| Summary: | 碩士 === 國立勤益科技大學 === 化工與材料工程系 === 98 === In this study, composite membranes with the function of gas barrier were developed. A silicon nitride (Si3N4) thin film, as a gas barrier layer, was deposited on polyimide (PI) or polyimide/aluminium oxide (PI/Al2O3) hybrid substrates by RF magnetron sputtering. The parameters of sputtering process were optimized and the characteristics of the resultant composite membranes were studied in order to obtain a gas barrier thin film on PI/Al2O3 hybrid substrates.
First, Si3N4 was deposited on PI substrates synthesized from 4,4'-oxydianiline (ODA) and 3,3'-oxydiphalic anhydride (ODPA) via polycondensation reaction. Different working pressures (4~8m Torr) and sputtering powers (40~100W) were performed to obtain various thicknesses or structures of Si3N4 thin films on PI substrates. XPS results confirmed the chemical composition of all deposited film on PI substrate was Si3N4. With a lower working pressure (4m Torr) and higher sputtering power (100W), the deposited Si3N4 thin film exhibits denser structure (by FE-SEM), lower RMS surface roughness (by AFM) and lower transmission rate of water vapor (WVTR, 0.88 g-mil/m2-day). A critical Si3N4 thickness of 100 nm was observed to obtain a WVTR as low as 5.4 g-mil/m2-day, when the sputtering power and working pressure were controlled at 100W and 6m Torr, respectively. The thickness of Si3N4 has no effect on the optical transmittance at 550 nm, Td5 and Tg. They were over 86 %, around 538 oC and 268 oC, respectively, for all synthesized composited membranes under various sputtering procedures.
In addition, a Si3N4 thin film with a thickness of 100 nm was deposited on various PI/Al2O3 hybrid substrates under a controlled sputtering condition, 4m Torr and 100W. These hybrid substrates with different Al2O3 contents were prepared via sol-gel procedure and showed higher thermal stability, better dimensional stability and stronger mechanical property than pure PI substrate. The bending tests suggested the composite membrane with a hybrid substrate of PI/Al2O3 with 10 wt. % Al2O3 has better hinder-resistant for crack. XPS’s composition-depth profiles analysis confirm the existence of Al-N and Al-O-Si bonding at the interface of Si3N4 thin film and PI/Al2O3 hybrid substrate.
|
|---|
