonder if, as you were maturing as a person, as a professor, as a scholar, as an intellectual, if the immediacy of applying your skills and experience to real-world health applications was sort of part of the mix of motivations for you.

Hammond:

Absolutely. Even when I was just starting as a faculty member, I would go to conferences that were broad. And I would step out of the electro-optical or electrochemical symposia and go to the biomedical one to see, "What are people doing?" I was just very curious. I think even as a graduate student, I had thought about these two paths that interested me, and I was very curious about the path I hadn't followed, which was the biomedical one. Because there's a chance to generate something that is going to have a final impact on a life.

And there's something just simply compelling about working with biology in general, having a living cell respond to a materials system that you've designed introduces a dynamic that is really compelling, that you might be able to direct or change cellular behavior, or direct or change, on a larger scale, networks of cells, so that you end up addressing, healing, treating people. And that was really fascinating to me. So, even before tenure, it was rolling around in the back of my head. And I took a sabbatical after tenure. During that sabbatical, I started pulling out some of these questions and looking at them. I spent time on my sabbatical with colleagues who really helped show me how to think about biology and how to talk biology because there's definitely a language.

Zierler:

On that note, with biology, intellectually and also in terms of your collaborative work style, given that you don't come from a biological background, how much would you rely on the knowledge of your collaborators that did come from a more bio background, and how much of it was you reading stuff on your own? What was the most effective balance that you would strike on these collaborations?

Hammond:

For me, the fastest way to learn was to read a few of the most important papers, usually recommended by a colleague. To go to talks. Going to talks really helps because you're sitting there, and they are telling you the story of how the cell functions. And because, especially if you're going to a broader conference, they're trying to address a somewhat larger audience, you'll get some breakdown of the biological system that they're trying to describe. And you'll get a lot of the sort of key ideas down. If you go to enough of these talks, you begin to see, "A-ha. The key here is we need to activate T-cells. Or the key here is," whatever the challenges are that you hear expressed multiple times. So, you get to hear not only the biology, which is good, it's good to know the biology, but you don't necessarily understand the challenges. But in these talks, you see your biology colleagues talking about, "What we would like to do." Or, "If we could tame this," or, "If we could drive that." And so, that really helps understand, "OK, these are important areas to think about. Is there a materials system that might be able to address that challenge?"

And finally, in learning biology, along with these talks, what's most effective is engaging in collaborations with one of your students being involved directly. Because then my students learn the language. And so, you end up learning it in your engagements with your students. You learn a little, they learn a little. But over time, the nature of grad school is such that the student becomes the expert over the advisors. That's always the case for that student's project. That's student has got his or her nose in it, totally immersed. And as you're talking with them, they give you, like, these corrective phrases as they move along. "Actually, now, it's more like…" You know? You learn a huge amount just from talking with them about the project.

Zierler:

I'll ask a general question, and you can either answer it specifically or broadly, whatever's most meaningful to you. Perhaps, just to take one example, drug delivery. In what ways does a chemical engineer bring sensibilities to these collaborations that make them successful where biologists working only with their own colleagues, within their own fields, might not achieve their objectives? You personally being a chemical engineer, what is that sensibility in academic training that's so vital that you bring to these partnerships?

Hammond:

Oh, that's great. I think I'm very lucky because I am at this institute that brings biologists and engineers together. And so, we think about that a lot. First, with respect to chemical engineering specifically, we learn how to design processes and, essentially, control them. And this means that we can think about whatever biomedical problem we're looking at as a system, and we can consider how to manipulate or perturb that system and how to control what's going in and what's going out. That ends up being extremely useful because that set of tools that we have, understanding how mass changes, how heat changes, how essentially a flow of chemicals may go in and out, even if they are bio macro molecules, understanding how you can control those things is ultimately what chemical engineers spend a lot of time studying and working on.

So, that means that when we begin to look at, for example, a drug delivery problem where we're trying to get a molecule to a tumor or to another part of the body, and we don't want it to have negative interactions. We can think about how we can control the transport of that molecule, whether we can incorporate polymers, and here we have the polymer science piece, that actually undergo a controlled rate of degradation. Or do we create something that is highly responsive to biological environments? In which case, manipulation of pH, or ionic strength, or changes in those, or a gradient in them can cause a change in your carrier.

So, that's sort of a big picture. I think chemical engineers, more broadly, are able to think about how to solve problems from a quantitative perspective. We understand how to assess a complex system, and manipulate that complex system, and understand what happens when you change different aspects of that complex system. And that's something that is important because when we think about cells and how cells interact with each other, how they interact with their surroundings, we're really talking about a large number of complex interactions.

And engineers can help to actually describe how those systems work over time. So, that's a really sort of broad-brush picture, but it is that kind of thinking that we go in with. And we think about that as a perspective that we can use to help solve problems. For my own work and the engagement at the Koch Institute, there's this, I think, huge excitement in being able to bring biological understanding together with the ability to engineer and design specific materials set.

