A new approach to the synthesis of polyrotaxanes from the polyethylenimine‒block‒poly(ethylene glycol)‒block‒polyethylenimine copolymer and alpha-cyclodextrin has been proposed. It has been shown that the acylation of free amino groups of polypseudorotaxane effectively blocks decomposition of the complex in solution. The structure of the synthesized copolymers has been studied in detail by 1Н and 13С NMR spectroscopy, IR analysis, and GPC. It is assumed that the observed abnormally high optical activity of the resulting rotaxanes is probably associated with the formation of chiral helical supramolecular structures.

Polyrotaxanes with poly-2-alkyl-2-oxazoline blocking moieties have been successfully synthesized. The structure of the synthesized samples was confirmed by NMR spectroscopy, and the molar masses were measured by light scattering and GPC. The density of cyclodextrin rings on polyethylene glycol did not depend on the structure of poly-2-alkyl-2-oxazoline chains and ranged from 2 to 5. A high specific optical rotation of the prepared polyrotaxanes is found which is caused by the formation of hydrogen bonds between neighboring macrocycles. The behavior of water-salt solutions of synthesized polyrotaxanes depended on the size of the poly-2-alkyl-2oxazoline side groups. Only polymers with poly-2-isopropyl-2-oxazoline and poly-2-n-propyl-2-oxazoline blocking moieties were thermoresponsive in aqueous solutions, and the phase separation temperature decreased at passage from a polymer with poly-2-isopropyl-2-oxazoline to a sample with poly-2-n-propyl-2-oxazoline. Aqueous solutions of polyrotaxanes with smaller side groups were molecularly dispersed at all temperatures, and the polymer with poly-2-butyl-2-oxazoline blocking chains did not dissolve in water.