Authors: Qigang Wang, Justin Mynar & Takuzo Aida
This protocol describes a facile, quick and reproducible preparation of hydrogels. The protocol requires four components: water, clay nanosheets (Clay-NS), a dendritic macromolecule (Gn-binder; n = generation number) and sodium polyacrylate (ASAP). Upon mixing with ASAP in water, Clay-NS, which are heavily entangled with one another, are exfoliated and dispersed homogenously because of a possible site-specific wrapping of their positive-charged edge parts with anionic ASAP. Meanwhile, Gn-binder possesses two dendron units, which are decorated with multiple guanidinium ion pendants on their periphery. A previous paper (1) reports that a mono-dendron version of Gn-binder interacts strongly with the oxyanionic surface groups of proteins. Upon addition of Gn-binder to the aqueous solution of Clay-NS with ASAP, exfoliated nanosheets of clay are crosslinked kinetically through multivalent salt-bridge formation between the guanidinium ion pendants of Gn-binder and oxyanionic groups on the nanosheet surface. Consequently, the hydrogelation takes place.
A typical example of the hydrogelation with Clay-NS, ASAP, and Gn-binder is given below:
Approximately 13 minutes
Magnetic stirring of an aqueous suspension of Clay-NS after addition of ASAP (dispersion of Clay-NS); approximately 10 minutes, Magnetic stirring of the resulting dispersion after addition of G3-binder; approximately 1 minute, Standing of the resulting mixture (hydrogelation); approximately 2 minutes.
Gn-binder is highly adhesive to glass:
High-water-content mouldable hydrogels by mixing clay and a dendritic molecular binder, Qigang Wang, Justin L. Mynar, Masaru Yoshida, Eunji Lee, Myongsoo Lee, Kou Okuro, Kazushi Kinbara, and Takuzo Aida, Nature 463 (7279) 339 - 343 21/01/2010 doi:10.1038/nature08693
Qigang Wang, The University of Tokyo
Justin Mynar & Takuzo Aida, JST ERATO-SORST and The University of Tokyo
Source: Protocol Exchange (2010) doi:10.1038/nprot.2010.23. Originally published online 22 January 2010.