And a great example of that is one of my earlier interactions at the Koch Institute. We have a huge retreat where we all go and present ideas. And one of the biologists, who is a systems biologist in the Koch Institute, was talking about the fact that they had examined this particular kind of resistant tumor cell, which is common, will undergo a kind of compensation when it is drugged with a chemotherapy drug. However, if you administer an inhibitor of a given type to this cell first, and then wait 20 to 24 hours, and then deliver the chemotherapy drug, that inhibitor turns off a series of switches within the cell, and the cell responds to the chemo drug. In our lab, we have been looking at nanoparticles, which are essentially a core with concentric layers of these polyelectrolyte layers around it. And with that, we're capable to have drug in the layers and drug in the core, and we were finding that we could release these in a kind of sequence. So, we got together and talked right after that because we had been talking about staged release. And he had been talking about why staging could make a difference in treating tumor cells. But there's not a very pragmatic way to do that, having a patient go through these stages of chemotherapy and inhibitor treatment. So, we designed a nanoparticle, which actually releases the staged system. And we tested this in an animal model and found that it made a very significant difference in the rate at which the tumor grows, essentially diminishing the tumor size significantly. And so, that's a simpler example.

Zierler:

Let me ask the same exact question, but not going to biology, but going to physics with regard to your work on energy efficiency. In what ways does a chemical engineer bring sensibilities to alternative energies and thinking about moving beyond carbon-based fuel sources that physicists and non-chemical engineers might not have on their own?

Hammond:

Oh, that's great. I think it's the same kind of question in that we think about a system, and when it comes to, for example, battery design, one can imagine that, especially for the range of batteries that have been examined more recently, not only are you concerned about the materials systems that you're using to build the battery, but you're also concerned about the rates and kinetics at which the electrolyte and the charged carriers are moving. Essentially, where they can move to, how much surface area they have to actually undergo these electrochemical reactions. And all of those are actually questions that chemical engineers are trained to work on.

For example, if you just look at a cathode or an anode and consider that you're essentially looking at reaction and diffusion, a chemical engineer can actually determine the sets of equations that describe these complex sets of reaction and diffusion that take place at the interfaces of these electrodes. If you then begin to modify properties of those systems, you can then predict how those will actually modify the efficiency or the capacity of a battery, for example. This goes to a much larger scale, though, for sustainability. And if I sort of put on my Chemical Engineering Department Head had for a minute, we have chemical engineers who are looking at, for example, how we can design everything from redox flow batteries, which rely on the flow of the electrolyte and the carriers at the same time, to get extremely high efficiency at low cost, to catalysis, where you have catalytic systems that are designed to convert some of the simplest compounds, like CO2, and Nitrogen, and air, into meaningful synthetic compounds in a much greener and more sustainable fashion.

We have examples in which we've been able to convert biomass and biofuels, and those are heavily chemical engineering-based problems. They typically are asking the question, "How do we design this process so that we can efficiently and with the lowest energy input possible convert A to B?" Or, "How do we design this molecule from this starting material that is a sustainable starting material, so that we can have a very meaningful fuel? And can we design it so that the end products are the ones that we want?" And, in fact, one of the really interesting chemical engineering processes is CO2 conversion. "Can we actually take excess CO2 and drive it into a different state that is no longer going to be part of the harmful accumulation of CO2 that causes the climate issues that we have?" So, CO2 conversion into solid products that can be actually used, or carbonaceous materials that can actually be put back into the Earth. So, these are questions that are being examined by chemical engineers. CO2 utilization.

Zierler:

And there's so much exciting stuff happening in this realm at MIT generally. In what ways are you collaborating with your colleagues at the MIT Energy Initiative and the energy futures work that they're doing?

Hammond:

Heavily, heavily. So, in our department, I would say about a third of our faculty or more are funded by the MIT Energy Initiative. We have faculty working on photovoltaics and light-emitting diodes, which are very energy-conservative. We're looking at sustainable processes, including one of our faculty members who designs polymers with very highly selective pores, so that we can have membranes that can remove pollutants very effectively and can be implemented into processes that normally require huge amounts of energy for distillation and replace that with membrane filtration, which is a low-energy process. We have faculty who use computation and optimization to determine the best ways to design energy systems, including batteries. And so, there's actually a second center that sort of arose from the presence of MITEI, which is funded by Toyota, for example, that looks at a car battery as the focus for these kinds of approaches. We have another connection, which is the CO2, which I just described is actually a center that is run by one of our faculty members on basically capture of CO2. And the director MITEI itself, the MIT Energy Initiative, is actually a Chemical Engineering faculty member, too. So, I guess you could say we're all over.

Zierler:

Yeah, you have an inside person there.

