Scott White was a young University of Illinois researcher in 1998, eager to share his excitement about the potential of self-healing materials and possibly initiate a collaboration with a young chemistry professor he had found through a search of the U of I Web site. White found himself sitting with one of his students in Jeff Moore's office, putting on a one-man show for a one-person audience - a silent one person audience.

"He was very pleasant and nice but I was doing all the talking," White said. "I told him this is what we want to do and waving my arms around a lot. He was just looking at us and being pleasant. I think he said something like 'yeah, well, it sounds interesting, I'll think about it.'"

Moore was actually thinking he already had enough projects, thank you, on his plate without adding another. But White isn't the type to give up easily, so after not hearing back from Moore he went to visit him again.

"I guess Jeff just thought 'well I'm not going to get rid of him unless I say something,' so he started saying a few things," White said. "So it just sort of organically evolved from that point forward."

What evolved was a collaboration that not only led to a seminal paper on self-healing materials published in Nature in 2001, but also to a longstanding partnership between Moore, White, and Nancy Sottos that could serve as a model for doing interdisciplinary research.

Sottos is a faculty member in the Materials Science and Engineering Department, while White is from Aerospace Engineering, and Moore from Chemistry. They are key members of the Beckman Institute's Autonomous Materials System group who have seen their initial success with the Nature paper validated as their work now serves as a pillar for this fastgrowing research area. The work has also expanded into a research line for the trio that is generating new discoveries and attracting increased funding.

Sometimes researchers will collaborate over a number of years as these three have, but the approach of Sottos, White, and Moore to research and to working with each other and with students is as distinctive as it is successful. Their students may come from different disciplines but they often become blended in projects as interdisciplinary interactions are the norm in their group. Their research efforts draw a lot of attention but all three are happy to share the spotlight with each other and with students.

In a previous article, Moore described the partnership this way: "After working with someone that long you find mutual interests and I just enjoy being with them. My life at the University of Illinois is greatly enhanced by this group and that's not just lip service. I can tell you honestly there is probably a good chance I wouldn't be here right now if it wasn't for the connections I have with this group."

Recently, the trio sat down for an interview session to talk about the origins of their partnership and their first paper on selfhealing materials, as well their approaches to research and working with students and each other.

A Collaboration of Opportunity and Necessity

The partnership began when Sottos arrived at Illinois in 1991 just a few months after White, occupying an office at Talbot Lab that turned out to be right next to White's office.

Sottos: It also turned that out that after I met Scott I found out that we had been running in the same circles for years but had never met each other. We had gone to some of the same meetings as graduate students. We both have backgrounds in composite materials but with a subtly different focus. Scott's focus when he first got here was on how to make a composite and how to integrate many things into a composite material, and my focus was on small-scale experimental methods, how the different components in a composite interact at almost a molecular level. Throughout our first couple of years we used to go to lunch and discuss sort of blue sky type research projects and how we might collaborate, because as assistant professors you are kind of in a track doing your own thing. At some point the idea of selfhealing came up, which ties in with some of the things that both Scott and I were working on about adding extra functionality, sort of unusual multi-functionality, into composites, into polymers, giving them functions that they don't normally have... Self-healing became one of those functions and we got a very small research grant from the Army Corps of Engineers to look at concepts for self-healing. That was just an engineering study, though. What came out of that study was that we thought that microcapsules were a good idea, and that microencapsulation was the way to go if you wanted to bring in this self-healing functionality. We quickly tried a couple of chemistries that we knew but they were somewhat limited. Then Scott went to visit Jeff.

White: Nancy and I and Philippe Geubelle worked together for a while thinking about concept development for self-healing systems. We had a small grant around 1995. We started hatching out ideas and the microcapsule concept was one we were looking at. With the concepts that we wanted to pursue, it became very clear very quickly that we were in over our heads in terms of the chemistry involved. Then I looked on the U of I Web site and did some searching for stellar, outstanding, wonderful chemist with knowledge of polymers and it came up empty (drawing laughs). But then I found Jeff's name and went over to his office with a student of mine at the time... I took it at face value that he was actually going to think about it and get back and we left. But he didn't get back, so I said we need to go talk to Jeff again. So we went back.

