Formation of Interpolyelectrolyte Complexes (IPECs) between Double-Hydrophilic Block Copolymers and Polysoaps: The Role of Hydrophobic Modification and Mixing Ratio as Structural Control Parameters

The formation of interpolyelectrolyte complexes (IPECs) by mixing oppositely charged polyelectrolytes has been studied extensively over the last few years. In this article, we show how the structure of IPECs formed by a double-hydrophilic anionic block copolymer and hydrophobically modified poly (2-(dimethylamino)ethyl methacrylate) (PDMAEMA) is affected by the mixing ratio and the type and quantity of hydrophobic modifications of the PDMAEMA. Static and dynamic light scattering as well as small-angle neutron scattering (SANS) reveal the role of hydrophobic modifications on large-scale aggregation behavior. Modeling SANS data with a cluster of hydrated spheres formed by the polymeric species enabled us to see that the aggregates become less hydrated upon switching from polycation to polyanion excess, and larger and more well-defined aggregates are formed with hydrophobically modified PDMAEMA.