The Kavli Prize Presents: Understanding Molecules [Sponsored]

The Kavli Prize Presents: Understanding Molecules [Sponsored]

July 29, 2022 0 By bimola

This podcast was produced for The Kavli Prize by Scientific American Custom Media, a division separate from the magazine’s board of editors.

How do you make a piece of glass repel water? How do you protect metals from harsh chemicals? Scientists have been puzzling over how to transform surfaces for centuries. 

Jacob Sagiv made a giant step forward in this field of research by discovering a way to transform a solid surface with an ultrathin layer of molecules. 

He shares The Kavli Prize in Nanoscience with Ralph Nuzzo, David Allara and George Whitesides for discovering and applying an approach that’s been used in everything from batteries to car windshields, to dental implants. 

Scientific American Custom Media, in partnership with The Kavli Prize, spoke with Jacob to learn more about his contribution to this work.

———

Megan Hall: Jacob Sagiv knew he wanted to be a chemist since he was a kid.

Jacob Sagiv: I played chemistry since I was 10 years old. But of course, when you say chemistry, what do you think? You think about test tubes, boiling something, putting liquid from one beaker into another beaker. 

Hall: By the time he was in graduate school, Jacob had evolved from playing with test tubes to manipulating molecules.

Sagiv: The dream of chemistry is to have a handle on each molecule, to be able to put it in the right place, and to build with molecules. This is the ultimate goal that every chemist would dream about.  

Hall: So far, Jacob had tried out different ways of arranging molecules by dissolving them into thin plastic film. He found if he stretched this film, the molecules would line up and he could measure them.

Sagiv: It’s in a solid, which is a polymer, and you can have some control on how these molecules are organized by doing this, and this was useful.

Hall: But by the time Jacob finished his PhD, he was hungry to do more. And he needed a job.

Sagiv: I was looking for a postdoctoral position somewhere. And I had a friend, a colleague, who was also playing with molecules and polymers. On his desk, I suddenly saw a paper with some strange pictures.

Hall: These strange pictures were simple — just lines and circles. But they represented molecules being arranged into a single layer.

Sagiv: I never saw something like this, so I asked him, what is that? And he said, these are monolayers. I asked, what is that, and he started to explain it to me.

Hall: Jacob’s friend explained that these monolayers were formed by putting molecules in water. Not just any molecules — a specific kind with one end that’s attracted to water and one end that’s repelled by it.

Sagiv: So if you put them on water, they stick onto the water surface. But they do not dissolve, they don’t go into the water.

Hall: Imagine that these molecules look like matches, with a head that’s attracted to the water and a tail that’s not.

Sagiv: If you throw them on the table, they disperse randomly. If you put them in the box and bring them together, and they have no space to move, then they are aligned.

Hall: This is basically what the scientists did. They lined up all of these match-like molecules by carefully pushing on the surface of the water, until they were all standing straight up, but on their heads.

Sagiv: Then it’s like a carpet floating on water and all molecules are aligned.

Hall: Scientists could then scoop these molecular carpets out of the water using glass slides. They then formed layers that could change the way surfaces act.

Sagiv: And they showed very nice effects. For example, antireflective coatings. You can reduce the reflection of a surface and so on.

Hall: This process had been invented back in the late 1920s by Irving Langmuir and Katharine Blodgett.

Jacob had never read about their work before but when he saw that article on his friend’s desk, he was immediately hooked. 

Sagiv: I remember that I immediately knew that this is what I want to do. You know, it’s like falling in love.

Hall: He rushed to the library to learn more about this technique, and went on to join a lab led by Hans Kuhn, who was building off the technique that Langmuir and Blodgett had developed.   

Sagiv: They started, I think, in the early 60s playing with the Langmuir–Blodgett. And this, I would say, was the mecca of Langmuir–Blodgett at that time.

Hall: But there was a puzzle the lab couldn’t figure out.

Sagiv: They were asking themselves, how can we align the molecules within the Langmuir–Blodgett.

Hall: Scientists in the lab thought if you took a single layer of molecules and laid them on top of a surface covered in crystals, the molecules would fit into the pattern of those crystals. The problem was that the crystals they used dissolved in water.

Sagiv: So, in order to transfer the Langmuir–Blodgett, we have to dip it into the water. The moment we dip it in the water, the organization is lost.

Hall: To solve this problem, Jacob went back to his experience in graduate school, organizing molecules using thin polymer films.

Sagiv: I said, okay, I have a better idea. I know how to make polymers that are not soluble in water. And I know that molecules get oriented inside the polymer.

