P-31 SOLID-STATE NMR-STUDIES OF THE STRUCTURE OF AMINE-INTERCALATED ALPHA-ZIRCONIUM PHOSPHATE .2. TITRATION OF ALPHA-ZIRCONIUM PHOSPHATE WITH NORMAL-PROPYLAMINE AND NORMAL-BUTYLAMINE

The intercalation of alpha-zirconium phosphate, alpha-Zr(HPO4)2.H2O, with n-propyl- and n-butylamines has been examined using solid-state P-31 NMR. Intercalation proceeds in a stepwise fashion according to the "moving boundary model". A number of intermediate intercalation compounds are formed having the formulas Zr(HPO4)2-x(CH3(CH2)nNH3PO4)x.yH2O (0 < x < 2, n = 2, 3). These contain a variable number of phases, having different lattice spacings. With increasing amine content a saturated phase (x = 2) is eventually obtained. The amine is protonated on intercalation. At low amine contents, the amine replaces the lattice water and lies parallel to the phosphate layers. With increased amine loading, the alkyl chain adopts more upright orientations and finally makes an angle of almost-equal-to 55-degrees to the phosphate layers when x = 2. The addition of water to the intercalate at low amine loadings increases the rate of exchange occurring in the interlayer region and suggests that the various phases occur in equilibrium within the same layer of a single crystal.