A series of electric field sensitive gels were prepared by free-radical polymerization with acrylic acid(AA) and methyl acrylate (MA) as monomers

N

N′-methylene bisacrylamide as crosslinking agent

ammounium persulfate and tetramethylethylenediamine as initiator and accelerator

respectively.The structures and properties of the gels were changed with monomer ratio of AA and MA.The influences of the concentration of aqueous NaCl solutions and pH buffer solutions on the equilibrium swelling ratios of the gels were studied in detail.It is shown that the concentration of NaCl and the pH of the buffer solution affect the swelling properties of the P(AA-co-MA) gels greatly.Moreover

the contraction of the gels induced by a direct current electric field was investigated.The gels exhibited excellent electric sensitivity.Among the gels obtained in this investigation

the gel with a monomer ratio

VAA/(VAA+VMA) of 0.667 showed the best electrical contraction properties.According to the results of the experiment

the mechanism of the electric field induced contraction was discussed.