Cooperation with Germany: Studies of Polyelectrolyte Brushes in Confined Environments

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In this project funded by the Macromolecular, Supramolecular and Nanochemistry Program of the Chemistry Division, Christopher Ober of Cornell University will study the physical chemistry of polyelectrolyte brushes. This work includes an international collaboration with Prof. Jurgen Ruhe of the University of Freiburg, Germany. Prof. Ruhe's work will be funded by the Deutsche Forschungsgemeinschaft (DFG). Polyelectrolyte brushes are of particular interest because they feature both confinement, which forces the polymer chains into a largely stretched conformation, and the presence of charges along the polymer backbones. The international team will investigate how the swelling of polyelectrolyte brushes scales with the size of a nanostructure produced using advanced lithography and how the system transitions from swelling of a two-dimensional pattern into swelling of a three-dimensional structure. Furthermore, the team will characterize the effects of brush height, charge and density on interactions with soluble species and establish what are promising strategies to stabilize polyelectrolyte brush structures and prevent "entropic death," that is the entropy induced breakage of chains from the brush surface. The broader impacts involve active international exchanges exposing graduate students and associated undergraduate researchers to a global research partnership. Additionally, summer schools will be hosted on specific topics that enable a deeper consideration of the types of problems encountered in the study of polymer brushes.Polymers are long chain organic molecules and are found in many facets of everyday life that utilize plastics, including food packaging, structural materials for automotive and aerospace transportation, and lightweight electronic devices. Nature uses charged polymer films at interfaces to control lubrication, to limit biofouling, and to aid in keeping surfaces wet. This research seeks to develop and understand stable, sustainable surface structures that undergo controlled interactions with soluble, synthetic or biological materials. Through development of new chemical components and process strategies, this research could lead to better materials for biomedical devices, environmental and medical sensors, and environmentally friendly coatings.