A study of the T(1) transition of Poly(Bis(trifluoroethoxy)Phosphazene) (PBFP) using solid-state nuclear magnetic resonance spectroscopy

In situ solid state variable temperature NMR measurements have been made on Poly(bis(trifluoroethoxy)phosphazene above and below the first order thermotropic transition, T(1). A single mobile ordered 2D phase exists above T(1). Below T(1) and at room temperature there is a 3D phase in agreement with other physical property measurements. The OCH2CF3 side chains exhibit similar mobility on either side of the 2D in equilibrium with 3D transition. The activation energies associated with the CH2 and CF3 side groups are E sub CH2 about 17.3 kJ/mole and E sub CF3 about 13.7 kJ/mole. The spin lattice relaxation measurements for these same groups are 1.75s. and 3.55s. respectively. The crystallinity ascertained from solid state NMR results is strongly dependent upon annealing conditions and temperature of measurement.