Sottos: As Jeff will tell it, Scott was persistent. Once Jeff got involved, he suggested the chemistry that we eventually used in the Nature paper. It was something that Scott and I would never have dreamed of using on our own. It was very new, very different, and we just would not have had the experience to work with the catalyst.

White: We put together a proposal, all of us, and the thing that really got us going forward was the Campus Critical Research Initiative award. They gave us some money to actually have students working on it and we collaborated and started having joint group meetings that started evolving the research.

Patience Pays Off with Nature Paper

The Nature paper in February 2001 turned out to be huge news in the scientific and popular press. It reported on using microcapsules for autonomic, or self-repair, of cracks in polymer materials. The process works, according to the Autonomic Healing Research group's Web site by "incorporating a microencapsulated healing agent and a catalytic chemical trigger within an epoxy matrix. An approaching crack ruptures embedded microcapsules, releasing healing agent into the crack plane through capillary action. Polymerization of the healing agent is triggered by contact with the embedded catalyst, bonding the crack faces." The discovery was carried in newspapers and Web sites worldwide and earned a front page story in the Washington Post. The work has since expanded to self-healing microvascular composites and recently produced a paper demonstrating a practical application of the microencapsulated system.

Sottos: This project just sort of percolated from the bottom up, which is not always how projects go. And it wasn't like there was this whole community of people and this whole gigantic literature on self-healing; there were just indications that this is a good idea. Some polymers like asphalt tend to self-heal, that is a word that was used in literature, and there were people who did polymer welding but the notion of building this into any material was brand new.

Sottos: I have to say that Scott has been our cheerleader. It was a difficult problem and it took a lot of things to come together correctly. I would say that I was pessimistic more than once along the way. Scott's a good leader in that respect; just keeping everybody moving forward even when it seems like the research isn't going the direction you want it to.

White: I don't give up. That's the problem (laughing).

White: The one thing that gets to the heart of that is that the publication of the Nature paper was February of 2001 and we had started in 1995 on these simple tests. The first positive test we got was late 2000. That's five years of failure after failure after failure.

Moore: The key was the 'bullet' test. It's simply an object in the shape of a bullet. Sottos: It was a little cylinder of polymer that had the microcapsules and the catalyst. It had the healing components in it. So it was easy to make a whole bunch of these and you would just tap a razor blade into them and bring them back together. Then we would have students that would try to pull them apart and we would measure how hard it was to pull them apart on a scale of one to five.

Moore: Not scientific. (laughs)

Sottos: There were no forces measured, it wasn't quantitative. Then it became that the strongest student in the group was supposed to pull them apart and if it was a five on his scale then we knew we had healing. We didn't publish that (laughing). It was just a good example of how those initial meetings were actually pretty fun. We've been having fun for quite a long time. We actually got to know each other very well as we were writing the Nature paper."

Collaborators and Friends

The three have worked together for more than a decade now, and their collaboration shows no signs of slowing down. White was instrumental is landing a large AFOSR MURI grant in 2005, while Moore was the principal investigator on another MURI grant this past year. Sottos describes herself as the person who looks to the details of the experiments, while Moore is referred to as the group's "rock star chemist." In a previous article, Moore said this about their collaborations: "None of us are trying to focus the spotlight on ourselves; it really is a group activity. We all know we can't do it alone. For me personally this is a level of science that I know I could never do myself but is incredibly enjoyable to be involved in. We all take different leads on different portions of it." He also described White as the team's "self-healing guru."

Sottos: (smiling) I believe in the article Scott White was referred to as a visionary. That is absolutely true.

White: That's what they say when you don't really do much (drawing big laughs).

Sottos: No, having the bigger picture of how everyone fits together is an important part. I tend to be the more detail-oriented person who is going to do the experiment. We all work on the microvascular composites, for example. Rather than bullets with one through five, I will think about how the experiment is going to demonstrate the healing and make sure that it is precise and that it's done correctly.

White: In any of those (research projects), along the way there were all kinds of times where any of us at one point would think 'forget it, this is too hard it's not going to work.' But you see multiple examples of a long process coming to fruition and being successful and it is extremely gratifying. It's really what motivates me to continue to do this.

Moore: I think part of the reason that we can make these long-term projects work is because it's hard to bail when you know you've got two other people who are still there going hard at it. Why would I walk away if they are going to hang in there. We sort of reinforce each other that way.

