Nanoscopic polymer particles with a well-defined surface: Synthesis, characterization, and properties

We review our recent work on polymeric latex particles having a well-defined surface of grafted polymers. Two types of particles are discussed i) particulars with a thermosensitive shell, and ii) particulars bearing a dense layer of linear polyelectrolyte chains on their surface ("spherical polyelectrolyte brush"). Both types of particulars consist of a polystyrene core onto which either linear or crosslinked chains are grafted. The synthesis of these core-shell particles proceeds in a two-step process which is reviewed in detail. In particular, we discuss the photo-emulsion polymerization used for the synthesis of the spherical polyelectrolyte brushes. Most of the studies of these particles have been done in aqueous suspension. Here the equilibrium structure of the surface layer of the particles has been investigated by dynamic light-scattering and by small-angle X-ray scattering. Results deduced from the flow behaviour of the particles in dilute solution can directly be derived from static data. Very recent data refer to the interaction of the spherical polyelectrolyte brushes with solid interfaces. It is demonstrated that particles bearing positively charged polyelectrolyte chains interact strongly with negatively charged surfaces. The strong interaction that is directly evident from AFM studies can be used to generate 2D networks of the particles on the surface.