Phase behavior and structure of polyelectrolyte-nanoparticle complex assemblies

Numerous examples of complex assemblies comprising oppositely charged polyelectrolytes and nanoparticles (or proteins) in aqueous environments exist in natural and synthetic systems. The structure and stability of these complex assemblies are dictated by numerous factors including solution conditions as well as polyelectrolyte and nanoparticle properties and are far from being fundamentally understood and controlled. In this work, we examine the effect of polyelectrolyte and nanoparticle concentrations, polyelectrolyte size, flexibility, charge density and degree of ionization, nanoparticle size and effective charge density and the pH and ionic strength of the solution on the structure and phase behavior of model nanoparticle-polyelectrolyte complex assemblies comprising negatively charged silica nanoparticles and diverse polycations. Conditions that lead to destabilization and phase separation of the complexes will be identified through turbidimetric and light scattering studies. Furthermore, X-ray and light scattering investigations on the structure and morphology of phase separated and the “soluble” stable complexes will be presented.