We proposed a novel method for designing CO₂ permselective organosilica/polymer membranes with a dual-network structure composed of silica (first) and alkylamine-based (second) networks to control molecular sieving and CO₂ adsorption properties in the membrane. Organosilica/polymer membranes were fabricated using 1,2-bis(triethoxysilyl)ethane (BTESE) or 1,2-bis(triethoxyailyl)acetylene (BTESA) as the first network, with polyethylenimine (PEI) as the second network via the sol–gel process. CO₂ adsorption measurements of BTESE/PEI films were conducted via in situ Fourier transform infrared to evaluate the effects that different types of acid catalysts exert on CO₂ adsorption properties. The results showed that only BTESE/PEI films prepared with a catalyst of acetic acid (HAc) display impressive chemical reactions between CO₂ and amine groups, whereas the use of HCl may deactivate the amine groups. We found that the gas permeation properties of organosilica/PEI membranes were greatly dependent on the Si-precursor. Almost no selectivity could be confirmed for BTESA/PEI membranes, although pure BTESA membranes did show molecular sieving properties. However, BTESE/PEI membranes showed improved separation performance compared with that of pure BTESE membranes due to a reduction in the free volume (BTESE: H₂/CH₄ selectivity < 100, BTESE/PEI: H₂/CH₄ > 100). Moreover, the pore size of BTESE/PEI membranes could be controlled via the BTESE/PEI ratio. In conclusion, we successfully designed a dual-network structure with a controlled pore size via changes made to the Si-precursor and/or to the Si-precursor/PEI mixing ratio.

中文翻译：

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双网络结构二氧化硅衍生膜的孔结构可控性和CO ₂渗透性能

我们提出了一种设计 CO ₂选择性渗透有机二氧化硅/聚合物膜的新方法，该膜具有由二氧化硅（第一）和烷基胺基（第二）网络组成的双网络结构，以控制膜中的分子筛分和 CO ₂吸附特性。使用 1,2-双（三乙氧基甲硅烷基）乙烷（BTESE）或 1,2-双（三乙氧基甲硅烷基）乙炔（BTESA）作为第一个网络，聚乙烯亚胺（PEI）作为第二个网络，通过溶胶 -凝胶过程。BTESE/PEI 薄膜的CO ₂吸附测量是通过原位傅立叶变换红外进行的，以评估不同类型的酸催化剂对 CO _{2 的影响}吸附特性。结果表明，只有用乙酸 (HAc) 催化剂制备的 BTESE/PEI 薄膜显示出令人印象深刻的 CO ₂和胺基团之间的化学反应，而使用 HCl 可能会使胺基团失活。我们发现有机二氧化硅/PEI 膜的气体渗透特性在很大程度上取决于 Si 前体。BTESA/PEI 膜几乎没有选择性，尽管纯 BTESA 膜确实显示了分子筛分特性。然而，由于自由体积的减少，BTESE/PEI 膜与纯 BTESE 膜相比表现出更高的分离性能（BTESE：H ₂ /CH ₄选择性 < 100，BTESE/PEI：H ₂ /CH ₄> 100）。此外，BTESE/PEI 膜的孔径可以通过 BTESE/PEI 比率控制。总之，我们通过改变硅前体和/或硅前体/PEI 混合比，成功设计了具有可控孔径的双网络结构。