The hydrogels capable to interpolymer complex formation have been synthesized by direct radical copolymerization of methacrylic acid with poly(ethylene oxide) bis-macromonomer bearing methacrylate terminal groups. The swelling behavior of these hydrogels in electric field has been studied. The hydrogels were shown to undergo contraction or additional swelling depending on solution pH. In weakly acidic region (pH 5.1) the contraction of the network was observed. In these conditions the swelling behavior of the hydrogel is affected by the complex formation between unionized carboxylic groups and oxyethylene units within the networks and the gel sample has relatively low swelling degree and network charge. In basic region (pH 9.18) the polycomplex is destroyed and the network has higher charge density and higher swelling degree. Under the action of electric field such hydrogel swells additionally. An increase in ionic strength of solution decreases the amplitude of hydrogels contraction
