Polyelectrolyte hydrogels based on n-alkyl methacrylate esters(n-AMA)

acrylic acid and acrylamide cross-linked with 4

4′-di(methacryloylmino)azobenzene were prepared．The deswelling of gels was observed under non-contact electric fields

while the gels with the longer hydrophobic side-chains proceeded as welling before deswelling．The gels first bend toward the cathode under non-contact electric fields

and the direction or degree of bending waves with the passage of time or when higher voltages are applied. The gels can turn back to the swollen shape when the electric field is removed．These properties of the gels are related to electro-osmosis

electrodiffusion

electrolysis

and hydrophobic interactions．