Modular Synthesis of Thermosensitive P(NIPAAm-co-HEMA)/β-CD Based Hydrogels via Click Chemistry

Two kinds of representative polymers, poly(N-isopropylacrylamide) (PNIPAAm) and beta-cyclodextrin (beta-CD) were selected and modified with azide and alkyne fucntional groups, respectively. When the solutions of these two modified polymers were mixed together, a cross-linking reaction, a type of Huisgen's 1,3-dipolar azide-alkyne cycloaddition, occurred in the presence of Cu(I) catalyst. The strategy described here provides several advantages for the hydrogel formation including mild reaction conditions and controllable gelation rate. The resulted hydrogels were studied in terms of scanning electric microscopy (SEM), equilibrium swelling ratio and swelling/shrinking kinetics. The data obtained demonstrated the hydrogels had a porous structure as well as favorable thermosensitivity.