DEFORMATION OF IONIC POLYMER GELS BY ELECTRIC-FIELDS

When an electric field is applied to an ionic gel in a buffer solution, the anode side of the gel shrinks if the gel is contacting with the electrode, while it swells if the gel is placed with sufficient separation from the electrode. We calculate the changes of ion concentration profiles under an electric field, taking account of ion transports and electrochemical reactions. Combining these results with Flory's theory for the swelling of ionic gels, we explain the above phenomena. We predict that the swelling behavior is governed by the concentration of the dominant ions and that the swelling speed is proportional to the square of the electric current.