138321-99-0Relevant articles and documents
Synthesis and characterization of sulfonated polyimides containing trifluoromethyl groups as proton exchange membranes
Zhang, Qingshuang,Li, Qiaoling
, p. 1460 - 1466 (2011)
A novel sulfonated diamine, 4,4′-bis(4-amino-3- trifluoromethylphenoxy) biphenyl 3,3′-disulfonic acid (F-BAPBDS), was successfully synthesized by nucleophilic aromatic substitution of 4,4′-dihydroxybiphenyl with 2-chloro-5-nitrobenzotrifluoride, followed by reduction and sulfonation. A series of sulfonated polyimides of high molecular weight (SPI-x, x represents the molar percentage of the sulfonated monomer) were prepared by copolymerization of 1,4,5,8-naphathlenetetracarboxylic dianhydride (NTDA) with F-BAPBDS and nonsulfonated diamine. Flexible and tough membranes of high mechanical strength were obtained by solution casting and the electrolyte properties of the polymers were intensively investigated. The copolymer membranes exhibited excellent oxidative stability due to the introducing of the CF3 groups. The SPI membranes displayed desirable proton conductivity (0.52 × 10-1-0.97 × 10-1 S·cm -1) and low methanol permeability (less than 2.8 × 10 -7 cm2·s-1). The highest proton conductivity (1.89 × 10-1 S·cm-1) was obtained for the SPI-90 membrane at 80°C, with an IEC of 2.12 mequiv/g. This value is higher than that of Nafion 117 (1.7 × 10-1 S·cm-1). Furthermore, the hydrolytic stability of the obtained SPIs is better than the BDSA and ODADS based SPIs due to the hydrophobic CF3 groups which protect the imide ring from being attacked by water molecules, in spite of its strong electron-withdrawing behaviors. Copyright
