Tough Stimuli-Responsive Supramolecular Hydrogels with Hydrogen-Bonding Network Junctions
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- 作者：Mingyu Guo ; Louis M. Pitet ; Hans M. Wyss ; Matthijn Vos ; Patricia Y. W. Dankers ; E. W. Meijer
- 刊名：Journal of the American Chemical Society
- 出版年：2014
- 出版时间：May 14, 2014
- 年：2014
- 卷：136
- 期：19
- 页码：6969-6977
- 全文大小：553K
- 年卷期：v.136,no.19(May 14, 2014)
- ISSN：1520-5126
文摘
Hydrogels were prepared with physical cross-links comprising 2-ureido-4[1H]-pyrimidinone (UPy) hydrogen-bonding units within the backbone of segmented amphiphilic macromolecules having hydrophilic poly(ethylene glycol) (PEG). The bulk materials adopt nanoscopic physical cross-links composed of UPy鈥揢Py dimers embedded in segregated hydrophobic domains dispersed within the PEG matrix as comfirmed by cryo-electron microscopy. The amphiphilic network was swollen with high weight fractions of water (wH2O 鈮?0.8) owing to the high PEG weight fraction within the pristine polymers (wPEG 鈮?0.9). Two different PEG chain lengths were investigated and illustrate the corresponding consequences of cross-link density on mechanical properties. The resulting hydrogels exhibited high strength and resilience upon deformation, consistent with a microphase separated network, in which the UPy鈥揢Py interactions were adequately shielded within hydrophobic nanoscale pockets that maintain the network despite extensive water content. The cumulative result is a series of tough hydrogels with tunable mechanical properties and tractable synthetic preparation and processing. Furthermore, the melting transition of PEG in the dry polymer was shown to be an effective stimulus for shape memory behavior.