Cardo polyimides/TiO₂ mixed matrix membranes: Synthesis, characterization, and gas separation property improvement

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• 作者：Haixiang Sun ; Cheng Ma ; Bingbing Yuan ; Tao Wang ; Yanyan Xu ; Qingzhong Xue ; Peng Li ; Ying Kong
• 关键词：Cardo polyimide ; Mixed matrix membrane ; TiO2 morphology ; Gas separation property
• 刊名：Separation and Purification Technology
• 出版年：10 February, 2014
• 年：2014
• 卷：122
• 期：Complete
• 页码：367-375
• 全文大小：2524 K

文摘

This paper reports the synthesis of a novel cardo type polyimide PI(BTDA-BAPF-DMMDA) based on 3,3鈥?4,4鈥?benzophenone-tetracarboxylic dianhydride (BTDA), 9,9鈥?bis (4-aminophenyl) fluorine (BAPF) and 4,4鈥?biamino-3,3鈥?dimethyldiphenyl-methane (DMMDA) using the low temperature solution copolymerization method, and cardo polyimide/TiO₂ mixed matrix membranes (MMMs) were prepared by blending of TiO₂ sol and the PI solution. The incorporation of the cardo groups was achieved through the reaction between the free -COOH of polyamide acid (PAA) and the -NH₂ of the BAPF. The chemical structure and physical properties of membrane material were characterized using FTIR, ¹H NMR, DSC and XRD. Results showed that the MMMs containing 24 wt% of TiO₂ sol were nano-composite membranes with strong interactions between inorganic TiO₂ phase and organic PI phase. Compared with PI(BTDA-DMMDA) membrane, the addition of BAPF and TiO₂ greatly improved the gas separation properties of cardo PI membranes and MMMs. The gas permeation (P_O2) and ideal separation factor (a_O2/N2) of the cardo polyimide PI/TiO₂ membrane with a BAPF: BTDA molar ratio of 0.15:1 and TiO₂ content of 24 wt% were 4.5 Barrer and 15.8 respectively, which were a respective 9.4 and 4.6 times higher than that of the PI(BTDA-DMMDA) membrane. The P_O2 and a_O2/N2 of the cardo polyimide/TiO₂ MMMs prepared in this work were beyond Robeson鈥檚 trade-off upper bound, highly promising for future gas separation application.