Aggregation Structure and Gas Separation Properties of Double-layer membranes Plasma-polymerized from Silicone Compounds and Perfluorobenzene

It was known that the control of electron temperature within plasma polymerization system was important in order to obtain reproducibility of membrane structure by plasma polymerization.The double probe method was used to measure the electron temperature.Electron temperature was delicately affected by both power and pressure of the discharge system。Besides，it exerted seriously a influence upon polymerization reaction。A plot of the electron temperature against the power of discharge showed a minimum point.In the cases of polymerization of HMDS and HFB at the pressure of 0.02 torr，the minimum point was observed at discharge power of 20W and 40W，respectively。All the operation of plasma polymerization were carried out at these minimum points.Gas permeability of obtained membrane was measured and structure of membrane was analyzed using scanning electron microscope，infrared spectometry and X-ray photoelectron spectroscopy.As the results，it was found that the temperature of me…More mbrane under plasma polymerization had a great influence on the structure of membrane and gas permeation properties.Membrane polymerized from HMDS at 20°C，which contained a high rate of siloxane bond and a low rate of alkyl groups，was rather inorganic and easy to crack。But that polymerized at-5óC contained a high rate of alkyl groups and was an organic substrate similar to the silicon rubber.The gas permeation rate of this membrane，which was2000-3000A^^óin thickness，was the order of 10^&lt；-4&gt；cc(STP)/cm^2·s·cmHg.Separation ratio of oxygen to nitrogen was almost constant at 2.0 in the wide range of the thickness0 of membrane.Then，doxgble-layer membranes which put HFB layer of 500-1000A^^óon HMDS layer of 2500A^^°Were made.The permeation rate of oxygen through this membrane was7x10^&lt；-5&gt；cc(STP)/cm^2·s·cmHg and the separation ratio(R_&lt；O2&gt；/F_&lt；N2&gt；)was more than 2.5。These results suggest that，the double-layer membrane in present study have high potential to be the practical membrane for oxygen enrichment。Less：Less

It was known that the control of electron temperature within plasma polymerization system was important in order to obtain reproducibility of membrane structure by plasma polymerization. The double probe method was used to measure the electron temperature. Electron temperature was delicately affected by both power and pressure of the discharge system. Besides, it exerted seriously a influence upon polymerization reaction. A plot of the electron temperature against the power of discharge showed a minimum point. In the cases of polymerization of HMDS and HFB at the pressure of 0.02 torr, the minimum point was observed at discharge power of 20 W and 40 W, respectively. All the operation of plasma polymerization were carried out at these minimum points. Gas permeability of obtained membrane was measured and structure of membrane was analyzed using scanning electron microscope, infrared spectometry and X-ray photoelectron spectroscopy. As the results, it was found that the temperature of me … More mbrane under plasma polymerization had a great influence on the structure of membrane and gas permeation properties. Membrane polymerized from HMDS at 20 ﾟC , which contained a high rate of siloxane bond and a low rate of alkyl groups, was rather inorganic and easy to crack. But that polymerized at - 5 ﾟC contained a high rate of alkyl groups and was an organic substrate similar to the silicon rubber. The gas permeation rate of this membrane, which was 2000-3000 A^^ﾟ in thickness, was the order of 10^<-4> cc(STP)/cm^2・s・cmHg. Separation ratio of oxygen to nitrogen was almost constant at 2.0 in the wide range of the thickness 0of membrane. Then, doxgble-layer membranes which put HFB layer of 500-1000 A^^ﾟ on HMDS layer of 2500 A^^ﾟ Were made. The permeation rate of oxygen through this membrane was 7 x 10^<-5> cc(STP)/cm^2・s・cmHg and the separation ratio(R_<O2>/F_<N2>) was more than 2.5. These results suggest that, the double-layer membrane in present study have high potential to be the practical membrane for oxygen enrichment. Less