Polyelectrolyte micellar complexes*

Polyelectrolyte complexation opens new territory for polymer self-assembly. Micelles with complex cores are formed from neutral-charged block copolymers complexing with oppositely charged homopolymers and copolymers. The resulting objects bear a physical resemblance to micelles formed from solvophobic self-assembly of block copolymers. However, the details of formation, exchange, dissociation and scalling laws are all different. These characteristics will be discussed. The cores of these micelles can be used as depots and delivery vehicles for oppositely charged macromolecules. When these macromolecules are biologically active, such as proteins and nucleic acids, polyelectrolyte complex micelles can be used as therapeutic delivery vehicles. We have studied such micelles with nucleic acid-containing cores in detail with some unexpected results. At high concentrations of these micelles, when they begin to impinge on one another, they form as series of ordered phases with varying strucutures from bcc to hexagonal to lamellar. This set of structures and their associated properties will be discussed at length.