Polyelectrolyte brushes

Polyelectrolyte brushes constitute a new class of material which has recently received considerable interest. The strong segment-segment repulsions and the electrostatic interactions present in such systems bring about completely new physical properties of such monolayers compared to those consisting of either non-stretched or non-charged polymer chains. in this review some recent progress on the theory, synthesis, and swelling behavior of polyelectrolyte brush systems in different environments is discussed. The height of the polyelectrolyte brushes is studied as a function of the molecular weight and graft density on both planar and spherical surfaces. In addition it is elucidated how the brushes are affected by external conditions such as the ionic strength of the surrounding medium, the presence of multivalent or polymeric ions and in some cases by the pH of the contacting solution. Two more specific cases, the synthesis and characterization of mixed polyelectrolyte brushes and cylindrical polyelectrolyte brushes, in which charged polymer chains are attached to the backbone of other polymers, are described in more detail.