Self-assembly of polyrotaxanes synthesized via click chemistry of azido-endcapped PNIPAAm-b-pluronic F68-b-PNIPAAm/γ-CD with propargylamine-substituted β-CDs

A kind of γ-(cyclodextrin) (γ-CD)-based polyrotaxane (PR) is synthesized via an aqueous click reaction between propargylamine-substituted β-CD and polypseudorotaxanes (PPRs) self-assembled from azido-endcapped PNIPAAm-b-Pluronic F68-b-PNIPAAm with a varying amount of γ-CD. The evolution of the self assembly, dependent on the preparation process, is observable by X-ray diffraction (XRD) and DSC analyses. The γ-CD is able to be included and preferably entrapped on the PNIPAAm blocks, showing a unique loose-fit aggregate structure after the click reaction. Most γ-CDs gradually slip over to the middle PPG block of Pluronic F68, giving rise to a characteristic channel-type crystal structure in the dialysis process. In addition, the lower critical solution temperature (LCST) is sharply enhanced due to the coverage of the remaining γ-CDs hindering the thermally responsive aggregation of the PNIPAAm blocks.