(24a) Manipulation of Dynamic Macromolecular Assemblies

The complexation of polyelectrolytes is well known to lead to interesting properties that have relevance in applications ranging from electrochemical applications to biomaterials systems.  Alternating layer-by-layer adsorption of polyelectrolytes in which complementary charge or hydrogen bonding groups are assembled can be manipulated through changes in effective ionic charge introduced following film construction to yield responsive thin film materials that can undergo dramatic changes in morphology, thickness, and overall stability with small shifts in pH, ionic strength, or even applied electrochemical potential.   Furthermore, LbL systems and their final structure are highly sensitive to differences in processing; changes in LbL film structure with rapid spray layer-by-layer assembly versus equilibrium solution adsorption in dipping baths can result in interesting kinetic trapping effects that alter film composition and performance, and can be manipulated to generate unique film morphologies.   Finally, the introduction of new functionalizable synthetic polypeptides as well as existing natural polymers can contribute to the unique properties achieved in these polymer systems.   The dynamic behavior observed in thin film systems can be translated to macromolecular assembly behavior in dilute solution through the manipulation of degree of ionization in self-assembled systems.