A Morphological Study of Poly [ bis ( trifluoroethoxy ) phosphazene ] Using High Resolution Solid - State 1 H , 19 F , 31 P and 13 C NMR Spectroscopy

High-resolution F, H, P and C solid-state NMR methods were assessed to ascertain their suitability for studying the morphological behavior in the crystalline domain of phosphazene polymers with partially fluorinated side-chains. Poly[bis(trifluoroethoxy)phosphazene] (PBFP) was used as a sample system. Fast magic angle spinning (MAS), along with simultaneous F and H decoupling using the xy-16 sequence, were employed, as this has proven to greatly improve resolution in C spectra of perfluorinated materials. Information obtained from Discrimination Induced by Variable Amplitude Minipulses (DIVAM) nutation experiments and cross-polarization (CP) methods aided the deconvolution analysis used to identify all components in the H, F and C signals. DIVAM nutation experiments were also used to discriminate between signals from the amorphous and crystalline domain. The crystallinity in the solvent-cast PBFP was determined to be approximately 70%, which was seen to increase to approximately 80% in the heat-treated material, for all nuclei studied. A preliminary assignment was made for the crystalline signals in the H and C spectra to the a-, band c-phases. Therefore, high-resolution C and H methods are valuable tools for morphological investigations into this class of polymer.