Study on polyimide/TiO2 nanocomposite membranes for gas separation

In this paper, nanocomposite materials based on TiO2 and polyimide derived from HQDPA and DMMDA were prepared by blending of TiO2 sol and polyimide solution. Because of the improvement of the TiO2 sol preparation process and blending methods, the TiO2 content of the obtained TiO2/polyimide composite materials can reach about 40wt%. The structures and properties of the obtained TiO2/polyimide composite materials were characterized in this study. The results showed that the obtained PI/TiO2 composite membranes with TiO2 content up to 30%wt were nanocomposite membranes. There existed strong interaction between TiO2 phase and PI phase of PI/TiO2 composite membranes. The high TiO2 content in TiO2/polyimide nanocomposite membranes resulted in the great enhancement of gas separation performance of the TiO2/polyimide nanocomposite materials compared with polyimide. The H2 and O2 permeability of TiO2/polyimide nanocomposite membrane with TiO2 content of 25wt% was 14.1 and 0.718 barrer, respectively, which was 3.7 times and 4.3 times higher than that of pure polyimide (PH2 = 3.809 barrer, PO2 = 0.166 barrer). The "H2/N2 and "O2/N2 of TiO2/polyimide nanocomposite material containing 25wt% TiO2 is 187.5 and 9.5, respectively, which is higher than that of pure polyimide ("H2/N2 = 166.9, "O2/N2 = 9.3).

This work concerns the study of PI/TiO2 nanocomposite membranes with high TiO2 content for gas separation. The PI/TiO2 composite membranes with a TiO2 content up to 40wt% could be prepared by the blending of PI solution and TiO2 sol that was synthesized by the hydrolysis of TBT in NMP. The obtained PI/TiO2 composite membranes with TiO2 content up to 30wt% were nanocomposite membranes and there was strong interaction between two components in PI/TiO2 composite membranes. The results of the permeation investigation of PI/TiO2 composite membranes were very encouraging. When the TiO2 content in PI/TiO2 composite membranes was above 20wt%, the permeability of the PI/TiO2 composite membranes was remarkably enhanced and the selectivity of PI/TiO2 composite membranes remained at a high level. For the PI/TiO2 nanocomposite membranes with TiO2 content of 25wt%, the H2 and O2 permeability was 14.1 and 0.718 barrer, respectively, which was 3.7 times and 4.3 times higher than that of pure polyimide (PH2 = 3.809 barrer, PO2 = 0.166 barrer). The "H2/N2 and "O2/N2 was 187.5 and 9.5, respectively, which is higher than that of pure polyimide ("H2/N2 = 166.9, "O2/N2 = 9.3). Therefore, preparation of nanocomposite membranes was an effectual method to enhance the permeation performance of gas separation membranes. A membrane with both high permeability and selectivity could then be obtained.