© 2015 Elsevier B.V. In this work, two novel carboxyl-containing polyimides, 2,2'-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride-4,4'-diaminodiphenylmethane/3,5-diaminobenzoic acid (6FDA-MDA/DABA, FMD) and 3,3',4,4'-benzophenone tetracarboxylic dianhydride-4,4'-diaminodiphenylmethane/3,5-diaminobenzoic acid (BTDA-MDA/DABA, BMD), are synthesized via chemical and thermal imidization methods, respectively, and employed as pervaporation membranes for ethanol dehydration. Chemical structures of the two polyimides are examined by FTIR and TGA to confirm the successful synthesis. A post thermal treatment of the polyimide membranes with the temperature range of 250 to 400. °C is applied, and its effects on the membrane morphology and separation performance are studied and characterized by FTIR, TGA, WXRD, solubility and sorption test. It is believed that the thermal treatment of the carboxyl-containing polyimide membrane at a relative low temperature only leads to the physical annealing, while it may cause the decarboxylation-induced cross-linking at a higher temperature. In addition, the operation temperature in pervaporation is also varied and shown to be an important factor to affect the final membrane performance. Performance benchmarking shows that the developed polyimide membranes both have superior pervaporation performance to most other flat-sheet dense membranes. This work is believed to shed useful insights on polyimide membranes for pervaporation applications.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: The authors thank the financial support from Huazhong University of Science and Technology China (Grant nos. 0124013041, 2014YQ012), and National Natural Science Foundation of China (Grant No. 21306058) and “Thousand Youth Talent Plan” (Grant No. 222013005). Special thanks are given to Dr. Ngoc Lieu Le in King Abdullah University of Science and Technology (KAUST), Prof. Sixue Cheng in Wuhan University (China) and Prof. Lu Shao in Harbin Institute of Technology (China) for their valuable suggestions and help. We would also like to thank the Analysis and Testing Center, Huazhong University of Science and Technology for their assistance in material characterizations.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.