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.

Highlighted in Nature News & Views by Prof. A. L. Skov