Sottos: When I started with this, the selfhealing and interdisciplinary research was such a small part of my research program. It would be hard to go backwards, I wouldn't want to.

Sottos: When we were joking about Jeff being a rock star chemist, which of course he is, one thing that is important about this collaboration is that often engineers are kind of itching to work with scientists but not all scientists want to get involved with technology and engineering because it is a different kind of field. The benefit to engineering is often pretty clear. Jeff is awfully good at working with us non-purists.

Moore: We all have a competitive spirit I would say. We're also pretty unselfish. I think that's a key thing too. It's for the good of the group as opposed to any one individual. People have asked (about our collaboration) because these papers and this topic have gotten a lot of press. There is a lot craziness associated with this topic. Normally when you work in a group it's hard to survive because everyone wants the spotlight. But that actually settles out very well for us.

White: It's very clear that this mode and the Beckman support and the space that we have and everything we utilize here is the model of how to do this. Others are looking at it and trying to catch up. I'm very grateful that we have this opportunity here and it's the way of the future and the way it should be done.

Group Dynamics, Student Interactions Produce Successful Research

Teaching and interacting with students on research projects are vital parts of their work at the University, say White, Sottos, and Moore. In bi-monthly meetings with the Autonomic Materials Systems sub-group that works on self-healing projects, students give power point presentations to 20 to 30 fellow students, post-doctoral researchers, and faculty members, including White, Sottos, and Moore. During the meeting, probing questions about experiment choices, suggestions for improving results, and other contributions flow from the faculty and often from the students present. It's a process that both prods the research forward and gives the budding scientists a chance to test out their work in front of an interdisciplinary audience of mentors and peers. "I think the more chances that I get to present the work the better scientist I am going to be because people ask questions that I never would have thought about," said group member Mary Caruso, a Ph.D. candidate in Chemistry. Caruso was lead author with Moore, White, and Sottos on an important new paper that came out in Macromolecules describing an improved, more practical method for creating a self-healing microencapsulated system. Caruso said she came to Illinois to work with Moore but now "The three of them all play a role in our projects. It's very supportive. I absolutely love it because I was trained as a chemist but now I am doing more materials science. I'm still working on the Ph.D. in chemistry even though I don't really do chemistry every day. I think the collaborative efforts that we have (in the group) are fantastic."

Sottos: I think our approach to research and our academic lives are similar. Even though we are in different areas, we have a similar philosophy about our role in the University, University research, how you interact with students. That's an important part because we interact with students similarly. Getting good research done is more important than the fact that it's my research or Scott's research or Jeff's research. Achieving something new is important, and having students involved, training students in a certain way, building a collaborative group, are important.

White: I think we all subscribe to the belief that the students are the most important thing coming out of here. It doesn't matter if it's my student or Jeff's or Nancy's; in fact we co-advise almost all of the students. We don't claim ownership of a student; it's that person that we're trying to educate, get their feet on the ground and have them succeed.

Sottos: Definitely there is a lot of coadvising and of course they belong to their departments but the group has an important role for them. They do need to interact in the group in order to make progress on their projects. The group has a dynamic to itself. I think that's the unique part, that the combined group has a dynamic that is separate from the individual groups that each of us have. We had a couple of students, key students, who crossed boundaries. There is a graduate student chemist who was working with Jeff; he made a full transition to understanding a lot of engineering. He used to ask these amazing questions, really pertinent and insightful, at group meetings. This would lead Scott's engineering students to take a much harder look, dig deeper into the chemistry, and ask in-depth questions so that they can also talk the talk. It's been a nice process to see that happen. It used to be more of us questioning students.

White: This is symptomatic of interdisciplinary research. The questions that you might get from a chemistry student asking a mechanics student about their work opens up new thoughts for the mechanician, and the same goes both ways. It advances the level of everybody. That is key to the success that we have had. The group has grown and meshed so well.

Moore: An example of that is some recent progress (with the Macromolecules paper). One of my students, Mary Caruso, drew from something that Nancy's student had already made progress on. The two of them started talking and then, instead of us basically driving the research, it's safe to say that the two of them were driving it. The two of them would come and shows us results. Mary is so much in the group; at core she joined my group but I can't say that she is just a member of my group. She's lost her identity (he said with a laugh) and is no longer squarely chemistry, and for this work those are some of the best students. They're willing to give up their identity and do what the problem is demanding.