May 6, 2017 at 10:39 pm

Cimatu: Toying with Molecular Interfaces

Dr. Katherine Cimatu in her lab in Clippinger Hall.

Dr. Katherine Cimatu in her lab in Clippinger Hall.

By Amanda Biederman
NQPI editorial intern

Ohio University NQPI member Dr. Katherine Cimatu, Assistant Professor of Chemistry & Biochemistry, recently published a series of papers in the Journal of Physical Chemistry C describing the roles of various functional groups in the molecular conformation of monomers and polymers at different interfaces.

Polymer coatings and inhibitors have many commercial applications including prevention of pipeline corrosion and prevention of biofilm formation.

Cimatu’s group uses sum-frequency generation (SFG) to characterize methacrylate-based functional monomers and polymers at the air-liquid (for monomers), solid-liquid, and air-solid (for polymers) interfaces. Chemical structure influences the orientation and conformation of monomeric and polymeric molecules at the bulk and interface.

“SFG is very interface-specific,” Cimatu said. “We isolate the consequences of the change in the chemical structure from the bulk to the interface.”

First, the group characterized the influence of three substituents on monomer- and polymer-air interfaces: hydroxy-, as a reference; chloro-, for halide/electronic effects; and phenoxy-, for steric (bulk) effects. They found that substitution at the ethyl group affected the functional monomer conformation. In contrast, the alkene-methyl group was not present in the polymer film.

Using polarization combination analysis and mapping, they calculated the degree of ordering in the specific monomer 2-methoxyethyl methacrylate. The monomer was oriented and partially ordered, with varying substituents such as methoxy-, methylene-, methyl- and alkene-methylene groups at the interface. Cimatu said she understands more fully the interfacial properties of this monomer.

Finally, they addressed the effects of four bulky substituents: methoxy-, phenoxy-, isopropoxy- and tert-butoxy- methacrylatebased functional monomers. These groups affected the number density of less bulky ones, allowing the bulky substituents to orient themselves toward the interface.

Cimatu is collaborating with OHIO Chemical and Biomolecular Engineering professors Srdjan Nesic, Marc Singer, Sumit Sharma and David Young to study corrosion inhibitors on steel surfaces through OHIO’s Institute for Corrosion and Multiphase Technology. Additionally, Cimatu collaborates with Chemistry & Biochemistry professor and NQPI member Dr. Jixin Chen to study perovskite materials used in solar cells.

“What we’re doing right now with these functional monomers is just models to fully understand how these multi-functional and complex small molecules behave at different interfaces,” Cimatu said. “But with this new knowledge, hopefully, we can design more monomers and create polymers that will be applicable as coatings and inhibitors.”

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