The cyclooctamethyltetrasiloxane (D4) plasma composited membranes were prepared by D4 plasma polymer deposited on the porous polypropylene substrate under the conditions of frequency 13.56 MH power 50-100 W

pressure 0.05-0.2 mbar

low-electrode temperature 20±2℃

deposite time 7-60 min. The oxygen permeation rate Jo2 andd oxygen-nitrogen separation coeff. αo/N of the obtained membranes are 0.5-2×10-5 cm3(STP)/cm2·sec·cmHg and 3.3-3.8

respectively. The formation process of the composited membranes was studied by means of SEM together with the gas peameation properties of the membranes obtained at different reaction time.