HMDSO/MCE 電漿披覆膜沉積層結構與氣體分離效能之研究

Abstract

In this study, SiOxCyHz/Mixed cellulose esters (MCE) plasma deposited membranes were fabricated by hexamethyldisiloxane (HMDSO) plasma enhanced chemical vapor deposition (PECVD) on the MCE, which has some advantages, e.g., monomer doesn’t have double bond and deposition layer with good physical and chemical resistances. The effects of plasma power and deposition time on the deposition layer pore size and pore numbers of the SiOxCyHz/MCE plasma deposited membranes were studied. It shows that the substrate temperature increases with increasing the deposition time. Meanwhile, the enhancement of ion bombardment and etching effect results the deposition rate decreases during the plasma deposition process. The XPS data revealed that the composition of SiO4 of the deposition layer increased with increasing the plasma power and deposition time. The positron annihilation spectroscopy (PAS) coupled with a variable monoenergy slow positron beam was utilized to detect the depth profile of the pore size and multilayer structure of the plasma deposited membrane. It was found that the deposition layer (mixtures of HMDSO species and MCE species) had more hydrocarbon group, resulting in the deposition layer had a looser structure at the initial period of plasma deposition. However, the MCE species content of the deposition layer decreases as the deposition time further increases. The deposition layer becomes denser. From the PALS, the o-Ps lifetime (τ3 correspond to the pore size) decreases along the plasma deposition layer growth direction. These results correspond with the XPS very well. The plasma deposited membrane was applied for O2/N2 separation. The O2 permeance decreased and the O2 concentration in the permeate enhanced when the plasma power and deposition time increased.