TABLE OF CONTENTS Infrared spectra are very useful for many purposes; for instance, equivalent weight (EW) determination, following chemical reactions of the functional groups, checking completeness of hydrolysis, etc.
The following bands have been observed for perfluorinated ionomers:
-(CF 2) n - (the polymer backbone): A weak band at 2360/cm, which is useful as a thickness band with which other bands are compared and a broad strong band from 1100 to 1300/cm.
-SO 2F (the precursor): A weak band at 2710/cm useful for EW determinations and a very strong one at 1470/cm with a side peak at 1450/cm. This peak is useful for checking completeness of hydrolysis.
-SO 2Cl: A strong band at 1420/cm.
-SO 3 - (the ionic form): A medium band at 1055/cm.
-SO 2 - (the sulfinate salt): Bands at 940 and 1010/cm.
-CO 2CH 3 (the precursor): A strong band at 1780/cm. The free carboxylic acid has a similar absorption.
-CO 2 - (the ionic form): A strong band at 1690/cm. The shift from 1780 to 1690/cm on neutralization, and back on acidification can be used to confirm a suspected carboxylic function.
-COOH: Carboxylate in precursor, acid or salt form, if it has more than one -CF 2 - group between the carboxylic function and the next ether linkage: a peak at 1020/cm. The absence of this peak can be used to recognize carboxylate polymers made by chemical conversion of the typical sulfonic precursor.
-O- (the...
