Interactions Between Polymers and Nanoparticles: Formation of “Supermicellar” Hybrid Aggregates

Abstract

When polyelectrolyte-neutral block copolymers are mixed in solutions to\noppositely charged species (e.g. surfactant micelles, macromolecules, proteins\netc), there is the formation of stable supermicellar aggregates combining both\ncomponents. The resulting colloidal complexes exhibit a core-shell structure\nand the mechanism yielding to their formation is electrostatic self-assembly.\nIn this contribution, we report on the structural properties of supermicellar\naggregates made from yttrium-based inorganic nanoparticles (radius 2 nm) and\npolyelectrolyte-neutral block copolymers in aqueous solutions. The yttrium\nhydroxyacetate particles were chosen as a model system for inorganic colloids,\nand also for their use in industrial applications as precursors for ceramic and\nopto-electronic materials. The copolymers placed under scrutiny are the water\nsoluble and asymmetric poly(sodium acrylate)poly(acrylamide) diblocks. Using\nstatic and dynamical light scattering experiments, we demonstrate the analogy\nbetween surfactant micelles and nanoparticles in the complexation phenomenon\nwith oppositely charged polymers. We also determine the sizes and the\naggregation numbers of the hybrid organic-inorganic complexes. Several\nadditional properties are discussed, such as the remarkable stability of the\nhybrid aggregates and the dependence of their sizes on the mixing conditions.\n