Molecular Dynamics simulation of the permeation of ethanol solution in Poly(1-trimethylsilylpropyne)films

• Main Authors: Tin-Wen Wang, 王亭文
• Other Authors: Liang-Yuan Shy
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/39999032160315856160

碩士 === 國立成功大學 === 化學系 === 87 === Abstract Pervaporation（PV）is a technique to separate liquid mixtures by membrane. Unlike other conventional methods, it''s based on the difference of permeation rates of the individual compenents. It''s been shown from the experiments that good separation effect can be achieved when applied to ethanol solution. In general, the permeation rate of penetrant molecule（like ethanol, water）is determined by its solubility and diffusivity. Among them, diffusion is normally dependent on size of penetrant, and the solubility is influenced by penetrant- polymer interaction. Since the time scale of molecular dynamics（MD）simulation is close to that of molecular diffusion, the separation mechanism of the pervaporation can be studied by this method. In this paper, two important regions, bulk and interfacial, have been selected to simulate the permeation process for a 10﹪ethanol solution through cis-poly（1-trimethylsilylproryne）（PTMSP）membrane. In the bulk region, water molecule was found to jump frrquenty, and diffuse faster than ethanol, owing to its small size. On the contrary, the large size and strong affinity with polymer let ethanol ofteh trapped in the holes. However, ethanol perferentially permeates into the membrane in the interfacial region because of the strong interaction between hydrophobic functional group of PTMSP and ethanol. To sum up, sorption is favored for ethanol, but diffusion is favored to water. But PTMSP is found to be a perferentially ethanol membrane from experiment. Apparently, the permeation for this system is dominated by the sorption rather than diffusion. Besides, slight swelling is also observed when the penetrants permeate into the membrane. Ths result agrees well with experiment.