Studies of Catch and Release Behavior of Polyelectrolyte Brushes

Cornell University, Ithaca NY

Investigators

Abstract

With the support of the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry (CHE) and the Polymers Program in the Division of Materials Research (DMR), Professor Christopher K. Ober of Cornell University will prepare and study model polymer brushes with carefully tailored capture-release properties. Polymer brushes are surface coatings made by growing individual polymer macromolecules from a surface and possess properties that can change over only a few nanometers from glass-like (a hard substrate) to tissue like (a soft, wet surface). Brushes make ideal materials as sampling systems for biological or environmental applications due to their large surface area. By capturing a target molecule we will concentrate to detect even small amounts of a chemical or biomolecule, and then once done, trigger release of the captured targets to enable reuse of our device. The goal is to understand the capture-release process to make resuable and more efficient sampling and detection systems. Characterization of these brush surfaces will include study of the capture-release mechanism as a function of brush architecture and binding site location and spacing on these new brushes. In these studies scientists in Germany and the United Kingdom will aid in characterizing the process and structure of these active polymer brushes. This work will offer a substantial training opportunity for students in Ithaca, New York that represents a cross-pollination between polymer chemistry and materials science while enabling them to take part in international collaborations and exchanges. Undergraduate researchers will work with the exchange partners to make and to study these materials. Outreach activities will include demonstrations designed for and made to high school teachers in teacher workshops of the value of nanochemistry in environmental and biological studies. This research is focused on the preparation and study of capture-release coil polymer brushes that have varying levels of binding sites with selected spacing along the backbone and in different positions of the side. Controlled radical polymerization will be used to create tailored narrow dispersity brushes in a single strand or bottle brush architecture based on acrylamide and styrene-maleimide polymers and peptoid precision synthesis will be employed to make brush side arms that enable precise placement of active sites. Alternating copolymerization will also space out binding sites and associated packing stress along the backbone and spacers will separate those sites from the backbone, both intended to maximize packing potential and control binding site distribution in the brushes. Different brush designs will be tested for capture-release applications through our Freiburg collaborators. Advanced characterization of the brushes will be made using analytical methods ranging from neutron reflectivity and GISAXS to fluorescence and QCM studies of brushes exposed to different binding systems. The research has a potential to highly impact the technological features such as selective binding, capture and release, grafted brush stability, and antifouling applications. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.