Researchers at Cornell University have developed a new all-dry polymerization technique that uses reactive vapors to create thin films with enhanced properties, such as mechanical strength, kinetics and morphology.
The synthesis process is gentler on the environment than traditional high-temperature or solution-based manufacturing and could lead to improved polymer coatings for microelectronics, advanced batteries and therapeutics.
“This scalable technique of initiated chemical vapor deposition polymerization allows us to make new materials, without redesigning or revamping the whole chemistry. We just simply add an ‘active’ solvent,” said Rong Yang, assistant professor in the Smith School of Chemical and Biomolecular Engineering in Cornell Engineering. “It’s a little bit like a Lego. You team up with a new connecting piece. There’s a ton you can build now that you couldn’t do before.”
The solvent in this case interacted with a common CVD monomer via hydrogen-bonding.
“It is a novel mechanism, although the concept is simple and elegant,” lead author doctoral student Pengyu Chen said. “Building on this interesting strategy, we are developing a robust and generalizable science of solvation engineering.”
Yang collaborated on the project with Jingjie Yeo, assistant professor in the Sibley School of Mechanical and Aerospace Engineering, and Shefford Baker, associate professor of materials science and engineering. The group’s paper, “Engineering Solvation in Initiated Chemical Vapour Deposition for Control over Polymerization Kinetics and Material Properties,” was published Feb. 9 in Nature Synthesis.
She and Chen sought to develop a different approach to diversify CVD polymers by borrowing a concept from conventional solutions synthesis: the use of a “magic” solvent; an inert vapor molecule, that isn’t incorporated into the final material, but instead interacts with a precursor in a way that produces new material properties at room temperature. “It’s an old chemistry but with new features,” Yang said.
“We distinguished the effects of different solvents at the molecular scale and we clearly observed which solvent molecules were more inclined to bind with the monomer,” Yeo said. “Thus, we can eventually screen which Lego pieces will be able to fit best with each other.”
“This adds a new dimension to materials design. You can imagine all kinds of solvents that could form hydrogen-bonding with the monomer and manipulate the reaction kinetics differently. Or you can have solvent molecules incorporated into your material permanently, if you design the molecular interaction correctly,” Yang said. “There’s so much to explore with this added degree of freedom going forward.”
