(241a) Interactions and Complexation in Polyelectrolyte-Nanoparticle Systems (Invited Talk)

Polyelectrolyte (PE)-protein and PE-particle mixtures form an important class of systems in which their phase behavior and complexation characteristics play a crucial role in influencing their properties. Despite the practical importance of PE-particle mixtures, the parameters governing the interactions and their phase behavior characteristics have had much less theoretical work compared to their neutral counterparts. Recently, we have developed two pronged approach which allows us to study the effective interactions and the phase behavior in mixtures of charged nanoparticles (CNP) and polyelectrolytes (PE). On the one hand, we have adapted polymer self-consistent field theory approach to study the hierarchy of the two-, three- and multi-body interactions between CNP's. We have found that for the strong PE's and in the absence of polarization interactions, the CNP-CNP interactions are essentially pairwise and involves an interplay of depletion attraction and electrostatic repulsions. We have also analyzed of weak PE's and the presence of polarization interaction. In such systems, CNP's interactions remain qualitatively similar to the above systems, but the multi-body interactions appears to be significantly enhanced. To study the phase behavior of such systems, we have adapted the single chain in mean-field simulation approach to effect a multibody simulation of the PE-CNP systems. Using such an approach, we study the phase behavior and complexation characteristics in a variety of systems.