Interpolyelectrolyte Complexes Based on Polyionic Species of Branched Topology - Self Organized Nanostructures of Amphiphilic Block Copolymers - page 156

co-assemblies via polyion interchange reactions [ 95 ] . Thus, the observed trend can
be reasonably explained, as for the polyion interchange reactions discussed above.

5 Conclusions

The results of experimental and theoretical research on water-soluble (nonstoichio-
metric) IPECs based on nonlinear (branched) polyionic species (HPE) complexed
with oppositely charged linear PEs (GPE) demonstrated that the main feature of
such macromolecular co-assemblies is their pronounced compartmentalized struc-
ture, which results from a distinctly nonuniform distribution of the linear GPE
chains within the intramolecular volume of the branched HPE. In the case of star-
shaped PEs or star-like micelles of ionic amphiphilic block copolymers, this com-
partmentalization leads to the formation of water-soluble IPECs with core-corona
(complex coacervate core) or core-shell-corona (complex coacervate shell) struc-
tures, respectively. Water-soluble IPECs based on cylindrical PE brushes appear to
exhibit longitudinally undulating structures (necklace) of complex coacervate pearls
decorated by the cylindrical PE corona.
An important inherent feature of IPECs comprising branched HPEs is the in-
tramolecular segregation of its branches: a certain fraction of the branches whose
charge is compensated by chains of the linear GPE is nearly completely embedded
into the complex coacervate domains, whereas other branches that are virtually free
of linear GPE chains form the hydrated corona.
Finally, the enormous number of possible combinations of oppositely charged
polymeric components that can be involved in interpolyelectrolyte complexation
offers attractive perspectives for the preparation of water-soluble multicompartment
nanosized macromolecular co-assemblies with desired properties. We believe that
such novel IPECs are very promising and will be in demand for their future ap-
plications in nanomedicine (e.g., gene and drug delivery, and diagnostic systems),
biotechnology, and nanotechnology as nanocontainers, nanoreactors, and molecular
templates for nanoelectronic devices.

Acknowledgments Support from the EU Marie Curie Research and Training Network “Self-
Organized Nanostructures of Amphiphilic Copolymers” (POLYAMPHI) (project MCRTN-CT-
2003-505027), the Deutsche Forschungsgemeinschaft, and the Russian Foundation for Basic
Research (projects nos. 03-03-32511-a, 06-03-32696-a, 08-03-00336-a, 09-03-00851-a) is grate-
fully acknowledged. Dr. F. Schacher (Friedrich-Schiller-Universität Jena, Germany) and Dr. S.V.
Larin (Institute of Macromolecular Compounds, Russian Academy of Sciences, St. Petersburg,
Russia) are gratefully acknowledged for their help with preparation of the figures.