Hammond:

Yeah, exactly. Exactly. Chemical engineering has really, over the past couple of decades, focused on alternative energy, CO2, and how to lower the impacts of it. Something called process intensification, which is getting more efficient processes that use fewer resources, so that you actually, in the production of anything, have a lower environmental footprint. Right now, there's a huge emphasis on the range of everything from batteries to fuel cells. I'm trying to think of additional ones. I have a short list, but there's lots of sustainable polymers to lower waste. So, we have a faculty member who's looking at how we can design meaningful polymeric materials that would break down more entirely into waste products, and another faculty member who's looking at how we can train microorganisms in a reactor to break down some of the plastic materials that are generated. So, we have it sort of going at both ends. And we have folks working on lignocellulosics, which are probably the most abundant waste material, and how to convert them into meaningful products.

Zierler:

Paula, I'd like to ask a few questions about your career in education, starting at the undergraduate level. What have been the most enjoyable and meaningful classes for you to teach undergraduates at MIT?

Hammond:

I don't teach it anymore, now I'm teaching a class that I like, but my favorite class was when I taught the polymer lab. It takes a lot of effort, but because polymer science is what really got me going, this polymer lab was a favorite. It was taught originally by Ed Merrill, the same person that I met as an undergrad, who only just very recently passed away. And he actually implemented all of these really accessible experiments in the lab. So, students come in, and one of the first things they do is they make these hydrogels, which stretch and expand, and essentially, they learn about the physical chemistry of polymer solutions and polymer gels. There's a rubber band experiment, in which you can experience how stretching a rubber band generates heat. And this is all about, basically, entropic changes that take place. And so, they actually do a series of measurements to try and calculate or quantify some of those effects. It has a lab in which you make a nylon system at an interface, simply by pulling it out. It feels like magic, like you're pulling a never-ending thread from nothing because the reaction's taking place at two interfaces and is continuously generating a nylon.

So, it has these projects in it where students kind of get to have some oohs and ahs. But you also get to talk about the physical chemistry. It's largely a physical chemistry lab with some synthesis. So, you get to talk about the really unique physical chemistry of really large molecules. Why things are rubbery. What does rubbery mean? Why does that property exist, for example, and they get to explore that. What's a hydrogel? Why do you have something that's somewhere between solid and liquid, and why is it so porous to certain kinds of molecules? So, these kinds of questions, they get to ask. And the students love that class, and they get excited, they get geeked up. And they work in teams of three. So, I really enjoy teaching that class.

Now, I'm teaching a class that I enjoy as well, which is the senior design lab. And in that one, we typically take a problem that is based on work that we're doing in our lab, and I worked with one of my students to turn it into a question that the students can answer. And they have some freedom in which part of the question they want to focus on with those systems. And so, that's a fun lab, too. It requires some work to be able to put it together in that fashion, but the students get a lot out of it. We did it the previous year, and one of the students stayed with us in our lab, working on that project, and decided to go to grad school, was not originally intending to, because she loved the research so much.

Zierler:

Paula, I like to joke that with my students, I'm not getting older, they just keep getting younger, right? And this year, our freshmen, many of them are born after September 11, which is just crazy, right?

Hammond:

It is crazy.

Zierler:

So, I want to ask, given this is the generation that truly grew up with computers, not just, like, an Atari or the first generation Mac, but grew up with pretty advanced computing, I want to ask you generally, from your vantage point as department chair, in what ways is this computer fluency allowing them to do things in the chemical engineering curriculum, or grasp things, or accomplish research that might not have been available to you when you were an undergraduate and when computers were, shall we say, at a much more primitive state than they are now?

Hammond:

That's a great question. I think the fact that they can ask almost anything and get near immediate answers is already just a huge transformation. So, when I was getting engaged in chemistry and math, I pretty much relied on whatever material was literally given to me in a physical form. You pored through that, and you tried to make sense of that. If you're going to get any additional resource, you go to the library. And maybe there's a supplementary text that the teacher recommended. But you're not going to be able to get much more than that. Unless you can just grab another student or a tutor who might help you.

But now, especially for the more general topics, you can get a huge amount of background. The internet provides several different levels of tutorials. MIT's courses themselves are available, a large number of them, online, either through the MITX or edX program, or through our older program, which was basically courseware for all. So, you can actually take classes with different voices, different lecturers with different styles, and you might be able to find one that helps you more. Not only that, but you can rewind, play it again, and rewind, and play it again so that a certain concept can get driven in a little bit more. So, those tools can make material more accessible. I think that that is a huge gift.

But I also acknowledge, especially after this year of COVID, that because that's possible, sometimes students experience more stress, in the sense that they feel that they need to watch it again and again. There's a constant decision-making about the time you want to afford to dive deeper into a topic versus accepting your current understanding level and moving forward. So, it's an interesting balance that I didn't have to think about.

