The Role of Host - Guest Interaction in Thickening and Phase Separation of B-Cyclodextrin Polymer and Polymers Bearing Cyclic Hydrophobic Side Groups

Abstract

A large variety of architectures can be obtained from macromolecular assemblies involving inclusion complexes between polymers in aqueous solutions. Mixtures of hydrophically end-capped PEO with ß-cyclodextrin polymers have already been described in previous papers [1 – 3]. It was shown that the hydrophobic moieties were interacting by host-guest association with the ß-cyclodextrin cavities and this was at the origin at the formation of intermolecular aggregates. The strength of the interaction between the two polymers appeared to be mostly determined by the number of hydrophobe per PEO chain. In the present paper, the hydrophobic molar ratio has been varied by using “star” PEO of constant arm size (5000) but different number of arms (3, 4, 8). The PEO stars were terminated with adamantyl end groups which are known to make very stable complexes with ß-cyclodextrin [4]. The ß-cyclodextrin polymers (ß-CD/EP) are formed by polycondensation with epichlorohydrin under strongly alkaline conditions [5]. High molecular weights but water soluble polymers were obtained by conducting the reaction close to the gelation threshold.