Preparation of Carbon Dioxide Separation Membrane by Plasma Polymerization

采用等离子体聚合法制得二甲基二甲氧基硅烷（DMDMOS）、十甲基环五硅氧烷（DMCPS）和1,1,3,3-四甲基二硅氧烷（TMDSO） 3种硅化合物，并测定了其对二氧化碳和氮气的溶解度系数和渗透系数。讨论了沉积膜的渗透性能。由DMDMOS、DMCPS和TMDSO形成的等离子体聚合物对二氧化碳具有优先溶解度。二氧化碳的溶解度系数与等离子体聚合物中Si-(O-)_4基团的浓度密切相关。然而，这些等离子体聚合物对二氧化碳没有选择性渗透。扩散过程而不是溶液过程控制二氧化碳在等离子体聚合物上的渗透。硅化合物形成的等离子体聚合物，如果其交联较少，有望成为制备co_2选择性膜的良好材料。

Three silicon compounds, dimethyldimethoxysilane (DMDMOS), decamethylcyclo-pentasiloxane (DMCPS), and 1,1,3,3-tetramethyldisiloxane (TMDSO), were plasma-poly-merized, and the solubility coefficient and the permeation coefficient of carbon dioxide and nitrogen gas were determined. The permeation properties of the deposited films were discussed. The plasma polymers formed from DMDMOS, DMCPS, and TMDSO showed pre-ferential solubility for carbon dioxide. The solubility coefficient of carbon dioxide was closely related to the concentration of Si-(O-)_4 moieties in the plasma polymers. However, these plasma polymers showed no selective permeation of carbon dioxide. The diffusion process rather than the solution process controlled the permeation of carbon dioxide across the plasma polymers. Plasma polymers formed from silicon compounds, if the polymers have less cross-linkage, are expected to be a good material for CO_2-selective membrane.