Zierler:

On the graduate side of things, it's always a dangerous question, and I don't want you to name names in terms of who your most successful graduate students are and who you've been most proud of, but I guess the best way to frame the question is, looking generally over all of your graduate students, all of your interactions, what are some shared characteristics that your most successful graduate students have had that you can point to and say, "I see what they've all had in common as I've watched their careers blossom from my interactions with them"?

Hammond:

I would definitely say that one of them is persistence. The students who have done well and gone on are ones that have taken the problem in their thesis and their work, and they found a way to find their research story in it. And that often requires persistence because sometimes the first thing that you propose doesn't work. And you can become demolished by that experience of hammering at it and hammering at it, and it still coming out a rock instead of a diamond. Or you can take a look at it from a different angle and go, "OK, well, what can I learn from what I'm doing here? Or do I need to shift to a different rock?" So, I would say persistence and looking at a problem is one of them. And I would say resourcefulness is another. "What is it around me that I can use? Who is it around me that can provide some insight? And how can I then use that insight?" So, I think that those characteristics are definitely present in really successful students.

Finally, I would say optimism is one of the characteristics that stands out, that there's a sense that, "I can do it. It'll work. Something good's coming out of this." And I think it's the optimistic spirit that allows you to survive the rougher patches and to take a step back and still feel a sense of self-appreciation, even when things are going down. Because you need to have that sort of positive sense that in the end, things will come together, that sense of positivity and that, "This is going to work," to get through those difficult times. Those are three. I'm sure there are many others. But I would say it's not necessarily things like outright brilliance or anything like that. I think those kinds of core characteristics that keep you going are ones that, I think, are incredibly important. I would say being able to see opportunity is another. Being able to recognize an opportunity in the experiment that was a mistake or in the finding that's a little bit unexpected, and pursue that, and sort of see where that goes. I think that's also a key characteristic.

Zierler:

Just to bring our conversation up to the present, what are the things that you're working on right now?

Hammond:

So, in the nanoparticle area, we have a newer program, in which we're designing nanoparticles so that they not only can make their way through the blood-brain barrier, which is a part of the big challenge in our field, but also, so that they can selectively target and associate with tumor cells, so that we're able to drug the right cells in the brain. So, this is actually a new project that started right around the same time as COVID actually, in March. It is actually a collaboration with University of Edinburgh, and it's a Cancer Research UK project. So, it's got systems biologists, and it's got engineers. And we're the engineers working on the delivery aspect of the problem, the idea of targeting tumor cells with a combination of drugs that are, based on the systems biology work, going to be synergistic.

Then, in another project, we've been really focused on ovarian cancer. And we've more recently found that we can deliver a molecule called a cytokine that stimulates the immune system in a way that is more accessible for these ovarian cancer cells. Our nanoparticles are able to stick and bind to the outsides of the tumor cells and then act as a kind of depot to release the cytokine. And because they're not taken inside of the cell, but rather sit on the outside, that cytokine, then, is able to access the receptors of neighboring cells and cause the generation of Interferon, which is the key regulating molecule in the innate immune response. So, we found that we can actually effectively get an immune response to ovarian cancer, which is much more traditionally an immune-weak tumor. Typically, ovarian cancers have not been addressed with regular immunotherapy approaches.

Zierler:

What does that mean, immune-weak?

Hammond:

They don't have a large number of immune cells present in the tumor, and the immune cells that are present aren't very active. So, if you deliver one of the most common immunotherapies to ovarian cancer, you don't really get a response because there really aren't any players there. And so, you're not able to enact the kind of change that we're seeing with lung cancer and melanoma. So, if we're able to generate what's called a hot tumor, which is a tumor that does have immune cells present, then we can not only get a more active, engaged immune system that is able to attack the tumor, but we can then apply the new immunotherapies that have been introduced over the past few years. Those immunotherapies work by essentially preventing other cells from turning off the immune cells. But that doesn't work if you don't have any immune cells to begin with.

Now, if we bring the immune cells in, we activate them, some of that deactivation begins to take place that immunotherapy then takes care of. And now, we have a tumor that is going to be responsive in the same way that we see for melanoma, where immunotherapy has been a real game-changer, for example. And ovarian cancer matters because the cure rate, the survival rate has not been improved for decades. It's been a much more intransigent cancer because it gets resistant fairly easily. So, those are two cancer areas.

There's a couple of other projects that are new that I'm excited about that speak to other kinds of disease challenges. One of them is that we have designed a charged molecule, so the polyelectrolyte theme persists, that is a carrier of a protein. That protein can stimulate regeneration of cartilage. Now, the protein itself has been known for a long time, but if you inject it into a joint, it rapidly gets cleared away because, again, we get that–the chemical engineering version of this is that you have mass transport that's very rapid. So, it turns out that cartilage is this really negatively charged matrix. It's, like, a net of negative charge. And there are only a few cartilage cells, they're very dispersed across the cartilage. Because cartilage is mostly matrix, and it has no blood vessels. So, these chondrocytes, or cartilage cells, they just sit there. And typically, they're dormant, unless there's some need for regeneration. But they need to be stimulated to regenerate. Because it's already formed its tissue.

