Supramolecular Hydrogels Made of End-functionalized Low-molecular-weight PEG and α-Cyclodextrin and their Hybridization with SiO2 Nanoparticles through Host-guest Interaction
writer：Mingyu Guo, Ming Jiang*, Stergios Pispas, Wei Yu, and Chixing Zhou
keywords：supramolecular hydrogel, host-guest interaction
source：期刊
specific source：Macromolecules 2008, 41, 9744-9749.
Issue time：2008年
As quite generally stated in the literature, low-molecular-weight (MW) poly(ethylene glycol) (PEG) (Mn less than 2K) and R-cyclodextrin (R-CD) can lead to only crystalline precipitates (not hydrogels). However, in this study we found that: (1) adamantane monoend-functionalized low-MW PEG (Ada-PEG, Mn) 1.1 or 2K) and R-CD lead to hydrogels but not to crystalline precipitates and (2) -cyclodextrin (-CD) surface-functionalized silica nanoparticles (-CD-SiO2) can be well dispersed in low-MW Ada-PEG and R-CD aqueous mixtures, resulting in hybrid hydrogels. The hydrophobic aggregation of Ada-PEG in case 1 and the further functionalization of -CD-SiO2 with PEG chains due to the inclusion complexation between -CD and the Ada group attached to PEG in case 2 were found to play a key role as a supra-crosslink that promoted the gelation of the inclusion complexes of R-CD and the low-MW Ada-PEG. The resultant native and hybrid hydrogels retained the basic characteristics of the supramolecular physical hydrogels, especially the shear-thinning property. The mechanical strength and the viscosity of the hybrid hydrogel were greatly improved in comparison with those of the corresponding native hydrogels.