Precise Control of Nanoparticle/Polyelectrolyte Brush Interactions by Tuning the Polymer Charge Fraction

Controlling the interactions between nanoparticles and surfaces in complex media is crucial to realizing a variety of nanoparticle-based applications reliant on tuning nanoparticle transport and diffusion. Creating a weak polyelectrolyte brush is a promising technique to control the nanoparticle/polymer brush interactions by tuning the pH. However, it is challenging to precisely control their interactions due to the sharp transition of the polymer brush properties with pH. In this study, we demonstrate that the nanoparticle/polymer brush interactions can be effectively and finely controlled by adjusting the polymer charge fraction. To control the charge fraction, quaternization of polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) was performed with 1-bromoethane (1-BE). FT-IR and NMR spectroscopy demonstrated that the charge fraction was readily tuned by adjusting the stoichiometric ratio between the monomer concentration of P2VP blocks and 1-BE. The quaternized P2VP brushes with various charge fractions were prepared using quaternized PS-b-P2VP. Quartz crystal microbalance with dissipation monitored the nanoparticle adsorption and desorption dynamics as a function of charge fraction and demonstrated that the nanoparticle/polymer brush interactions were controlled. This precise control of their interactions suggests potential applications of the quaternized P2VP brush for functional devices that adsorb and desorb nanoparticles.