With the world’s focus on reducing our dependency on fossil-fuel energy, the scientific community can investigate new plastic materials that are much less dependent on petroleum than are conventional plastics. Given increasing environmental issues, the idea of replacing plastics with water-based gels, so-called hydrogels, seems reasonable. Here we report that water and clay (2–3 per cent by mass), when mixed with a very small proportion (<0.4 per cent by mass) of organic components, quickly form a transparent hydrogel. This material can be moulded into shape-persistent, free-standing objects owing to its exceptionally great mechanical strength, and rapidly and completely self-heals when damaged. Furthermore, it preserves biologically active proteins for catalysis. So far1 no other hydrogels, including conventional ones formed by mixing polymeric cations and anions2,3 or polysaccharides and borax4, have been reported to possess all these features. Notably, this material is formed only by non-covalent forces resulting from the specific design of a telechelic dendritic macromolecule with multiple adhesive termini for binding to clay.
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Q.W. thanks the Japan Society for the Promotion of Science postdoctoral fellowship for foreign researchers. We thank Y. Arakawa for his support for the synthesis of PEG-G3-dendron.
Author Contributions Q.W. synthesized Gn-binders and analysed the properties of hydrogels; K.O. and K.K. noticed adhesion of guanidinium-ion-appended dendrimers to glass surfaces; M.Y. assisted the rheological studies; E.L. and M.L. performed cryogenic transmission electron microscopy; and T.A., J.L.M. and Q.W. designed the study, analysed the data and wrote the paper.
The authors declare no competing financial interests.
This file contains Supplementary Methods, Supplementary Synthesis of Compounds 7, 9 and 11, Binders G1, G2 and G3 and PEG-G3-dendron (25), a Supplementary Reference, Oxidation of o-Phenylenediamine with H202 Catayzed Myoglobin (Mb) and Supplementary Figures S1- S8 with Legends. (PDF 13251 kb)
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Wang, Q., Mynar, J., Yoshida, M. et al. High-water-content mouldable hydrogels by mixing clay and a dendritic molecular binder. Nature 463, 339–343 (2010) doi:10.1038/nature08693
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