ABSTRACT
Polyelectrolyte-surfactant complexes (PSCs) have gained considerable interest in recent years both from a fundamental and from a practical/technological point of view [1-13]. In a similar fashion as block copolymers or microemulsions, these systems are able spontaneously to self-assemble into microphase-separated macrolattices with a high degree of long-range order on a supramolecular length scale. However, PSCs are distinguished from those former systems by the presence of strong electrostatic interactions which usually dominate their structure and property relationships. Polymer chain entropy contributions or weak enthalpic Flory-Huggins-type interactions play a far less prominent role than they do for noncharged systems. A microphase separation into hydrophilic (charged polyelectrolyte backbone, charged surfactant head groups, aqueous solvent with surfactant counter ions) and hydrophobic (aliphatic surfactant chains, neutralized ion-paired hydrophobic backbone) domains shows a considerably higher degree of phase segregation (superstrong segregation regime in [14, 15]) with a much narrower interface between the domains than found, for example, between non-charged polymer melts. The introduction of long-range electrostatic interactions leads to a much broader variety in the phase behavior of the PSCs. Note also that the electrostatic interactions can be fine tuned by adjusting the charge density of the polyelectrolytes. A broad variety of highly ordered and highly symmetrical morphologies has been found, many of which are not observed in classic systems.
