Synthesis of novel engineering polymers containing basic side groups and their application in acid-base polymer blend membranes

New modified PSU Udel(R) containing N-basic side groups like pyridine and dimethylamino groups have been developed. The modified PSU was synthesized via (i) lithiation of PSU ortho to the sulfone bridge and (ii) reaction of the lithiated PSU with aromatic ketones like 2,2'-bipyridylketone, 4,4'-dimethylaminobenzophenone, aromatic aldehydes like 2-, 3-, and 4-pyridinealdehyde, and 4-N,N-diethylaminobenzaldehyde, and aromatic carboxylic acid esters like isonicotinic acid ethyl ester and 4-N,N-dimethylaminobenzoic acid ethyl ester. The basic PSU polymers were characterized via NMR, elemental analysis, and thermogravimetry (TGA). Selected basic polymers were mixed with poly(etheretherketone) (PEEK) sulfonic acid to yield polymeric acid-base blends. The obtained blend membranes were characterized in terms of ionic conductivity by impedance spectroscopy, in terms of morphology by transmission electron microscopy (TEM), and in terms of thermal stability by TGA. The acid-base blends show good ionic conductivities at ion-exchange capacities of greater than or equal to 1 meq/g, and good thermal stabilities. The TEM investigations yielded the result that the acid-base-blends are miscible-no polymer-microphase separation could be observed. (C) 2001 Elsevier Science B.V. All rights reserved.