Diblock Copolymer Micelles with Ionic Amphiphilic Corona

Summary: Aqueous dispersions of diblock copolymer micelles with homogeneous hydrophobic core (polystyrene) and heterogeneous amphiphilic corona from ionic N-ethyl-4-vinylpyridinium bromide (EVP) and hydrophobic 4-vinylpyridine (4VP) units have been prepared at pH 9. The structure and dispersion stability of micelles as function of the ratio and distribution pattern of ionic and hydrophobic units in corona have been systematically studied by means of transmission electron microscopy, static and dynamic light scattering, UV-spectrophotometry techniques. It was shown that gradual decrease of the quantity of EVP-units in corona had no impact on micelle structure until its fraction was above 0.7. When EVP-fraction dropped below this point noticeable changes in micelle mass and dimensions were observed. In the case of random distribution of 4VP and EVP units these changes were moderate in value and jump-like in character. In the case of mictoarm (starlike) distribution of 4VP and EVP blocks changes were large in value and monotonous in character. The presented results may be of certain use for design of polymer micelles with nanosegregated corona.