Sulfonated polyimides five-member ring

Figure 24. Synthesis of a five-membered ring sulfonated polyimide containing phosphine oxide.

This class of polymers has great thermal stability and promising short-term perfor-mance. °° The six-membered ring of naphthalenic imides is preferred over the five-membered ring of phthanic imides. The latter is susceptible to acid-catalyzed hydrolysis, which leads to chain scission and membrane embrittlement. An example of six-mem-bered ring polyimides is the block sulfonated copolyimides shown below. ... 

Sulfonated polyimides (sPI) are another type of ionomers that have been prepared [5] by copolymerization of 4,4 -diamino-biphenyl 2,2 -disulphonic acid (BDSA), 4,4 -oxydianiline (ODA), and naphtalenic or phthalic anhydrides. Polyimide structures based on six-membered rings derived from naphtalenics anhydrides, such as 1,4,5,8-naphtalene tetracarboxylic dianhydride (NTDA), shown in Fig. 6.8, are more hydrolitically stable than the five-membered rings basedoxy-diphthalic anhydrides (ODPA). 

Figure 29.13 (a) Five-member ring and (b) six-member ring sulfonated polyimides. 

Gunduz, N. and McGrath, J. E. 2001. Wholly aromatic five- and six-membered ring polyimides containing pendant sulfonic acid functional groups. Polym. Preprints... 

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