Suprarmolecular hydrogels based on low‐molecular‐weight poly(ethylene glycol) and α‐cyclodextrin

Abstract

Abstract In previous studies, crystalline precipitates, not stable hydrogels, were obtained when low‐molecular‐weight (MW) poly(ethylene glycol) (PEG; weight‐average MW = 400–5000) was used to interact with α‐cyclodextrin (α‐CD). In this study, the gelation ability of low‐MW PEG (number‐average MW = 2000, PEG‐2000) and α‐CD was systematically investigated through the variation in the concentration of PEG‐2000 in water ( C PEG‐2000 ) and the feeding molar ratio of the PEG repeat unit to α‐CD ( R ). The results show that a stable supramolecular hydrogel could be constructed when C PEG‐2000 was kept at 40 mg/mL and R was 6.3. The inclusion complexation between α‐CD and PEG‐2000 and the effect of C PEG‐2000 and R on the stability of the hydrogels were characterized by differential scanning calorimetry, X‐ray diffraction, scanning electron microscopy, and rheology measurements. The resulting PEG‐2000‐based hydrogels retained the basic characteristics of supramolecular physical hydrogels, especially the property of shear thinning. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013