AN NMR INVESTIGATION OF THE FORMATION OF THE CRYSTALLINE COMPLEX (PEO)(3)NACLO4

Cryoground and mixed powders of the constituents of the material PEO3N aClO4 have been monitored by nuclear magenetic resonance spectroscopy (NMR), and by X-ray techniques, at room temperature and above, to expl ore the formation of the crystalline complex. The proton, C-13, and Na -23 nuclei are observed. Similar 38:1 and 10:1 initially unreacted pow ders are also monitored to help in this assignment. The C-13 data on t he amorphous fraction shows a monotonic shift with sodium concentratio n in the amorphous/liquid state at 360 K, giving rise to the possibili ty of using C-13 shifts as a measure of cation concentration in the am orphous state. The Na-23 and X-ray results indicate that the crystal s tarts to form at room temperature. At the maximum temperature of the s pinning NMR probe (similar to 360 K) the crystal formation is rapid bu t a residual amount (similar to 5%) of NaClO4 remains undissolved. Int erestingly, the initial growth of the 'sodium in polymer' NMR spectral intensity follows a similar pattern in all three samples monitored, 3 :1, 10:1, and 38:1, indicating that the 3:1 complex is a preferred for m for sodium perchlorate in polyethylene oxide (PEO).