So, what we developed was a charged sort of carrier that we attach the protein to, and that charged carrier is positively charged, and the cartilage is negatively charged. And we designed it so that it's sticky, but not too sticky, so it gets in and moves, and gets in and moves, and kind of penetrates the cartilage. Which is important because we can't use blood vessels to get into the cartilage. And ultimately, it stays in there for a long time. We've increased the half-life in the cartilage by a factor of ten. So, it means that we can then have this protein that's tagged on, interacting with the chondrocytes and the cartilage for days and days. And we found that that allows regeneration. So, now, we have a project in which we're trying to move this into dogs, and see if we can improve this for Osteoarthritis.

Then, the other project is also newer, and it's a collaboration with Boston Children's Hospital, my collaborators there, which include David Williams and David Scadden. In their labs, they have been doing sort of gene therapy approaches. And here, the disease of focus is Sickle Cell Anemia. And Sickle Cell Trait and Sickle Cell Anemia are the result of a genetic mutation.

So, in simple terms, they have a CRISPR-like tool that can cut out that gene or repair that gene. And the idea is, "How do we get this into patients outside of what's now being examined, which are cell therapies?" There's been a lot of really exciting work recently where they take the cells of a patient, they engineer the cell outside in a tissue dish, and they clear a certain set of the bone marrow cells out of the patient and then re-inject the patient with these cells. It's pretty invasive. Exciting, positive results. Pretty invasive. Really expensive. You're not going to get to a huge community of African Americans or people of African descent, and they are going to be one of the populations most affected by this disease. So, the idea is, "Can we design an injectable form of gene therapy that will find its way to the cells of interest, so targeting, and will deliver this gene so that it gets inside the cell?" Now, we have to get it to the nucleus so that CRISPR can do its gene modification work. So, we're working on the carrier that will encapsulate the gene drive, so to speak, that will do this work and target it specifically to the cells that we need to target to be effective. And that's a newer project. We're really excited about it. Going to be hard work, but it'll be good.

Zierler:

Yeah, yeah. Paula, have you had any real satisfactions in terms of clinical applications with your research where you can really see, "Here's a patient, here's a direct impact, and I had something to do with the research getting there"?

Hammond:

Although we haven't had clinical trials with our work yet, I'm hoping that we will. I think that the Osteoarthritis project and some of our cancer work might be where that will probably happen. For cancer, we're working with collaborators that, with these combinations, would be able to help us access clinical trials more readily. So, I'm hoping that in ovarian cancer, and possibly in glioblastoma, that we can get there, actually. And with Osteoarthritis, our most recent set of funding is to move from the rats that you start with to dogs. And you have to get to these bigger animals with any sort of bone or joint-related disease before you can move into a clinical trial. But we think that at the end of that work, we should be much closer to where we want to be.

Zierler:

Well, good luck. I mean, wow. Paula, for the last section of our conversation, I'd like to ask a few broadly retrospective questions about your career, and then perhaps, a few questions sort of looking to the future. So, first, I'd like to ask another question coming from the vantage point of my world in physics, which is, in physics, we have a very well-developed sense of mysteries, right? What is dark matter? How do we incorporate gravity into the Standard Model, right? Big mysteries that we know are there, but we just don't understand. Would you say that in chemical engineering, there are those categories and gaps where there are big question marks that chemical engineers are aware of the gap in knowledge and have some sort of pathway to figuring out how to close those gaps in knowledge?

Hammond:

I do think that's true, absolutely. A lot of those are shared gaps because chemical engineers typically, in each of these different categories in which we work, energy, and reaction, kinetic design, drug delivery, and biomedical, biomaterials, biotech, have a fundamental science, and we have often this overlap with our fundamental scientist colleagues, where we're trying to address a critical question. And sometimes it's a method that is at the core of the big challenge. "Will we ever be able to simulate X-numbers of molecules or X-numbers of particles in one ensemble effectively and efficiently so that we can become predictive?" That's an example of a question that chemical engineers have asked and tried to address.

In my field, "Can we find a way to design a materials system so that it is more efficient and effective at getting across that blood-brain barrier?" Right now, we're getting across, but 2-3% is better than zero, but we have some room. We have some frontier space. And there's some fundamental questions behind how we can do that. And they involve transport as well as biological coordination with the materials that we design. So, there are some really critical questions, and I think that blood-brain barrier question, although it's been around for a long time, is one of the ones where there could be breakthroughs in the coming years. And chemical engineers will contribute to that. And again, this is more in my field, but, "Can we design a materials system that can go through the bloodstream and be effective in terms of transport, maintain a long half-life in the bloodstream, but target or accumulate in one specific organ?"

