Formation and characterization of covalently bound polyelectrolyte brushes

Abstract

Poly(4-vinylpyridine) (PVP), functionalized at one terminus with a styrenyl group, was end-grafted to vinyl-functionalized self-assembled monolayers by UV irradiation in 1-methyl-2-pyrrolidinone. In this solvent and with oxygen excluded, surface reactions appeared to be selectively limited to the polymer terminus. The dry film thickness was determined by ellipsometry and the grafted amount by FTIR-ATR (Fourier transform infrared spectroscopy in attenuated total reflection). Controlled amounts of positive charge were introduced into the grafted chains by alkylation with a 2.5% solution of CH3I in dimethylformamide (DMF). FTIR-ATR was used to quantify the extent of alkylation, from 10% to 96%. These polyelectrolyte brushes will comprise a model system for studying polyelectrolytes at surfaces.