Three Semi-interpenetrating polymer networks (Semi-IPNs) composed of poly(2-dimethylaminoethyl methacrylate) (PDMAEMA)

and poly (ethylene oxide)

PEO

were synthesized by γ-radiation technology. The optimum synthesizing conditions have been found in the work．The equilibrium swelling ratio

EDS

of the Semi-IPNs was effected by the weight ratio between PEO and DMAEMA. When there was a little PEO (～3 wt％) in the Semi-IPNs

the EDS of Semi-IPNs was much larger than that of PDMAEMA

as the weight ratio of PEO in Semi-IPNs increased the EDS of Semi-IPNs decreased gradually and tended to be stable．The Semi-IPNs showed obvious electric-responsiveness

and the effect was dependent on the weight ratio of PEO in the Semi-IPNs．The electric-responsiveness was the most remarkable when the weight ratio of PEO was 5％ in Semi-IPNs. The Semi-IPNs were used successfully in entraping and electric field controled release of a Chinese traditional medicine

saponins．