Hall: Jacob thought, if you put a Langmuir–Blodgett layer on top of a polymer film, you could organize the molecules.

Sagiv: And then I started playing with this.

Hall: But…

Sagiv: Nothing. The Langmuir–Blodgett monolayer doesn’t want to reorganize.

Hall: He tried to figure out why this didn’t work the way it had for him in graduate school.

Sagiv: So then I started thinking, just a moment, why they do not align? They don’t align because they’re stiff carpets. 

Hall: The Langmuir–Blodgett monolayers were created by pushing a lot of molecules together and now they were stuck.

Sagiv: They’re like a solid, the molecules cannot move.   

Hall: But Jacob saw this limitation as an opportunity.  

Sagiv: The best thing is experiments that do not work as predicted, because I think that our minds are limited to a certain kind of thinking, and the experiment can teach you more than you can think in advance.

Hall: If the Langmuir–Blodgett monolayers were too compressed to reorganize, what if you didn’t use them at all? If you put the right molecules into a solution, would they organize themselves? Jacob gave it a try.

Sagiv: I use just an organic solution, not water. I dissolved the molecules into the organic solution. I dipped a proper surface. And then immediately I got what I wanted. The molecules got aligned, and it was beautiful.

Hall: Jacob had just discovered that you don’t need physical pressure to create these monolayers. You could just use the natural interactions between the molecules and the surface.

Sagiv: But you have to know what to put there. I mean, this solution must be the right solution, under the right condition and the right molecules, and if everything is right, you just dip in and take it out.

Hall: These layers formed by chemical reactions, not physical pressure, would come to be called self-assembled monolayers. And they revolutionized our approach to manipulating molecules and coating surfaces. But at the lab, no one was interested in Jacob’s discovery.  

Sagiv: This is one of the problems when you start something new. It’s very difficult to get people to do something else.

Hall: Everyone else at the lab was comfortable using Langmuir–Blodgett monolayers and they didn’t want to change course. So, Jacob left and got a position at the Weizmann Institute of Science in Israel, where he published several papers on his discovery. 

But still, no one really noticed.

Sagiv: There was the first international conference on Langmuir–Blodgett films in 1982. I write them that I want to participate. And I’m getting a poster presentation, not a lecture.

Hall: Even his former mentor, Hans Kuhn, criticized Jacob’s self-assembled monolayers. He said they weren’t as good as the ones formed using the Langmuir–Blodgett technique. Jacob argued that this is often the case with new technology.

Sagiv: Take for example, the first airplane. Compare it to a hot air balloon. It was a superior principle, but it didn’t work as well. This doesn’t mean that we stay with the balloon forever.

Hall: But most academics were unconvinced. Even the scientists at Jacob’s own institution. He failed to get tenure at the Weizmann Institute and was forced to resign.  

Sagiv: And I went to the unemployment office in our town, Rehovot, and registered as a professor of chemistry, unemployed.

Hall: But slowly, Jacob’s luck changed. The Weizmann Institute of Science let him come back as an associate professor and reapply for tenure. 

Also, over in America, his fellow laureates Ralph Nuzzo, David Allara and George Whitesides had discovered his work. Nuzzo and Allara were also studying self-assembled monolayers at Bell Labs.

Sagiv: They invited me to visit them at Bell Labs. It was fantastic. And they told me what they are doing. And I told them what we’re doing.

Hall: The scientists at Bell labs cited Jacob in their research papers. In 1989, Jacob finally got tenure. He’s now widely known for his contributions to nanoscience and chemistry, but it took time. 

Hall: Jacob says the best science is always driven by pure curiosity. But that doesn’t always lead to success.

Sagiv: You will never get a grant stating that the aim of this work is to satisfy your curiosity. You always have to say what is this good for? But, if every time you think, what is this good for in terms of immediate application, you are not going to progress too much, in terms of basic science.

Hall: Jacob’s advice to other scientists? If you want a good career, don’t follow his path. If you want to make an important discovery, keep moving, in spite of the obstacles.

——

Hall: Jacob Sagiv is a professor at the Weizmann Institute of Science in Rehovot, Israel.

This year, he shared The Kavli Prize in Nanoscience with Ralph Nuzzo, David Allara and George Whitesides.

The Kavli Prize honors scientists for breakthroughs in astrophysics, nanoscience, and neuroscience — transforming our understanding of the big, the small and the complex. 

The Kavli Prize is a partnership among the Norwegian Academy of Science and Letters, the Norwegian Ministry of Education and Research, and the US-based Kavli Foundation. 

This work was produced by Scientific American Custom Media and made possible through the support of The Kavli Prize.

[The above text is a transcript of this podcast.]