The research from your highly cited papers on self-assembled monolayers dates back to the early 1980s. How did you launch this research and, for that matter, what exactly are self-assembled monolayers?

Well, by training I was a physical organic chemist. And the things we were doing back in the late 1970s, when all this started, was working with small molecular mimics to understand how surfaces work, catalytic reactions, things of that sort. The idea was that a molecular mimic could tell you how these kinds of ensembles work. When I finished graduate school, I got a job at Bell Labs—this was 1980—and they never really told us what to do. Since I was interested in surfaces, I started thinking about how I could mimic surfaces, and I had this idea to make these organic self-assembled monolayers, which can be thought of effectively as model organic systems. A self-assembled monolayer is a molecular thin film that forms via the spontaneous organization of molecules on a surface. This self-organization is thermodynamically directed and leads to the formation of thin films that are only one molecule thick and contain very few structural defects.

  What was it about the 1992 paper, "Synthesis, structure and properties of model organic surfaces," (LH Dubois, RG Nuzzo, Annual Review of Physical Chemistry 43:437-63, 1992) that made it so significant?

That was one of these end-of-the-era kinds of papers. At the time, the field had literally exploded. There was just so much activity going on studying synthesis and characterization of these organic surfaces and their applications. So we put together the most complete picture of the kinds of experiments that had been done and the kind of structural and physical understanding that had come out of those experiments. It was meant to be a summary of everything we and others had done to that point, with a very complete set of references of what had played out to that point. We wanted to cover the kinds of analytical protocols that had been developed as well; things that were done to characterize that kind of structure. That paper really laid out the structural understanding of the state of the art at that point. Also it tended to suggest potential applications as well, at least as we understood them. Scientifically, it probably wasn’t my most important paper, but it was a very complete summary of the state of the field. It was also kind of a finale for me, as well, because that was the year I left Bell Labs where I had done all the work.

  Do you consider the 1991 paper JACS article, "Comparison of the structures and wetting properties of self-assembled monolayers of normal-alkanethiols on the coinage metal-surfaces, CU, AG, AU," (PE Laibinis, et al., JACS 113[19]: 7152-67, 11 September 1991) your most important scientific contribution?

Probably. That was a structural tour de force. It really was. It was just one of the greatest papers I have ever been involved with. The thing I have to tell you—and this is really, really an important point for any understanding of this area and modern science, in general—the thing that made this work was first and foremost an environment that lets you pursue crazy, stupid ideas. When we were doing that work there was very little accountability of how likely this was to work or how it fit on the roadmap of other people’s ideas. This was completely outside the orbit of Pluto. The other thing that made it work was the wonderful collaboration that existed between all the people playing in this area of science at that time: Larry Dubois, George Whitesides, and Dave Allara. Dave and Larry were at Bell when I was there, and George was at Harvard. We would send things back and forth by fax, which was a new thing back then, and we couldn't wait to see the next result come out. And then we put together this really complete package of understanding that was phenomenal. It was the most fun I ever had doing science. Every day, there'd be something new, and we'd wind up in a different place. We really figured out how to do the nitty-gritty mechanics of these measurements, and absolutely pushing to the limits to get a complete understanding of the properties, function, and structure.

  What was the biggest challenge in doing this research?

When we came up with the idea of self-assembled monolayers, it was probably a great idea in one way but a crazy idea in another. In 1980, the characterization part of this whole endeavor was basically non-existent. How do you test the structure? How do you test the properties? There were just no techniques for doing that, and that was the hard part about the science, getting to the point where we could actually understand what these things were, how they worked, etc.

  What was the most gratifying aspect of the research?

It turned out these systems were much more useful than we ever imagined. You could do all kinds of things with them. They became a big area of research in chemistry. That was definitely gratifying. And we had a lot of fun.

  What do they do?

One thing you can do with these is you can control wetting interactions. In other words, you can control how liquids spread on surfaces. You can also control how cells adhere and how electrons tunnel across an interface. You can control how proteins bind and how molecules grab onto DNA. It turns out that they are a very general platform for developing complicated organic structures at interfaces. But the ideas played out in a lot of different areas as well. So now these systems are the basis of biological assays, DNA testing platforms, some gene chip ideas are built on them, and detection schemes, as well. The resist chemistry for lithographic patterning that people are very excited about is based on these ideas. They said a long time ago was that there was no way a latent image, a pattern on a monolayer, on a phase that is one molecule thick, could generate a useful structure in a thin film material. That turns out to be just totally wrong. They do have characteristics that lend themselves to doing that, which turns out to be just amazing.

  And what are your long-term research goals?

My biggest goal is to understand this whole notion of what self-assembly is. Most of the stuff we have done, which is really well regarded and well understood and broadly disseminated, are on chemistries in which molecules organize and minimize free energy. They form this organized structure and minimize free energy because they bond strongly to the interface—that is to say that the enthalpy of the molecular interactions tends to dominate the problem. That is really a straightforward assembly process. You design molecules or sets of molecules that put themselves together because they minimize free energy in this way. What's more interesting is how to get organization in a system that’s not stable in that kind of sense. You can have temporal stability because the system is actually dissipating energy. If you stop dissipating energy in the system, then that organization would go away. We don't really have a good language for this yet. Some people might call it driven-assembly or dissipative assembly. This is a field that really hasn't been born yet, and we don't know what the good experimental models are, but we can point to really beautiful examples that exist in nature.

As physical scientists, we need to really learn how do use these ways of organizing structures in more complicated ways than we can do now. I think that’s going to be a really powerful idea in research over the next 10 years or more. I think it's one of the things not really on the road map yet, and it’s not really clear exactly how that will play out, and in what kind of context, but I'm sure it will be important and fascinating and it's what I hope to pursue.

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