And that, again, I think is a chemical engineering question from the standpoint that the body is one big sort of system in which there's flow. And then, there are these reservoirs, and organs are like these reservoirs in which you can get accumulation, if you have some designed affinity, but you have to get beyond the barriers of the blood vessels. We have to get through them to get into organs. Or you may have to get through a mucosal barrier. Or another kind of physiological barrier. So, how do you get through to get where you need to go? And that's a transport question. I think in other fields, we have the same kinds of things. So, in catalysis, it's all about, "Can we understand how that reaction happens?" Which takes us back to fundamental physics and chemistry, really. We get down to the orbitals and how those orbitals are engaged by a catalytic system. "How do we tune it so that it's so beautifully specific that only this reaction takes place, and not these other three or four?"

So, these questions often exist when we break them down at the interface between where scientists and engineers work. And so, always with the fundamentals, you end up having, amongst the group of people that you want to interact with and learn from, those fundamental scientists, those physicists, the biologists, the chemists are going to provide the insights that you need to be able to understand how to make your system engage with that system.

Zierler:

Paula, similar question to the one about graduate students. I certainly don't want to burden you with a discussion about all of the amazing awards and recognitions you've received over the course of your career, but I do wonder if there's one that is most personally meaningful to you, either because of the research associated with the award, or as a matter of scholarly affirmation with which your colleagues hold you in such high esteem.

Hammond:

Well, for scholarly affirmation, it would be my recent elections into the National Academies of Medicine, Engineering, and Science. Kind of happened in that order. Because those are huge validations of recognition by my peers. And so, that means a huge amount because of the nature of that. It also means a lot because the National Academies are about service. And they're about really providing a voice of science to our government. That was why they were founded, and I think it inspires me. I like to think about it as one meaningful way in which I may be able to help voice to policymakers, to influencers what is important about science, and why we need to maintain it, and why we need to listen to it. So, I think that has sort of a dual meaning to me because I've always had an interest in how science influences our society, our government, and how it can help us. And I think that the National Academies sits at that nexus.

In terms of personal, there are a couple. The Margaret Rousseau is one that is meaningful to me for a couple of reasons, as she was among the first women to get a PhD in chemical engineering. And she has an incredible story, I think, of helping to save the world through a sort of biopharma, biochemical manufacturing of Penicillin. Penicillin had been discovered, but you can't do a lot when you can only make this much. And this is really where chemical engineering plays a role in the bigger world. We're still at that center of the same kinds of pharma manufacturing wonders that have allowed us to have 100-million doses of Pfizer and 100-million doses of Moderna ready for us after just an eight-month incubation period. So, Margaret Rousseau represents that part of chemical engineering as well as the impact of women in the field. And she's from MIT. So, that adds something personal as well.

And I also recently received the Percy Julian Award from NOBCChE. And that really is a recognition from my own community. NOBCChE is the National Organization of Black Chemists and Chemical Engineers, and they provided a short-term fellowship when I was in my graduate life. I think in my third or fourth year. Just going back to that and going back to some of the roots of other African-American scientists and engineers there to support each other and affirm each other's work, and to promote the importance of science to the rest of the community, I think, is really important. And to increase the visibility of people of color in our field. So, receiving the Percy Julian Award, which is the highest award that we have in this organization, was very meaningful. Again, selected by my peers. And Percy Julian, of course, being a hugely impactful chemist with a very interesting and inspiring life. So, that also had personal meaning.

Zierler:

That's a great segue to my next question, which sort of bridges chronologically retrospective, and present, and the future, and that is, I don't know about you, but for me, 2020 can't end soon enough. And one of the things that's been so painful this year has been, it's been a year of terrible racial injustice and a racial reckoning that we need in this country. And as you well know, STEM has not been immune from these issues. And this year, as a community, with #ShutDownSTEM, there's been an opportunity of introspection. And so, I want to frame this question in very real terms because I think it's so important that that isn't just a day on the calendar, it's a day that people just sort of were introspective, and then life gets back to normal. So, I want to frame the question in this way, and I'll use examples of people whose life experiences you might well recognize. I'm so privileged in my work to talk to people a generation previous to you, such as Dr. Shirley Ann Jackson, and a generation younger than you, like Professor Thomas Epps. And in hearing both of their stories, I often draw lessons about experiences that they've had that seem very long ago in terms of hearing Shirley Ann Jackson talk about things from her childhood or her experience at MIT. And it's like, "Are we talking about 50 years ago? Or are we talking about 150 years ago?"

Hammond:

Understood, absolutely.

Zierler:

And then hearing things that Thomas Epps talks about today where it's like, "Really? Today? This is stuff that you're still dealing with today?" And so, in your generation, sort of right in between both of them, I want to ask you to sort of broadly reflect on experiences that you've had or from your parents, things throughout your scholarly, professional career where from a racial injustice perspective, there are things that you've experienced where you're just thinking to yourself, "I can't believe this is something that's happening today," and on the positive side of things, things that you might have experienced earlier in your career, but for which now, real positive change has happened, and we've crossed the rubicon. And there are things that are verboten or unacceptable, or people have just gotten beyond that, so it's not a part of your daily reality. So, I guess that's a real longwinded way of saying, where do you see in your own life the real progress happening, and where does the progress remain as urgent as it might have been 20, 30, even 40 years ago?

