An Anisotropic Hydrogel with Electrostatic Repulsion between Cofacially Aligned Nanosheets.

Mingjie Liu, Yasuhiro Ishida, Yasuo Ebina, Takayoshi Sasaki, Takaaki Hikima, Masaki Takata, and Takuzo Aida

Nature 2015, 517, 68–72.

[DOI: 10.1038/nature14060]

  Electrostatic and magnetic repulsive forces are used in various places, such as maglev trains.  However, design of polymer materials has focused overwhelmingly on attractive interactions for their reinforcement, while little attention has been given to the utility of internal repulsive forces.  In this work, we developed a hydrogel with anisotropic mechanical properties dominated by ‘electrostatic repulsion’ between negatively charged unilamellar inorganic nanosheets anisotropically aligned within it.

  The hydrogel shows unprecedented mechanical properties, where the hydrogel easy deforms along a shear force applied parallel to the nanosheet plane but is highly resistive against a compressive force applied orthogonally.  The concept of embedding repulsive electrostatics in a composite material will open new possibilities for developing soft materials with unusual functions.

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