Interactions between Polymers and Nanoparticles : Formation of Supermicellar Hybrid Aggregates

TL;DR

This paper investigates the formation and properties of stable supermicellar hybrid aggregates composed of yttrium-based inorganic nanoparticles and polyelectrolyte-neutral block copolymers, highlighting their structural features and stability.

Contribution

It provides new insights into the structural properties and formation mechanisms of inorganic-organic hybrid aggregates using light scattering techniques.

Findings

Hybrid aggregates exhibit core-shell structures.

Size and aggregation numbers depend on mixing conditions.

Aggregates show remarkable stability.

Abstract

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