Hammond:

I think a few things. I'll start with the latter and then move to the other. Things that we still need to do. Numbers. Oh my God. The fact that, for our graduate students, we're still looking at something that's more around the range of 4-5% when we're lucky of African American, or all underrepresented groups, is really saddening. Because those same incredibly low numbers have been there since I was an undergraduate. And so, we see this largely in the graduate school population. What we see is that students are somehow still not getting brought into graduate school at the numbers that we need, and we really need to have those voices present at the table.

The dream that we need to make it to is to have any sort of typical gathering of engineers, or chemical engineers in my case, but scientists and engineers, have significant Brown and Black faces around the table. And to have women around the table in even numbers. And I think we've made much more progress on women, but not progress in the way that we need to with underrepresented groups. There's a real difference in those rates of progress, which is sad. And I think that makes a difference in environment because it makes that critical mass that we need so much less attainable if we're not increasing the rate at which we're bringing people into the field. And that critical mass is meaningful when you have enough people present that it's not a thought that somebody is of a given race, in terms of their sense of belonging. I think it's not just the sense of acceptance by others present, but a sense of belonging, that you are not only there, but you're of that group, that you can speak with ease, that you can engage without any sort of inhibition. And reaching that point where there's not a presumption about you and your abilities because of your race. So, I think that is the thing that is most critical and most on my mind right now.

When I think about my own experiences, the things that I experienced, they were interesting. I think at MIT, when I was an undergrad, I know that there were areas and situations where I think, in particular, our peers would sometimes express, "OK, you probably got here because of Affirmative Action. You don't really belong. You're probably not good." These kinds of presumptions were implicit sometimes. They weren't expressed, but people acted on them. But we would also get these articles in the Tech that would more explicitly state, "What are we doing admitting these people that don't belong?" etc., and implying that somehow, we're not as good. And those were, at that time, things that I would see in the Tech, reading as an undergraduate, and you're thinking, "Well, OK. You don't think I belong." And for me, the response, of course, is, "Well, I'll show you," right? But you shouldn't have to have that response. You should not have to have the feeling that your colleagues don't think you belong in an environment where you rightfully do. So, I definitely experienced that as an undergraduate.

When in was at my first work experience, as I mentioned, there were comments and references about women engineers, and there were implications and explicit things with respect to race that were very much in your face at that time. And I think, at that time, people thought these were acceptable things to say or do. Sometimes jokingly. But no. I think that we have gotten beyond some of those more explicit behaviors. I think people are more refined. But I fear that these last several years, especially with the more recent administration, have amplified the voice of people who feel justified in making claims against people of color, and pushing agendas that minimize the issues of people of color, and who, frankly, put forward some white supremacy ideas as if they were mainstream. And so, I have to say, I fear that without significant focus there, that that environment will influence our science and engineering culture as well. And we have to be vigilant and make sure that those aspects don't creep into our own cultures.

Zierler:

To make it hit home even more, to the extent that progress is not linear, that things don't just get better every single year, and it's not a simple story, I wonder, going back to earlier in our conversation, some of the lessons that you drew from your parents about how to react to these situations. In what ways is the advice that you got from your parents dated, and what ways, as a parent yourself, are they, for better or worse, as relevant and necessary as ever?

Hammond:

I think that you still have to outshine to get ahead. I think that there's still a need to be incredibly polished, to be incredibly present, and to be an over-performer on some level to sort of become sweepingly engaged with the rest of the community. I do think we're getting a little better. I think we've become a little bit broader in our thinking in general. But I think that some of that advice still applies, unfortunately. I do think that you cannot expect or anticipate that your efforts will be evenly received as the equivalent if the person were white or male. And we all carry implicit bias. We all have to work against it.

What I do think has changed is that our colleagues have become more cognizant that this exists, and for that reason, are able to compensate for it more effectively. So, although it's not gone, it's not as critical as it was. And I think it's allowed a more diverse set of voices. Because we are, as with any group of people, a very diverse group. And it means that people with many different perspectives and many different means of expression, etc., are present in our field. And that makes a huge difference. I think the same is true for people of color in the LGBTQ community, for example, who I think now feel like they have more of a voice than they did before and more visibility than they did before. I think as we advance, we are becoming better at recognizing the diversity within our communities and putting all of them forward and upward. I think the community has become better at creating support networks and mechanisms. So, we're making some progress.

Zierler:

There's a duality to diversity initiatives. On the one hand, there's simply the social justice matter, that people deserve a chance. But from the science perspective, diversity is good for science, that different worldviews and different perspectives actually, scientifically, exert a positive influence. I wonder if that is something that's becoming more recognized in the field.

