December 1, 2015

THE SCIENTIST | Prof. William Dichtel Discusses New Uses for Covalent Organic Frameworks

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It was 1995, and a young William Dichtel had finished taking all the science classes available in his small high school in Roanoke, Virginia. His chemistry teacher, who happened to have a Ph.D., tutored the budding scientist in organic chemistry.

“I went to college, took more classes in chemistry, and the rest is history,” Dichtel says.

Today, Prof. William Dichtel, chemistry, studies how to build new organic materials that may have promising use in our daily lives, from more efficient batteries to highly sensitive explosive detectors. Apart from research, he also teaches organic chemistry and is involved in efforts to improve undergraduate science education. In September, Dichtel received a MacArthur Genius Award for his research — a fellowship that comes with an annual $625,000 stipend for five years.

Dichtel’s research focuses on organic structures called covalent organic frameworks. Whereas most polymers are chains of organic molecules, much like beads on a string, COFs are more complex, being two- or three-dimensional.

“Covalent organic frameworks represent a new way of organizing matter,” Dichtel said. “Because they are so different from more typical polymers, they have a lot of promising applications that haven’t been tapped yet.”

Research on using COFs to make devices has traditionally been limited because they are naturally found as powders that do not dissolve in solution, making them difficult to use in creating devices such as batteries. One of Dichtel’s students, John Colson Ph.D. ’13, proposed using graphene, a two-dimensional sheet made of only carbon atoms, that would allow the COF to spontaneously grow, “right on the surface where we wanted it to,” Dichtel said.

“That was the first time anyone had done that before,” Dichtel said.

Overcoming this hurdle allowed research to progress to the point where, today, the Dichtel research group is creating test-batteries that contain the surface area of an ice hockey rink in the interior of a material that weighs as much as a dollar bill. The amount of charge these materials store is, in part, proportional to their surface areas. This makes Dichtel’s batteries extremely efficient at storing charge, especially as they can be charged and discharged in seconds.

Another application of Dichtel’s research has been in the area of sensing hard-to-detect explosives, such as RDX.

“I had a student, Deepti Gopalakrishnan Ph.D. ’14, working on a material for a different application who got to talking with another student, Jenny Novotney Ph.D. ’14, who was working on explosive detection, and it turned out that a material originally intended for something else was the best explosives detector we had ever seen,” Dichtel said.

Dichtel credits much of his research success to the accomplishments of his students.

“I work with an incredibly talented team of students who are very passionate about what they do,” Dichtel said, “We are constantly trying to push the limits of what has been done by humankind, and while it’s hard, every now and then we discover things that are really mind-blowing.”