Effect of Charge on Interfacial Activity and Micelle Formation of Ion-containing Block Copolymers at the Oil-Water Interface

Understanding the role of charge interactions in the self-assembly of ion-containing block copolymers continues to be a challenge, especially in systems such as partially quaternized polystyrene-block-poly(2-vinylpyridine) (PS-Q2VP) where multiple factors, such as ionic correlations, ion solvation, and Flory-Huggins interactions, are at play. Here, we present the results of a combined theory and experiments-based approach to investigate the effect of charge interactions on the micelle formation and interfacial activity of PS-Q2VP block copolymers at the oil-water interface. We use the SCFT-LS method to investigate the self-assembled morphologies of PS-Q2VP in solvents, to delineate the role of solvent quality and charge interactions on micelle morphology. We characterize the interfacial activity and micelle formation of PS-Q2VP via a combination of pendant drop measurements and x-ray scattering techniques and demonstrate that charge interactions can be a powerful tool in controlling the interfacial adsorption and self-assembly of PS-Q2VP block copolymers. These results represent a promising model system for understanding and utilizing the role of charge interactions on the phase behavior of ion-containing block copolymers using theory and experiments.