Hammond:

I do think it is. Back about ten years ago, I headed a race initiative at MIT to look at the experiences of Black faculty at MIT. And one of the outcomes of that work, which involved interviews, and surveys, and so forth, one of the key issues is that people would tend to think that increasing diversity decreases excellence, when in reality, increasing diversity increases excellence. And trying to get that message out to especially the more–

Zierler:

It's like, how do such smart people have such dumb ideas?

Hammond:

Exactly. Exactly. But that is definitely one of the sort of memes of diversity efforts, is that there are a number of people who say, "Well, as long as we don't compromise our values"–well, we're expanding the excellence in our department or our university by bringing in diverse perspectives, and that's going to improve our science. There's no compromise here. This is a game. We need to do this. Are we going to be number one? Then, we need to do this, right? And so, that counterargument has to be present. We have to be vigilant. We have gotten better at it. More people are aware of the research, which actually shows this to be true. More people are aware of just the general idea of how we gain from these different perspectives, which makes sense.

Zierler:

Paula, for my last question, I want to look forward. I want to ask you, what are the things that are most exciting to you from a basic science perspective, just in terms of fundamental discovery in the areas that are most intellectually compelling to you? And what are the areas that you're most optimistic about on the applied side, in terms of really contributing and making a difference that improves people's lives? And I wonder if I can frame that question as maybe a pie chart of all of the different components that go into scientific advance. So, it would be funding, it would be great collaborations, it would be luck and serendipity, it would be grinding out those long days in the lab, right? All of those elements that contribute altogether into discovery. What are those areas in your research agenda that you're most optimistic and excited about, and what are the most important elements that are most likely to push those discoveries to fruition?

Hammond:

And this is from the perspective of my own research?

Zierler:

Absolutely.

Hammond:

OK. I probably hinted at some of these already, but I do think that addressing the barriers or delivery is going to be huge. So, I mentioned the blood-brain barrier. But there are others barriers. To get into the lung, for example, which would be huge if we really want to be more effective at treating infectious disease. Getting at some of the other organs that are key to disease, especially inflammatory disease. So, I think there's going to be a lot of advance, especially in understanding how nanomaterials make their way across those barriers, and that will require some fundamental thinking and understanding.

I also think that there are some ways of using genetics to understand which systems and which diseases might be amenable to nanomedicine treatment. And that requires some deeper thought about how cells interact and why. And with our materials systems, under disease states. So, I'm very excited about that. I'm excited about the intersection of the ability to manage the immune system using nanomaterials to drive the immune system. So, I am interested in that intersection because it addresses not only disease states, but also, perhaps, ways of monitoring the immune state in healthy humans and really addressing different kinds of conditions. So, those are two that immediately come to mind. I'm really interested in RNA and mRNA.

Zierler:

mRNA is in the news right now. It's very exciting. It's going to save us from COVID.

Hammond:

It's very exciting. And disclosure here, I'm on the Scientific Advisory Board of Moderna. And in our own lab, we're working on the delivery of nucleic acids, including siRNA, mRNA, DNA. All the NAs. So, I've always been a huge fan and believer. So, this story that's been unfolding, to me, is like the big victory story. And the siRNA delivery story, would've been 2018, Alnylam, both of those companies, I know well and know the scientists from them. It's a part of what has excited me about the new world of medicine is genetic medicine, maybe, is a general way of putting it. So, that excites me. And along with that capability comes the need to direct it to the right place at the right time with the right timing. And that's where I get excited about engineering systems that can manage to protect these systems, get them through to where they need to go, and help them make it to the final point, which is often the cytoplasm or nucleus of the cell you're targeting. So, mRNA and everything around it.

Then, the other is, in general, that I think we have been very interested in spatial temporal control of release from surfaces. And the idea here is, we have some projects in which we very gradually release grow factors, nucleic acids from a surface in order. And an order that is, essentially, consistent with a healing process, for example. So, we're looking at this as a way to direct wound healing for wounds that don't close, we're looking at it as a way to prevent scarring or fibrotic wound healing in something like third-degree burns, looking at it as a way to control bone regeneration and growth, making sure that you have blood vessels that form first and then bone that forms around it. So, I think that in the area of regenerative medicine, the ability to control spatially and through time, the release of these very potent biologic drugs is going to be very interesting.

Zierler:

I can't help but note that you're crossing barriers sociologically with regard to race and gender, and you're crossing barriers biologically within the body. Can't help but point that out.

Hammond:

That's great. I hadn't thought about that. But that's great.

Zierler:

Paula, thank you so much for spending this time with me. It's been truly special and delightful to hear all of your perspective over the course of your career, and I'm deeply appreciative that you were able to do this. So, thank you so much.

Hammond:

Thank you, David. It's been great talking with you.