Multi-morphological self-assembled structures in water of a biodegradable β-cyclodextrin-based copolymer

A rigid-coil β-cyclodextrin-poly (ɛ-caprolactone) (CD-PCL) copolymer was synthesized in which biodegradable flexible multi PCL arms were selectively connected onto the wide side of the rigid torus-shaped β-CD through ring-opening polymerization (ROP) of ɛ-caprolactone (CL) and protection/deprotection technique of β-cyclodextrin (β-CD) via trimethylsilyl groups. (1)H NMR, FT-IR, and GPC analysis confirmed the "jellyfish-like" branched architecture of CD-PCL copolymers. The self-assembled structures in water of the amphiphilic CD-PCL copolymer were investigated by transmission electron microscopy (TEM), dynamic light scattering (DLC) and viscometry. The results showed that CD-PCL could self-assemble into multi-morphological aggregates such as spheres, rods, vesicles, vesicular clusters and vesicular network in water. Interestingly, hierarchical stripe structure was observed in the formed vesicular network, which was driven by the crystallization of PCL segment in micelles. Moreover, the inclusion ability of copolymer micelles with ferrocenecarboxylic acid was investigated by UV.