EPR study of nitroxide-labeled brush polymers

Abstract

Bottle-brush polymers are highly branched polymers, which possess a high d. of polymer side chains uniformly grafted to the backbone of a linear polymer. Functional groups can be attached to different domains of the bottle-brush polymers for potential applications that range from nanomedicine to mol. electronics. We are interested in how the locations that the functional groups are placed in bottle-brush polymers affect their reactivities and interactions with surrounding environment. The results of the study will impact further development of bottle-brush materials as nanoscaffolds for biol. applications.We synthesized bottle-brush polymers with nitroxide probes covalently attached to variable locations of the polymers: backbone middle, backbone end and side-chain end etc. Electron paramagnetic resonanse (EPR) spectroscopy was used to study spin dynamics of the nitroxide probes. Parameters extd. from EPR spectra clearly indicate that the spin mobility is greatly influenced by the d. of near brushes of the polymer. The results are further confirmed by a redox reaction that shows different reactivities at different locations that the probe was attached.