ESR OF SPIN-LABELED CROSS-LINKED PERFLUORO POLYETHERS AND PROPERTIES OF ADSORBED WATER

Cross-linked perfluoro polyethers showed properties such as glass transition temperatures and thermal stability, as determined by DSC and TGA, which are typical of usual perfluorinated polymers. These products were studied by ESR in the form of their spin-labeled adducts and after swelling with water solutions containing small nitroxide radicals. The analysis of the ESR line shapes revealed a relatively high flexibility of the perfluoro ether backbone. Formation of water pools in the polymer network was suggested on the basis of the ESR results, and the rheological properties of the swelling water were similar to those of water adsorbed in other perfluorinated ionomers.