For Work With Polymers, Mingjiang Zhong Wins CAREER Award

For his work in developing a new polymer that could be used for biomedical applications as well as water filtration, Mingjiang Zhong has won a 2019 Faculty Early Career Development CAREER Award from the National Science Foundation (NSF).

Zhong, an assistant professor of chemical & environmental engineering, is using the $687,110, five-year award to focus on polymers with branched structures - a property that gives them numerous potential applications. Polymers, which are made of repeated chains of molecules to make a larger molecule, bear different structures. While some have linear chains, others have branched structures, in which side chains of molecules branch off from the “backbone” of the polymer, creating a brush-like structure.

Zhong is developing polymers with branches, or side chains, that bear their own branches.

“It’s a new synthetic method that enables us to develop novel polymeric structures,” Zhong said. A polymer structure with a higher degree of branching means that it has a greater density without taking up more room. “It enables higher density per unit of volume - it’s highly compact. They occupy the same volume, but this one has up to 10,000 times the functionality.”

Zhong has honed his method so that he can control the degree of branching. He can structure the polymers in a way similar to aggrecans, proteins that serve as a critical component for cartilage structure and the function of joints. That means it could potentially be used for drug delivery systems or as a precursor for artificial tissue.

“If you have injuries or wounds that need new tissue, not only does it have to be biocompatible in terms of chemical function, it also requires mechanical compatibility,” he said.

And as the demand for ever-smaller electronics continues, the polymer’s combination of high-functionality and low-volume makes it a promising candidate for usage in nanoelectronics fabrication.

Zhong is also working with Menachem Elimelech, the Roberto C. Goizueta Professor of Chemical & Environmental Engineering, on using his polymers for water filtration. Since water and salt molecules are about the same size, it’s difficult to develop a membrane that mechanically filters out the salt. However, Zhong is developing a polymer-modified membrane that would chemically select the salt out of the water that passes.

“These chemical groups don’t like salt - only water - so they allow the passing of water but not salt,” he said. And the additional branching would allow for even more selective filtration without requiring thicker modification on the membrane surface. “You want selectivity, but don’t want to sacrifice permeability. So if we can graft branched polymers, this kind of structure occupies a lot of membrane surface without occupying more volume in transport channels. You still allow water to go through, but it rejects the things you don’t want.”