Observation of Nano-Sized Spherical Polyelectrolyte Brushes By Small Angle X-Ray Scattering

Small angle X-ray scattering (SAXS) is a well-established characterization method in materials science and colloidal physics. SAXS is highly valuable for a comprehensive analysis of polymer colloids, and can give information on the radial structure of nanoparticles. Spherical polyelectrolyte brush (SPB) is a nano-sized core-shell particle with a polymer core densely grafted by linear polyelectrolyte chains, which has been synthesized by photo-emulsion polymerization. SPB can be used to create a large well-defined surface in an aqueous environment, which is suitable for the in-situ preparation of metal nano-particles or immobilization of proteins. The SPBs were observed by SAXS, and the scattering data were analyzed by two new methods, which can reflect an apparent core-shell pattern as well as the interaction among SPB. The particle size change upon changing pH and salt concentration of the solution as observed by SAXS agreed well with the observation by dynamic light scattering (DLS). SAXS can also determine the change of SPB by immobilzation of metal nanoparticles or adsorption of proteins.