Biomacromolecules, Vol.7, No.10, 2890-2900, 2006
Macromolecular assemblies based on coupled inclusion complex and electrostatic interactions
Macromolecular assemblies are elaborated by mixing beta-cyclodextrin-containing polymer (poly beta CD), dextran sulfate polyanion (NaDxS), and cationic amphiphiles which are adamantane derivatives (Ada1 or Ada2) in aqueous medium. These components are assembled via coupled inclusion complex interactions (adamantyl group with cyclodextrin cavity) and electrostatic attractive interactions (positive charges of Ada with negative charge of NaDxS). The structural properties are studied by viscometry and small angle neutron scattering. Ternary aggregates with larger size and lower compacities are observed as the cation concentration is increased, until phase separation occurs. The results are in good agreement with a core-shell association mechanism, the core being made of one poly beta CD chain, the shell of NaDxS chains, and the Ada amphiphiles being distributed more or less homogeneously inside the cyclodextrin cavities. The nature of the Ada counterions has a strong influence on the association as Ada1 with I- counterions give smaller and less compact aggregates than Ada2 with Br- counterions.