Synthesis of Spherical Polyelectrolyte Brushes by Thermo-controlled Emulsion Polymerization.

A novel method of thermo-controlled emulsion polymerization has been employed to synthesize spherical polyelectrolyte brushes that consist of a solid polystyrene core and a poly (acrylic acid) (PAA) shell covalently attached on the core surface densely by one end. The growth of brushes from the core surface was monitored by dynamic light scattering (DLS). The particle size of PS core latex showed a narrow size distribution when observed by scanning electron microscopy (SEM). The brush size changed significantly upon changing pH value and ionic strength, and displayed similar behavior to brushes prepared by photo-emulsion polymerization. The grafting density of the PAA brush, which was determined by cutting off the PAA chains using alkali hydrolysis, confirmed the formation of PAA brushes.