Preparation and characterization of supramolecular structured hydrogels using F127 through atom transfer radical polymerization

Thermosensitive supramolecular hydrogels with tunable crosslinking networks using polypseudo-rotaxanes (PPRs) as macroinitiator, polyethylene glycol diacrylate (PEGDA) as crosslinker and 2-hydroxyethyl methacrylate (HEMA) were prepared by atom transfer radical polymerization (ATRP) in water. PPRs were prepared by supramolecular self-assembly of α-cyclodextrin or 2-bromoisobutyryl bromide modified α-cyclodextrin (α-CD-BIBB) and F127 with bromopropionyl bromide terminated. The products and PPRs were characterized by FT-IR and ¹H-NMR. Wide angle X-ray diffraction demonstrates that PPRs have crystal structure. The swelling ratio (SR) decreases with introduction of α-CD, increases with introduction of α-CD-BIBBs. With increase of HEMA concentration, SR decreases, but with increase of PEGDA concentration, SR increases. Between 20°C and 50°C, the introduction of PHEMA chains decreases the temperature responsiveness of networks, but the hydrogels prepared with α-CD-BIBBs threading onto the F127 chains show the best thermo-sensitivity and well chemical strength. The thermosensitive mechanism of hydrogels is related to the aggregation of poly(propylene oxide)(PPO) blocks in copolymer.