The plastics of everyday life -- polystyrene cups, polypropylene sport clothing, polyethylene bottles -- begin as a collection of small, identical units of a molecule. Then hundreds of those units, or monomers, are strung together into polymers "like pearls on a necklace," as Brookhart explained. How that happens is where he comes in.
"One way I like to describe what I do is to study how a single metal atom such as nickel or palladium can stitch together molecules in various ways to form chains," said Brookhart, a professor of chemistry at the University of North Carolina, Chapel Hill.
Without metal atoms, polymers would not form. The trick is to control the metal atoms' chemical environment, and thus their reactivity, to tailor-make the properties of the polymer, he said.
For example, Brookhart's research team has made new polymers by constructing metal catalysts -- chemistry's construction workers -- that insert monomers in the middle of chains rather than at the end: "Instead of a linear chain, we can get a branched one," he said. The difference in properties can be remarkable: the stiff, linear polypropylene of milk jugs versus the pliable, branched polypropylene of garbage bags, for instance.
His particular achievement is discovering ways to use unconventional metals that string monomers together in different ways. "This gives us a broader range of polymers," he said, adding several have been licensed by the chemical company DuPont for possible commercialization.
Brookhart described himself growing up as "a chemistry-set kid" who liked to build rockets. "Those were the days when you could go down to the drug store and buy everything you need to make rocket fuel," he remembered.
Brookhart received his undergraduate degree from Johns Hopkins University in 1964 and his Ph.D. from the University of California, Los Angeles, in 1968. He is a member of the ACS divisions of organic, inorganic and polymer chemistry.
The ACS Award in Polymer Chemistry is sponsored by ExxonMobil Chemical Co.