Synthesis and characterization of thermosensitive and supramolecular structured hydrogels

New kinds of thermosensitive and supramolecular structured hydrogels were synthesized via copolymerization of N-isopropylacrylamide (NIPA) with photocurable and biodegradable polypseudorotaxanes as cross-linkers under UV irradiation. The polypseudorotaxanes were prepared by supramolecular self-assemblies of α-cyclodextrins threaded onto amphiphilic LA-PEG-LA copolymers end-capped with methacryloyl groups. The structure of the hydrogels was characterized in detail with FTIR, ¹H NMR, XRD, DSC, and TGA techniques. The analytical results have demonstrated that the channel-type crystalline structure of inclusion complexes (ICs) remains in as-obtained hydrogels. Their swelling behavior was measured gravimetrically in the temperature range from 22 to 67 °C. It was observed that the crosslinked hydrogel made of only the macromer guest shows also thermosensitive. However, this stimuli-responsive property disappears when α-CDs are threaded onto the polymeric backbone and reappears when PNIPA blocks are introduced. The theromsensitivity of these hydrogels could be modulated by changing the PNIPA content as well as the α-CD to macromer ratio.